Object Storage Service:Use MetaSearch to search for OSS objects based on metadata attributes

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.ArrayList;
import java.util.List;

public class Demo {

    // In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
    private static String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
    // Specify the name of the bucket. Example: examplebucket. 
    private static String bucketName = "examplebucket";

    public static void main(String[] args) throws Exception {
        // 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 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 {
            // Query objects that meet specific conditions and list information about the objects based on specific fields and sorting methods. 
            int maxResults = 20;
            // Query objects that are smaller than 1,048,576 bytes in size, return up to 20 objects at a time, and sort the objects in ascending order. 
            String query = "{\"Field\": \"Size\",\"Value\": \"1048576\",\"Operation\": \"lt\"}";
            String sort = "Size";
            DoMetaQueryRequest doMetaQueryRequest = new DoMetaQueryRequest(bucketName, maxResults, query, sort);
            Aggregation aggregationRequest = new Aggregation();
            Aggregations aggregations = new Aggregations();
            List<Aggregation> aggregationList = new ArrayList<Aggregation>();
            // Specify the name of the field that is used in the aggregate operation. 
            aggregationRequest.setField("Size");
            // Specify the operator that is used in the aggregate operation. max indicates the maximum value. 
            aggregationRequest.setOperation("max");
            aggregationList.add(aggregationRequest);
            aggregations.setAggregation(aggregationList);

            // Specify the aggregate operation. 
            doMetaQueryRequest.setAggregations(aggregations);
            doMetaQueryRequest.setOrder(SortOrder.ASC);
            DoMetaQueryResult doMetaQueryResult = ossClient.doMetaQuery(doMetaQueryRequest);
            if(doMetaQueryResult.getFiles() != null){
                for(ObjectFile file : doMetaQueryResult.getFiles().getFile()){
                    System.out.println("Filename: " + file.getFilename());
                    // Query the ETag values that are used to identify the content of the objects. 
                    System.out.println("ETag: " + file.getETag());
                    // Query the access control list (ACL) of the objects.
                    System.out.println("ObjectACL: " + file.getObjectACL());
                    // Query the type of the objects. 
                    System.out.println("OssObjectType: " + file.getOssObjectType());
                    // Query the storage class of the objects. 
                    System.out.println("OssStorageClass: " + file.getOssStorageClass());
                    // Query the number of tags of the objects. 
                    System.out.println("TaggingCount: " + file.getOssTaggingCount());
                    if(file.getOssTagging() != null){
                        for(Tagging tag : file.getOssTagging().getTagging()){
                            System.out.println("Key: " + tag.getKey());
                            System.out.println("Value: " + tag.getValue());
                        }
                    }
                    if(file.getOssUserMeta() != null){
                        for(UserMeta meta : file.getOssUserMeta().getUserMeta()){
                            System.out.println("Key: " + meta.getKey());
                            System.out.println("Value: " + meta.getValue());
                        }
                    }
                }
            } else if(doMetaQueryResult.getAggregations() != null){
                for(Aggregation aggre : doMetaQueryResult.getAggregations().getAggregation()){
                    // Query the name of the aggregation field. 
                    System.out.println("Field: " + aggre.getField());
                    // Query the aggregation operator. 
                    System.out.println("Operation: " + aggre.getOperation());
                    // Query the values of the aggregate operations. 
                    System.out.println("Value: " + aggre.getValue());
                    if(aggre.getGroups() != null && aggre.getGroups().getGroup().size() > 0){
                        // Query the values of the aggregation operations by group. 
                        System.out.println("Groups value: " + aggre.getGroups().getGroup().get(0).getValue());
                        // Query the total number of the aggregation operations by group. 
                        System.out.println("Groups count: " + aggre.getGroups().getGroup().get(0).getCount());
                    }
                }
            } else {
                System.out.println("NextToken: " + doMetaQueryResult.getNextToken());
            }
        } catch (OSSException oe) {
            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("Error Message: " + ce.getMessage());
        } finally {
            // Shut down the OSSClient instance. 
            ossClient.shutdown();
        }
    }

# -*- coding: utf-8 -*-
import oss2
from oss2.credentials import EnvironmentVariableCredentialsProvider
from oss2.models import MetaQuery, AggregationsRequest
# 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. 
auth = oss2.ProviderAuthV4(EnvironmentVariableCredentialsProvider())

# Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. 
endpoint = "https://oss-cn-hangzhou.aliyuncs.com"
# Specify the ID of the region that maps to the endpoint. Example: cn-hangzhou. This parameter is required if you use the signature algorithm V4.
region = "cn-hangzhou"

# Specify the name of the bucket. Example: examplebucket. 
bucket = oss2.Bucket(auth, endpoint, "examplebucket", region=region)

# Query objects that meet specific conditions and list the object information based on specific fields and sorting methods. 
# Query objects that are smaller than 1 MB, return up to 10 objects at a time, and sort the objects in ascending order. 
do_meta_query_request = MetaQuery(max_results=10, query='{"Field": "Size","Value": "1048576","Operation": "lt"}', sort='Size', order='asc')
result = bucket.do_bucket_meta_query(do_meta_query_request)

# Display the object names. 
print(result.files[0].file_name)
# Display the ETags of the objects. 
print(result.files[0].etag)
# Display the types of the objects. 
print(result.files[0].oss_object_type)
# Display the storage classes of the objects. 
print(result.files[0].oss_storage_class)
# Display the CRC-64 values of the objects. 
print(result.files[0].oss_crc64)
# Display the access control lists (ACLs) of the objects. 
print(result.files[0].object_acl)

package main

import (
	"fmt"
	"os"

	"github.com/aliyun/aliyun-oss-go-sdk/oss"
)

func main() {
	// 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. 
	provider, err := oss.NewEnvironmentVariableCredentialsProvider()
	if err != nil {
		fmt.Println("Error:", err)
		os.Exit(-1)
	}

	// Create an OSSClient instance. 
        // Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. Specify your actual endpoint. 
	// 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. Specify the actual region.
	clientOptions := []oss.ClientOption{oss.SetCredentialsProvider(&provider)}
	clientOptions = append(clientOptions, oss.Region("yourRegion"))
	// Specify the version of the signature algorithm.
	clientOptions = append(clientOptions, oss.AuthVersion(oss.AuthV4))
	client, err := oss.New("yourEndpoint", "", "", clientOptions...)
	if err != nil {
		fmt.Println("Error:", err)
		os.Exit(-1)
	}
	// Query objects that are larger than 30 bytes in size, return up to 10 objects at the same time, and then sort the objects in ascending order. 
	query := oss.MetaQuery{
		NextToken:  "",
		MaxResults: 10,
		Query:      `{"Field": "Size","Value": "30","Operation": "gt"}`,
		Sort:       "Size",
		Order:      "asc",
	}
	// Query objects that match the specified conditions and list object information based on the specified fields and sorting methods. 
	result, err := client.DoMetaQuery("examplebucket", query)
	if err != nil {
		fmt.Println("Error:", err)
		os.Exit(-1)
	}
	fmt.Printf("NextToken:%s\n", result.NextToken)
	for _, file := range result.Files {
		fmt.Printf("File name: %s\n", file.Filename)
		fmt.Printf("size: %d\n", file.Size)
		fmt.Printf("File Modified Time:%s\n", file.FileModifiedTime)
		fmt.Printf("Oss Object Type:%s\n", file.OssObjectType)
		fmt.Printf("Oss Storage Class:%s\n", file.OssStorageClass)
		fmt.Printf("Object ACL:%s\n", file.ObjectACL)
		fmt.Printf("ETag:%s\n", file.ETag)
		fmt.Printf("Oss CRC64:%s\n", file.OssCRC64)
		fmt.Printf("Oss Tagging Count:%d\n", file.OssTaggingCount)
		for _, tagging := range file.OssTagging {
			fmt.Printf("Oss Tagging Key:%s\n", tagging.Key)
			fmt.Printf("Oss Tagging Value:%s\n", tagging.Value)
		}
		for _, userMeta := range file.OssUserMeta {
			fmt.Printf("Oss User Meta Key:%s\n", userMeta.Key)
			fmt.Printf("Oss User Meta Key Value:%s\n", userMeta.Value)
		}
	}
}