Sample code for listing objects in OSS - Object Storage Service

This topic describes how to list all objects, a specific number of objects, and objects whose names contain a specific prefix in an Object Storage Service (OSS) bucket.

Usage notes

In this topic, the public endpoint of the China (Hangzhou) region is used. If you want to access OSS from other Alibaba Cloud services in the same region as OSS, use an internal endpoint. For more information about OSS regions and endpoints, see Regions, endpoints and open ports.
In this topic, access credentials are obtained from environment variables. For more information about how to configure access credentials, see Configure access credentials.
In this topic, an OSSClient instance is created by using an OSS endpoint. If you want to create an OSSClient instance by using custom domain names or Security Token Service (STS), see Create an OSSClient instance.
To list objects, you must have the oss:ListObjects permission. For more information, see Attach a custom policy to a RAM user.

Background information

You can call the GetBucket (ListObjects) or GetBucketV2 (ListObjectsV2) operation to list up to 1,000 objects in a bucket at a time. You can specify list operation parameters to list objects based on your business requirements. For example, you can list all the objects after a specific position, list all objects and subdirectories in a specific directory, and list more than 1,000 objects by page. The GetBucket (ListObjects) and GetBucketV2 (ListObjectsV2) operations have some differences:

When you call the GetBucket (ListObjects) operation to list objects, the object owner information is included in the response.
When you call the GetBucketV2 (ListObjectsV2) operation to list objects, you can configure the fetchOwner parameter to specify whether to include the object owner information in the response.
Note
To list objects in a versioning-enabled bucket, we recommend that you call the GetBucketV2 (ListObjectsV2) operation.

The following tables describe the parameters that you can configure when you call the GetBucket (ListObjects) or GetBucketV2 (ListObjectsV2) operation to list objects.

GetBucket (ListObjects)

You can call the GetBucket (ListObjects) operation in one of the following formats:

ObjectListing listObjects(String bucketName): lists all objects in a bucket. By default, up to 100 objects can be listed in a single request.
ObjectListing listObjects(String bucketName, String prefix): lists objects whose names contain a specific prefix in a bucket. By default, up to 100 objects can be listed by a single request.
ObjectListing listObjects(ListObjectsRequest listObjectsRequest): lists objects that meet the specified conditions. You can use this format to list objects in a flexible manner.

The following table describes the parameters that you can specify when you call the GetBucket (ListObjects) operation.

Parameter	Description	Method
objectSummaries	The metadata of the objects that you want to list.	List<OSSObjectSummary> getObjectSummaries()
prefix	The prefix in the names of the objects that you want to list.	String getPrefix()
delimiter	The character used to group the objects that you want to list by name.	String getDelimiter()
marker	The position from which the list operation starts.	String getMarker()
maxKeys	The maximum number of objects that can be listed at a time.	int getMaxKeys()
nextMarker	The position from which the next list operation starts.	String getNextMarker()
isTruncated	Specifies whether the object listing is truncated. Valid values: false: All objects are listed without truncation. true: Only a part of the objects are listed.	boolean isTruncated()
commonPrefixes	A set of substrings of object names. Objects whose names end with the delimiter and contain the same prefix are grouped as a single result element in CommonPrefixes.	List<String> getCommonPrefixes()
encodingType	The encoding type of the object names in the response.	String getEncodingType()

GetBucketV2 (ListObjectsV2)

You can call the GetBucketV2 (ListObjectsV2) operation in one of the following formats:

ListObjectsV2Result listObjectsV2(String bucketName): lists all objects in a bucket. By default, up to 100 objects can be listed by a single request.
ListObjectsV2Result listObjectsV2(String bucketName, String prefix): lists objects whose names contain a specific prefix in a bucket. By default, up to 100 objects can be listed by a single request.
ListObjectsV2Result listObjectsV2(ListObjectsRequest listObjectsRequest): lists objects that meet the specified conditions. You can use this format to list objects in a flexible manner.

The following table describes the parameters that you can specify when you call the GetBucketV2 (ListObjectsV2) operation.

Parameter	Description	Method
objectSummaries	The metadata of the objects that you want to list.	List<OSSObjectSummary> getObjectSummaries()
prefix	The prefix in the names of the objects that you want to list.	String getPrefix()
delimiter	The character used to group the objects that you want to list by name.	String getDelimiter()
startAfter	The position from which the list operation starts.	String getStartAfter()
maxKeys	The maximum number of objects that can be listed at a time.	int getMaxKeys()
continuationToken	The position from which the list operation starts.	String getContinuationToken()
nextContinuationToken	The position from which the next list operation starts.	String getNextContinuationToken()
isTruncated	Specifies whether the object listing is truncated. Valid values: false: All objects are listed without truncation. true: Only a part of the objects are listed.	boolean isTruncated()
commonPrefixes	A set of substrings of object names. Objects whose names end with the delimiter and contain the same prefix are grouped as a single result element in CommonPrefixes.	List<String> getCommonPrefixes()
encodingType	The encoding type of the object names in the response.	String getEncodingType()
fetchOwner	Specifies whether to include the object owner information in the response. Valid values: true: The response includes the object owner information. false: The response does not include the object owner information.	String getFetchOwner()

List objects by using simple list

You can call the GetBucket (ListObjects) operation or the GetBucketV2 (ListObjectsV2) operation to list objects in a specific bucket.

Call the GetBucket (ListObjects) operation to list objects

The following sample code provides an example on how to call the GetBucket (ListObjects) operation to list objects in a specific bucket. By default, 100 objects are listed in a request.

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;
import java.util.List;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the prefix in the names of the objects that you want to list. Example: exampledir/object. 
        String keyPrefix = "exampledir/object";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            // List objects. If you do not specify keyPrefix, all objects in the bucket are listed. If you specify keyPrefix, the objects whose names contain the specified prefix are listed. 
            ObjectListing objectListing = ossClient.listObjects(bucketName, keyPrefix);
            List<OSSObjectSummary> sums = objectListing.getObjectSummaries();
            for (OSSObjectSummary s : sums) {
                System.out.println("\t" + s.getKey());
            }
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

Call the GetBucketV2 (ListObjectsV2) operation to list objects

The following sample code provides an example on how to call the GetBucketV2 (ListObjectsV2) operation to list objects in a specific bucket. By default, 100 objects are listed by a request.

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;
import java.util.List;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the prefix in the names of the objects that you want to list. Example: exampledir/object. 
        String keyPrefix = "exampledir/object";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            // List objects. If you do not specify keyPrefix, all objects in the bucket are listed. If you specify keyPrefix, the objects whose names contain the specified prefix are listed. 
            ListObjectsV2Result result = ossClient.listObjectsV2(bucketName, keyPrefix);
            List<OSSObjectSummary> ossObjectSummaries = result.getObjectSummaries();

            for (OSSObjectSummary s : ossObjectSummaries) {
                System.out.println("\t" + s.getKey());
            }
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

Call the ListObjectsRequest operation to list objects

You can specify parameters when you call the ListObjectsRequest operation to list objects in a flexible manner. The following table describes the parameters that you can specify when you call the ListObjectsRequest operation.

Parameter	Description	Method
prefix	The prefix that must be included in the names of the objects that you want to list.	setPrefix(String prefix)
delimiter	The character that is used to group the objects that you want to list by name. For example, you can set the delimiter to a forward slash (/). Objects whose names contain the same string that stretches from the specified prefix to the first occurrence of the forward slash (/) are grouped as a CommonPrefixes element. All objects whose names contain the CommonPrefixes elements are listed. You can use the delimiter parameter to manage and query objects in a hierarchical manner. This ensures more organized and intuitive query results.	setDelimiter(String delimiter)
marker	The position from which the list operation starts. Objects whose names are alphabetically after the value of marker are listed.	setMarker(String marker)
maxKeys	The maximum number of objects that can be listed at a time. After you specify this parameter, objects are listed in alphabetical order. Maximum value: 1000. Default value: 100.	setMaxKeys(Integer maxKeys)
encodingType	The encoding type of the object names in the response. Valid value: URL.	setEncodingType(String encodingType)

List a specific number of objects

The following sample code provides an example on how to list a specific number of objects in a bucket:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;
import java.util.List;

public class Demo {
    public static void main(String[] args){
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            // Specify the maximum number of objects that can be listed at a time. 
            final int maxKeys = 200;
            // List objects. 
            ObjectListing objectListing = ossClient.listObjects(new ListObjectsRequest(bucketName).withMaxKeys(maxKeys));
            List<OSSObjectSummary> sums = objectListing.getObjectSummaries();
            for (OSSObjectSummary s : sums) {
                System.out.println("\t" + s.getKey());
            }
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

List objects whose names contain a specific prefix

The following sample code provides an example on how to list objects whose names contain a specific prefix in a bucket:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;
import java.util.List;

public class Demo {
    public static void main(String[] args){
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the prefix in the names of the objects that you want to list. Example: exampledir/object. 
        String keyPrefix = "exampledir/object";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            // List objects whose names contain the specified prefix. By default, 100 objects are listed. 
            ObjectListing objectListing = ossClient.listObjects(new ListObjectsRequest(bucketName).withPrefix(keyPrefix));
            List<OSSObjectSummary> sums = objectListing.getObjectSummaries();
            for (OSSObjectSummary s : sums) {
                System.out.println("\t" + s.getKey());
            }
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

List objects whose names are alphabetically after the value of marker

The following sample code provides an example on how to list objects whose names are alphabetically after the value of marker:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;
import java.util.List;

public class Demo {
    public static void main(String[] args){
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the name of the object after which the list begins. If this parameter is specified, objects whose names are alphabetically after the value of marker are returned.   
        String marker = "ex";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            // List objects whose names are alphabetically after the object specified by marker. By default, 100 objects are listed. 
            ObjectListing objectListing = ossClient.listObjects(new ListObjectsRequest(bucketName).withMarker(marker));
            List<OSSObjectSummary> sums = objectListing.getObjectSummaries();
            for (OSSObjectSummary s : sums) {
                System.out.println("\t" + s.getKey());
            }
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

List all objects in a bucket by page

The following sample code provides an example on how to list all objects in a bucket by page. You can use maxKeys to specify the maximum number of objects that can be listed on each page.

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;
import java.util.List;

public class Demo {
    public static void main(String[] args){
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Set maxKeys to 200. 
        int maxKeys = 200;
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            String nextMarker = null;
            ObjectListing objectListing;

            do {
                objectListing = ossClient.listObjects(new ListObjectsRequest(bucketName).withMarker(nextMarker).withMaxKeys(maxKeys));

                List<OSSObjectSummary> sums = objectListing.getObjectSummaries();
                for (OSSObjectSummary s : sums) {
                    System.out.println("\t" + s.getKey());
                }

                nextMarker = objectListing.getNextMarker();

            } while (objectListing.isTruncated());
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

List objects whose names contain a specific prefix by page

The following sample code provides an example on how to list objects whose names contain a specific prefix by page:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;
import java.util.List;

public class Demo {
    public static void main(String[] args){
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Set maxKeys to 200. 
        int maxKeys = 200;
        // Specify the prefix in the names of the objects that you want to list. Example: exampledir/object. 
        String keyPrefix = "exampledir/object";
        // Specify the marker parameter. Example: objecttest.txt. 
        String nextMarker = "objecttest.txt";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            ObjectListing objectListing;

            do {
                objectListing = ossClient.listObjects(new ListObjectsRequest(bucketName).
                        withPrefix(keyPrefix).withMarker(nextMarker).withMaxKeys(maxKeys));

                List<OSSObjectSummary> sums = objectListing.getObjectSummaries();
                for (OSSObjectSummary s : sums) {
                    System.out.println("\t" + s.getKey());
                }

                nextMarker = objectListing.getNextMarker();

            } while (objectListing.isTruncated());

        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

List objects whose names are encoded by using a specific encoding type

If the name of an object contains one of the following characters, the object name must be URL-encoded before the object can be transmitted. OSS supports only URL encoding.

Single quotation marks (')
Double quotation marks (")
Ampersands (&)
Angle brackets (<>)
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The following sample code provides an example on how to list objects whose names are encoded by using a specific encoding type:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;
import java.net.URLDecoder;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Set maxKeys to 200. 
        int maxKeys = 200;
        // Specify the prefix in the names of the objects that you want to list. Example: exampledir/object. 
        String keyPrefix = "exampledir/object";
        // Specify the marker parameter. Example: objecttest.txt. 
        String nextMarker = "objecttest.txt";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            ObjectListing objectListing;

            do {
                ListObjectsRequest listObjectsRequest = new ListObjectsRequest(bucketName);
                listObjectsRequest.setPrefix(keyPrefix);
                listObjectsRequest.setMaxKeys(maxKeys);
                listObjectsRequest.setMarker(nextMarker);

                // Specify the encoding type of the object names. 
                listObjectsRequest.setEncodingType("url");

                objectListing = ossClient.listObjects(listObjectsRequest);

                // Decode the values of object keys in the response. 
                for (OSSObjectSummary objectSummary: objectListing.getObjectSummaries()) {
                    System.out.println("Key:" + URLDecoder.decode(objectSummary.getKey(), "UTF-8"));
                }

                // Decode the value of CommonPrefixes in the response. 
                for (String commonPrefixes: objectListing.getCommonPrefixes()) {
                    System.out.println("CommonPrefixes:" + URLDecoder.decode(commonPrefixes, "UTF-8"));
                }

                // Decode the value of nextMarker in the response. 
                if (objectListing.getNextMarker() != null) {
                    nextMarker = URLDecoder.decode(objectListing.getNextMarker(), "UTF-8");
                }
            } while (objectListing.isTruncated());
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

Call the ListObjectsV2Request operation to list objects

You can specify parameters when you call the ListObjectsV2Request operation to list objects in a flexible manner. For example, you can list a specific number of objects, objects whose names contain a specific prefix, or all objects in a bucket by page.

The following table describes the parameters that you can specify when you call the ListObjectsV2Request operation.

Parameter	Description	Method
prefix	The prefix that must be included in the names of the objects that you want to list.	setPrefix(String prefix)
delimiter	The character that is used to group the objects that you want to list by name. For example, you can set the delimiter to a forward slash (/). Objects whose names contain the same string that stretches from the specified prefix to the first occurrence of the forward slash (/) are grouped as a CommonPrefixes element. All objects whose names contain the CommonPrefixes elements are listed. You can use the delimiter parameter to manage and query objects in a hierarchical manner. This ensures more organized and intuitive query results.	setDelimiter(String delimiter)
maxKeys	The maximum number of objects that can be listed at a time. After you specify this parameter, objects are listed in alphabetical order. Maximum value: 1000. Default value: 100.	setMaxKeys(Integer maxKeys)
startAfter	The position from which the list operation starts. Objects whose names are alphabetically after the value of startAfter are listed.	setStartAfter(String startAfter)
continuationToken	The continuationToken that is used in this list operation.	setContinuationToken(String continuationToken)
encodingType	The encoding type of the object names in the response. Valid value: URL.	setEncodingType(String encodingType)
fetchOwner	Specifies whether to include the owner information in the response.	setFetchOwner(boolean fetchOwner )

List a specific number of objects

The following sample code provides an example on how to list a specific number of objects in a bucket:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;
import java.util.List;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the maximum number of objects that can be listed at a time. 
        int maxKeys = 200;
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            // List objects. By default, 100 objects are returned by a single request. In this example, up to 200 objects can be returned at a time. 
            ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName);
            listObjectsV2Request.setMaxKeys(maxKeys);
            ListObjectsV2Result result = ossClient.listObjectsV2(listObjectsV2Request);
            List<OSSObjectSummary> ossObjectSummaries = result.getObjectSummaries();

            for (OSSObjectSummary s : ossObjectSummaries) {
                System.out.println("\t" + s.getKey());
            }
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

List objects whose names contain a specific prefix

The following sample code provides an example on how to list objects whose names contain a specific prefix in a bucket:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;
import java.util.List;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the prefix in the names of the objects that you want to list. Example: exampledir/object. 
        String prefix = "exampledir/object";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            // List objects whose names contain the specified prefix. 
            ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName);
            listObjectsV2Request.setPrefix(prefix);
            ListObjectsV2Result result = ossClient.listObjectsV2(listObjectsV2Request);
            List<OSSObjectSummary> ossObjectSummaries = result.getObjectSummaries();

            for (OSSObjectSummary s : ossObjectSummaries) {
                System.out.println("\t" + s.getKey());
            }
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

List objects whose names are alphabetically after the value of startAfter

The following sample code provides an example on how to list objects whose names are alphabetically after the value of startAfter:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;
import java.util.List;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            // Specify the name of the object after which the list begins. If this parameter is specified, objects whose names are alphabetically after the value of start-after are returned.           
            ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName);
            listObjectsV2Request.setStartAfter("ex");
            ListObjectsV2Result result = ossClient.listObjectsV2(listObjectsV2Request);
            List<OSSObjectSummary> ossObjectSummaries = result.getObjectSummaries();

            for (OSSObjectSummary s : ossObjectSummaries) {
                System.out.println("\t" + s.getKey());
            }
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

List objects and their owner information

The following sample code provides an example on how to list objects and their owner information:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;
import java.util.List;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            // By default, the object owner information is not listed. To include the object owner information in the response, set the fetchOwner parameter to true. 
            ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName);
            listObjectsV2Request.setFetchOwner(true);
            ListObjectsV2Result result = ossClient.listObjectsV2(listObjectsV2Request);
            List<OSSObjectSummary> ossObjectSummaries = result.getObjectSummaries();

            for (OSSObjectSummary s : ossObjectSummaries) {
                System.out.println("\t" + s.getKey());
                if (s.getOwner() != null) {
                    System.out.println("owner id:" + s.getOwner().getId());
                    System.out.println("name:" + s.getOwner().getDisplayName());
                }
            }
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

List all objects in a bucket by page

The following sample code provides an example on how to list all objects in a bucket by page. You can use maxKeys to specify the maximum number of objects that can be listed on each page.

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;
import java.util.List;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the maximum number of objects that can be listed at a time. 
        int maxKeys = 200;
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            String nextContinuationToken = null;
            ListObjectsV2Result result = null;

            // List objects by page by using the nextContinuationToken parameter included in the response of the previous list operation. 
            do {
                ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName).withMaxKeys(maxKeys);
                listObjectsV2Request.setContinuationToken(nextContinuationToken);
                result = ossClient.listObjectsV2(listObjectsV2Request);

                List<OSSObjectSummary> sums = result.getObjectSummaries();
                for (OSSObjectSummary s : sums) {
                    System.out.println("\t" + s.getKey());
                }

                nextContinuationToken = result.getNextContinuationToken();

            } while (result.isTruncated());
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

List objects whose names contain a specific prefix by page

The following sample code provides an example on how to list objects whose names contain a specific prefix by page:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;
import java.util.List;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the prefix in the names of the objects that you want to list. Example: exampledir/object. 
        String keyPrefix = "exampledir/object";
        // Specify the maximum number of objects that can be listed at a time. 
        int maxKeys = 200;
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            String nextContinuationToken = null;
            ListObjectsV2Result result = null;

            // List the objects whose names contain the specified prefix by page. 
            do {
                ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName).withMaxKeys(maxKeys);
                listObjectsV2Request.setPrefix(keyPrefix);
                listObjectsV2Request.setContinuationToken(nextContinuationToken);
                result = ossClient.listObjectsV2(listObjectsV2Request);

                List<OSSObjectSummary> sums = result.getObjectSummaries();
                for (OSSObjectSummary s : sums) {
                    System.out.println("\t" + s.getKey());
                }

                nextContinuationToken = result.getNextContinuationToken();

            } while (result.isTruncated());
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

List objects whose names are encoded by using a specific encoding type

The following sample code provides an example on how to list objects whose names are encoded by using a specific encoding type:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;
import java.net.URLDecoder;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the prefix in the names of the objects that you want to list. Example: exampledir/object. 
        String keyPrefix = "exampledir/object";
        // Specify the maximum number of objects that can be listed at a time. 
        int maxKeys = 200;
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            String nextContinuationToken = null;
            ListObjectsV2Result result = null;

            // Specify that the returned results are URL-encoded. In this case, you must decode the values of the prefix, delimiter, startAfter, key, and commonPrefixes parameters in the response. 
            do {
                ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName).withMaxKeys(maxKeys);
                listObjectsV2Request.setPrefix(keyPrefix);
                listObjectsV2Request.setEncodingType("url");
                listObjectsV2Request.setContinuationToken(nextContinuationToken);
                result = ossClient.listObjectsV2(listObjectsV2Request);

                // Decode the value of prefix in the response. 
                if (result.getPrefix() != null) {
                    String prefix = URLDecoder.decode(result.getPrefix(), "UTF-8");
                    System.out.println("prefix: " + prefix);
                }

                // Decode the value of delimiter in the response. 
                if (result.getDelimiter() != null) {
                    String delimiter = URLDecoder.decode(result.getDelimiter(), "UTF-8");
                    System.out.println("delimiter: " + delimiter);
                }

                // Decode the value of startAfter in the response. 
                if (result.getStartAfter() != null) {
                    String startAfter = URLDecoder.decode(result.getStartAfter(), "UTF-8");
                    System.out.println("startAfter: " + startAfter);
                }

                // Decode the values of object keys in the response. 
                for (OSSObjectSummary s : result.getObjectSummaries()) {
                    String decodedKey = URLDecoder.decode(s.getKey(), "UTF-8");
                    System.out.println("key: " + decodedKey);
                }

                // Decode the value of CommonPrefixes in the response. 
                for (String commonPrefix: result.getCommonPrefixes()) {
                    String decodeCommonPrefix = URLDecoder.decode(commonPrefix, "UTF-8");
                    System.out.println("CommonPrefix:" + decodeCommonPrefix);
                }

                nextContinuationToken = result.getNextContinuationToken();

            } while (result.isTruncated());
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

List objects by directory

OSS uses a flat structure to store objects. A directory is a zero-byte object whose name ends with a forward slash (/). You can upload and download this object. By default, an object whose name ends with a forward slash (/) is displayed as a directory in the OSS console. For the complete sample code that is used to create directories, visit GitHub.

You can specify the delimiter and prefix parameters to list objects by directory.

If you set prefix to a directory name in the request, the objects and subdirectories whose names contain the prefix are listed.
If you specify a prefix and set delimiter to a forward slash (/) in the request, the objects and subdirectories whose names start with the specified prefix in the directory are listed. Each subdirectory is listed as a single result element in CommonPrefixes. The objects and directories in these subdirectories are not listed.

For example, a bucket contains the following objects: oss.jpg, fun/test.jpg, fun/movie/001.avi, and fun/movie/007.avi. The forward slash (/) is specified as the directory delimiter. The following examples describe how to list objects in simulated directories.

List all objects in the bucket

The following sample code provides an example on how to call the GetBucket (ListObjects) operation to list all objects in the bucket:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            // Create a request to list objects. 
            ListObjectsRequest listObjectsRequest = new ListObjectsRequest(bucketName);

            // List objects. 
            ObjectListing listing = ossClient.listObjects(listObjectsRequest);

            // Traverse all objects. 
            System.out.println("Objects:");
            for (OSSObjectSummary objectSummary : listing.getObjectSummaries()) {
                System.out.println(objectSummary.getKey());
            }

            // Traverse all CommonPrefix elements. 
            System.out.println("CommonPrefixes:");
            for (String commonPrefix : listing.getCommonPrefixes()) {
                System.out.println(commonPrefix);
            }
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

The following sample code provides an example on how to call the GetBucketV2 (ListObjectsV2) operation to list all objects in a bucket:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            // List objects. 
            ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName);
            ListObjectsV2Result result = ossClient.listObjectsV2(listObjectsV2Request);

            // Traverse all objects. 
            System.out.println("Objects:");
            for (OSSObjectSummary objectSummary : result.getObjectSummaries()) {
                System.out.println(objectSummary.getKey());
            }

            // Traverse all CommonPrefix elements. 
            System.out.println("CommonPrefixes:");
            for (String commonPrefix : result.getCommonPrefixes()) {
                System.out.println(commonPrefix);
            }
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

Response parameters

The following response is returned for the preceding two methods that list all objects in a bucket:

Objects:
fun/movie/001.avi
fun/movie/007.avi
fun/test.jpg
oss.jpg
CommonPrefixes:

List all objects in a directory

The following sample code provides an example on how to call the GetBucket (ListObjects) operation to list all objects in a directory:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            // Create a request to list objects. 
            ListObjectsRequest listObjectsRequest = new ListObjectsRequest(bucketName);
            // Set prefix to fun/ to list all objects in the fun/ directory. 
            listObjectsRequest.setPrefix("fun/");

            // Lists all objects in the fun/ directory. 
            ObjectListing listing = ossClient.listObjects(listObjectsRequest);

            // Traverse all objects. 
            System.out.println("Objects:");
            for (OSSObjectSummary objectSummary : listing.getObjectSummaries()) {
                System.out.println(objectSummary.getKey());
            }

            // Traverse all CommonPrefix elements. 
            System.out.println("\nCommonPrefixes:");
            for (String commonPrefix : listing.getCommonPrefixes()) {
                System.out.println(commonPrefix);
            }
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

The following sample code provides an example on how to call the GetBucketV2 (ListObjectsV2) operation to list all objects in a specific directory:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            // Create a ListObjectsV2Request request to list objects. 
            ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName);

            // Set prefix to fun/ to list all objects in the fun/ directory. 
            listObjectsV2Request.setPrefix("fun/");

            // Initiate the request. 
            ListObjectsV2Result result = ossClient.listObjectsV2(listObjectsV2Request);

            // Traverse all objects. 
            System.out.println("Objects:");
            for (OSSObjectSummary objectSummary : result.getObjectSummaries()) {
                System.out.println(objectSummary.getKey());
            }

            // Traverse all CommonPrefix elements. 
            System.out.println("\nCommonPrefixes:");
            for (String commonPrefix : result.getCommonPrefixes()) {
                System.out.println(commonPrefix);
            }
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

The following response is returned for the preceding two operations that list all objects in the specified directory:
```
Objects:
fun/movie/001.avi
fun/movie/007.avi
fun/test.jpg
CommonPrefixes:                    
```

List objects and subdirectories in a specific directory

The following sample code provides an example on how to call the GetBucket (ListObjects) operation to list objects and subdirectories in a specific directory:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            // Create a request to list objects. 
            ListObjectsRequest listObjectsRequest = new ListObjectsRequest(bucketName);

            // Set the delimiter to a forward slash (/). 
            listObjectsRequest.setDelimiter("/");

            // List all objects and subdirectories in the fun/ directory. 
            listObjectsRequest.setPrefix("fun/");

            ObjectListing listing = ossClient.listObjects(listObjectsRequest);

            // Traverse all objects. 
            System.out.println("Objects:");
            // In the response, objectSummaries lists the objects in the fun/ directory. 
            for (OSSObjectSummary objectSummary : listing.getObjectSummaries()) {
                System.out.println(objectSummary.getKey());
            }

            // Traverse all CommonPrefix elements. 
            System.out.println("\nCommonPrefixes:");
            // CommonPrefixs lists all subdirectories in the fun/ directory. The fun/movie/001.avi and fun/movie/007.avi objects are not listed because they are in the movie/ subdirectory of the fun/ directory. 
            for (String commonPrefix : listing.getCommonPrefixes()) {
                System.out.println(commonPrefix);
            }
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

The following sample code provides an example on how to call the GetBucketV2 (ListObjectsV2) operation to list objects and subdirectories in a directory:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            // Create a ListObjectsV2Request request to list objects. 
            ListObjectsV2Request listObjectsV2Request = new ListObjectsV2Request(bucketName);

            // Set Prefix to fun/ to list all objects and subdirectories in the fun/ directory. 
            listObjectsV2Request.setPrefix("fun/");

            // Set the delimiter to a forward slash (/). 
            listObjectsV2Request.setDelimiter("/");

            // Initiate the request. 
            ListObjectsV2Result result = ossClient.listObjectsV2(listObjectsV2Request);

            // Traverse all objects. 
            System.out.println("Objects:");
            // In the response, objectSummaries lists the objects in the fun/ directory. 
            for (OSSObjectSummary objectSummary : result.getObjectSummaries()) {
                System.out.println(objectSummary.getKey());
            }

            // Traverse all CommonPrefix elements. 
            System.out.println("\nCommonPrefixes:");
            // CommonPrefixs lists all subdirectories in the fun/ directory. The fun/movie/001.avi and fun/movie/007.avi objects are not listed because they are in the movie/ subdirectory of the fun/ directory. 
            for (String commonPrefix : result.getCommonPrefixes()) {
                System.out.println(commonPrefix);
            }
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }
}

The following response is returned when you call the preceding two operations to list objects and subdirectories in the specified directory:
```
Objects:
fun/test.jpg

CommonPrefixes:
fun/movie/                    
```

List the sizes of objects in a specific directory

The following sample code provides an example on how to call the GetBucket (ListObjects) operation to list the sizes of objects in a specific directory:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;
import java.util.List;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the prefix in the names of the objects that you want to list. Example: exampledir/object. If you want to traverse the sizes of objects and directories in the root directory, leave this parameter empty. 
        String keyPrefix = "exampledir/object";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build(););

        try {
            ObjectListing objectListing = null;
            do {
                // By default, 100 objects or directories are listed at a time. 
                ListObjectsRequest request = new ListObjectsRequest(bucketName).withDelimiter("/").withPrefix(keyPrefix);
                if (objectListing != null) {
                    request.setMarker(objectListing.getNextMarker());
                }
                objectListing = ossClient.listObjects(request);
                List<String> folders = objectListing.getCommonPrefixes();
                for (String folder : folders) {
                    System.out.println(folder + " : " + (calculateFolderLength(ossClient, bucketName, folder) / 1024) + "KB");
                }
                List<OSSObjectSummary> sums = objectListing.getObjectSummaries();
                for (OSSObjectSummary s : sums) {
                    System.out.println(s.getKey() + " : " + (s.getSize() / 1024) + "KB");
                }
            } while (objectListing.isTruncated());
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }

    // List the sizes of objects in a specific directory in a bucket. 
    private static long calculateFolderLength(OSS ossClient, String bucketName, String folder) {
        long size = 0L;
        ObjectListing objectListing = null;
        do {
            // The default value of MaxKeys is 100. The maximum value of MaxKeys is 1000. 
            ListObjectsRequest request = new ListObjectsRequest(bucketName).withPrefix(folder).withMaxKeys(1000);
            if (objectListing != null) {
                request.setMarker(objectListing.getNextMarker());
            }
            objectListing = ossClient.listObjects(request);
            List<OSSObjectSummary> sums = objectListing.getObjectSummaries();
            for (OSSObjectSummary s : sums) {
                size += s.getSize();
            }
        } while (objectListing.isTruncated());
        return size;
    }
}

The following sample code provides an example on how to call the GetBucketV2 (ListObjectsV2) operation to list the sizes of objects in a directory:

import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;import com.aliyun.oss.OSS;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.model.*;
import java.util.List;

public class Demo {
    public static void main(String[] args) throws Exception {
        // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. Example: examplebucket. 
        String bucketName = "examplebucket";
        // Specify the prefix in the names of the objects that you want to list. Example: exampledir/object. If you want to traverse the sizes of objects and directories in the root directory, leave this parameter empty. 
        String keyPrefix = "exampledir/object";
        // Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. 
        String region = "cn-hangzhou";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            ListObjectsV2Result result = null;
            do {
                // By default, 100 objects or directories are listed at a time. 
                ListObjectsV2Request request = new ListObjectsV2Request(bucketName).withDelimiter("/").withPrefix(keyPrefix);
                if (result != null) {
                    request.setContinuationToken(result.getNextContinuationToken());
                }
                result = ossClient.listObjectsV2(request);
                List<String> folders = result.getCommonPrefixes();
                for (String folder : folders) {
                    System.out.println(folder + " : " + (calculateFolderLength(ossClient, bucketName, folder) / 1024) + "KB");
                }
                List<OSSObjectSummary> sums = result.getObjectSummaries();
                for (OSSObjectSummary s : sums) {
                    System.out.println(s.getKey() + " : " + (s.getSize() / 1024) + "KB");
                }
            } while (result.isTruncated());
        } catch (OSSException oe) {
            System.out.println("Caught an OSSException, which means your request made it to OSS, "
                    + "but was rejected with an error response for some reason.");
            System.out.println("Error Message:" + oe.getErrorMessage());
            System.out.println("Error Code:" + oe.getErrorCode());
            System.out.println("Request ID:" + oe.getRequestId());
            System.out.println("Host ID:" + oe.getHostId());
        } catch (ClientException ce) {
            System.out.println("Caught an ClientException, which means the client encountered "
                    + "a serious internal problem while trying to communicate with OSS, "
                    + "such as not being able to access the network.");
            System.out.println("Error Message:" + ce.getMessage());
        } finally {
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }

    // List the sizes of objects in a specific directory in a bucket. 
    private static long calculateFolderLength(OSS ossClient, String bucketName, String folder) {
        long size = 0L;
        ListObjectsV2Result result = null;
        do {
            // The default value of MaxKeys is 100. The maximum value of MaxKeys is 1000. 
            ListObjectsV2Request request = new ListObjectsV2Request(bucketName).withPrefix(folder).withMaxKeys(1000);
            if (result != null) {
                request.setContinuationToken(result.getNextContinuationToken());
            }
            result = ossClient.listObjectsV2(request);
            List<OSSObjectSummary> sums = result.getObjectSummaries();
            for (OSSObjectSummary s : sums) {
                size += s.getSize();
            }
        } while (result.isTruncated());
        return size;
    }
}

References

For the complete sample code that is used to list objects, visit GitHub.
For more information about the API operations that you can call to list objects, see GetBucket (ListObjects) and ListObjectsV2 (GetBucketV2).
For more information about how to list and manage LiveChannels, see Manage LiveChannels.