如何通過JavaSDK列舉Bucket下的檔案 - Object Storage Service

本文介紹如何在開啟版本控制狀態下列舉儲存空間下（Bucket）的所有檔案（Object）、指定個數的檔案、指定首碼的檔案等。

注意事項

本文以華東1（杭州）外網Endpoint為例。如果您希望通過與OSS同地區的其他阿里雲產品訪問OSS，請使用內網Endpoint。關於OSS支援的Region與Endpoint的對應關係，請參見OSS訪問網域名稱、資料中心、開放連接埠。
本文以從環境變數讀取存取憑證為例。如何配置訪問憑證，請參見Java配置訪問憑證。
本文以OSS網域名稱建立OSSClient為例。如果您希望通過自訂網域名、STS等方式建立OSSClient，請參見建立OSSClient。
要列舉檔案，您必須有oss:ListObjectVersions許可權。具體操作，請參見為RAM使用者授權自訂的權限原則。

列舉Bucket中所有Object的資訊

以下代碼用於列舉指定Bucket中包括刪除標記（Delete Marker）在內的所有Object的版本資訊。

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.*;

public class Demo {
    public static void main(String[] args) throws Exception {
        // Endpoint以華東1（杭州）為例，其它Region請按實際情況填寫。
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // 從環境變數中擷取訪問憑證。運行本程式碼範例之前，請確保已設定環境變數OSS_ACCESS_KEY_ID和OSS_ACCESS_KEY_SECRET。
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // 填寫Bucket名稱，例如examplebucket。
        String bucketName = "examplebucket";
        // 填寫Bucket所在地區。以華東1（杭州）為例，Region填寫為cn-hangzhou。
        String region = "cn-hangzhou";

        // 建立OSSClient執行個體。
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);        
        OSS ossClient = OSSClientBuilder.create()
        .endpoint(endpoint)
        .credentialsProvider(credentialsProvider)
        .clientConfiguration(clientBuilderConfiguration)
        .region(region)               
        .build();

        try {
            // 列舉包括刪除標記在內的所有Object的版本資訊。
            String nextKeyMarker = null;
            String nextVersionMarker = null;
            VersionListing versionListing = null;
            do {
                ListVersionsRequest listVersionsRequest = new ListVersionsRequest()
                        .withBucketName(bucketName)
                        .withKeyMarker(nextKeyMarker)
                        .withVersionIdMarker(nextVersionMarker);

                versionListing = ossClient.listVersions(listVersionsRequest);
                for (OSSVersionSummary ossVersion : versionListing.getVersionSummaries()) {
                    System.out.println("key name: " + ossVersion.getKey());
                    System.out.println("versionid: " + ossVersion.getVersionId());
                    System.out.println("Is latest: " + ossVersion.isLatest());
                    System.out.println("Is delete marker: " + ossVersion.isDeleteMarker());
                }

                nextKeyMarker = versionListing.getNextKeyMarker();
                nextVersionMarker = versionListing.getNextVersionIdMarker();
            } while (versionListing.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();
            }
        }
    }
}

列舉指定首碼Object的版本資訊

以下代碼用於列舉指定首碼Object的版本資訊。

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.internal.OSSConstants;
import com.aliyun.oss.model.*;

public class Demo {
    public static void main(String[] args) throws Exception {
        // Endpoint以華東1（杭州）為例，其它Region請按實際情況填寫。
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // 從環境變數中擷取訪問憑證。運行本程式碼範例之前，請確保已設定環境變數OSS_ACCESS_KEY_ID和OSS_ACCESS_KEY_SECRET。
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // 填寫Bucket名稱，例如examplebucket。
        String bucketName = "examplebucket";

        // 建立OSSClient執行個體。
        OSS ossClient = new OSSClientBuilder().build(endpoint, credentialsProvider);

        try {
            // 指定列舉以"test-"為首碼的Object的版本資訊。
            String prefix = "test-";
            String nextKeyMarker = null;
            String nextVersionMarker = null;
            VersionListing versionListing = null;
            do {
                ListVersionsRequest listVersionsRequest = new ListVersionsRequest()
                        .withBucketName(bucketName)
                        .withKeyMarker(nextKeyMarker)
                        .withVersionIdMarker(nextVersionMarker)
                        .withEncodingType(OSSConstants.URL_ENCODING)
                        .withPrefix(prefix);

                versionListing = ossClient.listVersions(listVersionsRequest);
                // 查看Object的版本資訊。
                for (OSSVersionSummary ossVersion : versionListing.getVersionSummaries()) {
                    System.out.println("key name: " + ossVersion.getKey());
                    System.out.println("versionid: " + ossVersion.getVersionId());
                    System.out.println("Is latest: " + ossVersion.isLatest());
                    System.out.println("Is delete marker: " + ossVersion.isDeleteMarker());
                }

                nextKeyMarker = versionListing.getNextKeyMarker();
                nextVersionMarker = versionListing.getNextVersionIdMarker();
            } while (versionListing.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();
            }
        }
    }
}

列舉指定個數Object的版本資訊

以下代碼用於列舉指定個數Object的版本資訊。

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.*;

public class Demo {
    public static void main(String[] args) throws Exception {
        // Endpoint以華東1（杭州）為例，其它Region請按實際情況填寫。
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // 從環境變數中擷取訪問憑證。運行本程式碼範例之前，請確保已設定環境變數OSS_ACCESS_KEY_ID和OSS_ACCESS_KEY_SECRET。
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // 填寫Bucket名稱，例如examplebucket。
        String bucketName = "examplebucket";

        // 建立OSSClient執行個體。
        OSS ossClient = new OSSClientBuilder().build(endpoint, credentialsProvider);

        try {
            // 指定最多返回200個結果。
            ListVersionsRequest listVersionsRequest = new ListVersionsRequest()
                    .withBucketName(bucketName)
                    .withMaxResults(200);

            VersionListing versionListing = ossClient.listVersions(listVersionsRequest);
            for (OSSVersionSummary ossVersion : versionListing.getVersionSummaries()) {
                System.out.println("key name: " + ossVersion.getKey());
                // 在未開啟版本控制的情況下，VersionId為none。
                System.out.println("versionid: " + ossVersion.getVersionId());
                System.out.println("Is latest: " + ossVersion.isLatest());
                System.out.println("Is delete marker: " + ossVersion.isDeleteMarker());
            }
        } 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();
            }
        }
    }
}

分頁列舉所有Object的版本資訊

以下代碼用於分頁列舉所有Object的版本資訊。

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.*;

public class Demo {
    public static void main(String[] args) throws Exception {
        // Endpoint以華東1（杭州）為例，其它Region請按實際情況填寫。
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // 從環境變數中擷取訪問憑證。運行本程式碼範例之前，請確保已設定環境變數OSS_ACCESS_KEY_ID和OSS_ACCESS_KEY_SECRET。
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // 填寫Bucket名稱，例如examplebucket。
        String bucketName = "examplebucket";
        // 設定每頁列舉200個檔案。
        int maxKeys = 200;

        // 建立OSSClient執行個體。
        OSS ossClient = new OSSClientBuilder().build(endpoint, credentialsProvider);

        try {
            // 分頁列舉所有Object的版本資訊。
            String nextKeyMarker = null;
            String nextVersionMarker = null;
            VersionListing versionListing = null;
            do {
                ListVersionsRequest listVersionsRequest = new ListVersionsRequest()
                        .withBucketName(bucketName)
                        .withKeyMarker(nextKeyMarker)
                        .withMaxResults(maxKeys)
                        .withVersionIdMarker(nextVersionMarker);

                versionListing = ossClient.listVersions(listVersionsRequest);
                for (OSSVersionSummary ossVersion : versionListing.getVersionSummaries()) {
                    System.out.println("key name: " + ossVersion.getKey());
                    System.out.println("versionid: " + ossVersion.getVersionId());
                    System.out.println("Is latest: " + ossVersion.isLatest());
                    System.out.println("Is delete marker: " + ossVersion.isDeleteMarker());
                }

                nextKeyMarker = versionListing.getNextKeyMarker();
                nextVersionMarker = versionListing.getNextVersionIdMarker();
            } while (versionListing.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();
            }
        }
    }
}

列舉名稱中包含特殊字元的Object

如果檔案名稱含有以下特殊字元，需要進行編碼傳輸。OSS目前僅支援URL編碼。

單引號（' '）
雙引號（" "）
and符號（&）
角括弧（< >）
頓號（、）
中文

以下代碼用於列舉名稱中包含特殊字元的Object。

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.internal.OSSConstants;
import com.aliyun.oss.model.*;

public class Demo {
    public static void main(String[] args) throws Exception {
        // Endpoint以華東1（杭州）為例，其它Region請按實際情況填寫。
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // 從環境變數中擷取訪問憑證。運行本程式碼範例之前，請確保已設定環境變數OSS_ACCESS_KEY_ID和OSS_ACCESS_KEY_SECRET。
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // 填寫Bucket名稱，例如examplebucket。
        String bucketName = "examplebucket";

        // 建立OSSClient執行個體。
        OSS ossClient = new OSSClientBuilder().build(endpoint, credentialsProvider);

        try {
            // 指定返回結果以URL編碼進行傳輸。
            String nextKeyMarker = null;
            String nextVersionMarker = null;
            VersionListing versionListing = null;
            do {
                ListVersionsRequest listVersionsRequest = new ListVersionsRequest()
                        .withBucketName(bucketName)
                        .withKeyMarker(nextKeyMarker)
                        .withVersionIdMarker(nextVersionMarker)
                        .withEncodingType(OSSConstants.URL_ENCODING);

                versionListing = ossClient.listVersions(listVersionsRequest);
                // 查看Object的版本資訊。
                for (OSSVersionSummary ossVersion : versionListing.getVersionSummaries()) {
                    System.out.println("key name: " + ossVersion.getKey());
                    System.out.println("versionid: " + ossVersion.getVersionId());
                    System.out.println("Is latest: " + ossVersion.isLatest());
                    System.out.println("Is delete marker: " + ossVersion.isDeleteMarker());
                }

                nextKeyMarker = versionListing.getNextKeyMarker();
                nextVersionMarker = versionListing.getNextVersionIdMarker();
            } while (versionListing.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();
            }
        }
    }
}

檔案夾功能

OSS沒有檔案夾的概念，所有元素都是以檔案來儲存。建立檔案夾本質上來說是建立了一個大小為0並以正斜線（/）結尾的檔案。這個檔案可以被上傳和下載，控制台會對以正斜線（/）結尾的檔案以檔案夾的方式展示。

通過delimiter和prefix兩個參數可以類比檔案夾功能：

如果設定prefix為某個檔案夾名稱，則會列舉以此prefix開頭的檔案，即該檔案夾下所有的檔案和子檔案夾（目錄）均顯示為Object。
如果在設定了prefix的情況下，將delimiter設定為正斜線（/），則只列舉該檔案夾下的檔案和子檔案夾（目錄），該檔案夾下的子檔案夾（目錄）顯示為CommonPrefixes，子檔案夾下的檔案和檔案夾不顯示。

假設儲存空間中包含檔案oss.jpg、fun/test.jpg、fun/movie/001.avi和fun/movie/007.avi，以正斜線（/）作為檔案夾的分隔字元。以下樣本說明了如何通過類比檔案夾的方式列舉檔案。

列舉根目錄下的Object的版本資訊

以下代碼用於列舉根目錄下的Object的版本資訊。

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.internal.OSSConstants;
import com.aliyun.oss.model.*;

public class Demo {
    public static void main(String[] args) throws Exception {
        // Endpoint以華東1（杭州）為例，其它Region請按實際情況填寫。
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // 從環境變數中擷取訪問憑證。運行本程式碼範例之前，請確保已設定環境變數OSS_ACCESS_KEY_ID和OSS_ACCESS_KEY_SECRET。
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // 填寫Bucket名稱，例如examplebucket。
        String bucketName = "examplebucket";

        // 建立OSSClient執行個體。
        OSS ossClient = new OSSClientBuilder().build(endpoint, credentialsProvider);

        try {
            // 指定delimiter參數為正斜線（/），將會列舉根目錄下的Object的版本資訊以及檔案夾名稱。
            String delimiter = "/";
            String nextKeyMarker = null;
            String nextVersionMarker = null;
            VersionListing versionListing = null;
            do {
                ListVersionsRequest listVersionsRequest = new ListVersionsRequest()
                        .withBucketName(bucketName)
                        .withKeyMarker(nextKeyMarker)
                        .withVersionIdMarker(nextVersionMarker)
                        .withEncodingType(OSSConstants.URL_ENCODING)
                        .withDelimiter(delimiter);

                versionListing = ossClient.listVersions(listVersionsRequest);
                // 查看Object的版本資訊。
                for (OSSVersionSummary ossVersion : versionListing.getVersionSummaries()) {
                    System.out.println("key name: " + ossVersion.getKey());
                    System.out.println("versionid: " + ossVersion.getVersionId());
                    System.out.println("Is latest: " + ossVersion.isLatest());
                    System.out.println("Is delete marker: " + ossVersion.isDeleteMarker());
                }
                // 查看根目錄下以正斜線（/）結尾的檔案夾名稱。
                for (String commonPrefix : versionListing.getCommonPrefixes()) {
                    System.out.println("commonPrefix: " + commonPrefix);
                }

                nextKeyMarker = versionListing.getNextKeyMarker();
                nextVersionMarker = versionListing.getNextVersionIdMarker();
            } while (versionListing.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();
            }
        }
    }
}

返回結果

key name: oss.jpg
versionid: CAEQEhiBgMCw8Y7FqBciIGIzMDE3MTEzOWRiMDRmZmFhMmRlMjljZWI0MWU4****
Is latest: true
Is delete marker: false

commonPrefix: fun/

以下代碼用於列舉指定目錄下的檔案和子目錄。

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.internal.OSSConstants;
import com.aliyun.oss.model.*;

public class Demo {
    public static void main(String[] args) throws Exception {
        // Endpoint以華東1（杭州）為例，其它Region請按實際情況填寫。
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // 從環境變數中擷取訪問憑證。運行本程式碼範例之前，請確保已設定環境變數OSS_ACCESS_KEY_ID和OSS_ACCESS_KEY_SECRET。
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // 填寫Bucket名稱，例如examplebucket。
        String bucketName = "examplebucket";

        // 建立OSSClient執行個體。
        OSS ossClient = new OSSClientBuilder().build(endpoint, credentialsProvider);

        try {
            // 設定prefix參數來擷取fun目錄下的所有檔案與檔案夾，同時設定delimiter參數為正斜線（/）作為檔案夾的分隔字元。
            String prefix = "fun/";  
            String delimiter = "/";
            String nextKeyMarker = null;
            String nextVersionMarker = null;
            VersionListing versionListing = null;
            do {
                ListVersionsRequest listVersionsRequest = new ListVersionsRequest()
                        .withBucketName(bucketName)
                        .withKeyMarker(nextKeyMarker)
                        .withVersionIdMarker(nextVersionMarker)
                        .withEncodingType(OSSConstants.URL_ENCODING)
                        .withDelimiter(delimiter)
                        .withPrefix(prefix);

                versionListing = ossClient.listVersions(listVersionsRequest);
                // 查看Object的版本資訊。
                for (OSSVersionSummary ossVersion : versionListing.getVersionSummaries()) {
                    System.out.println("key name: " + ossVersion.getKey());
                    System.out.println("versionid: " + ossVersion.getVersionId());
                    System.out.println("Is latest: " + ossVersion.isLatest());
                    System.out.println("Is delete marker: " + ossVersion.isDeleteMarker());
                }
                // 查看fun目錄下的子目錄名稱。
                for (String commonPrefix : versionListing.getCommonPrefixes()) {
                    System.out.println("commonPrefix: " + commonPrefix);
                }

                nextKeyMarker = versionListing.getNextKeyMarker();
                nextVersionMarker = versionListing.getNextVersionIdMarker();
            } while (versionListing.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();
            }
        }
    }
}

返回結果：

key name: fun/test.jpg
versionid: CAEQEhiBgIC48Y7FqBciIDU4NjAzMjczMTY5NDRjYmVhNGY4NTM2YTdjY2Ji****
Is latest: true
Is delete marker: false

commonPrefix: fun/movie/