Object Storage Service:Data indexing

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";
    // We recommend that you do not save access credentials in the project code. Otherwise, access credentials may be leaked. As a result, the security of all resources in your account is compromised. In this example, access credentials are obtained from environment variables. You need to configure environment variables before you run the sample code. 
    EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
    // Specify the name of the bucket. Example: examplebucket. 
    private static String bucketName = "examplebucket";

    public static void main(String[] args) {
        // Create an OSSClient instance. 
        OSS ossClient = new OSSClientBuilder().build(endpoint, credentialsProvider);

        try {
            // Query objects that meet the specified conditions and list information about the objects based on the specified 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 the same time, and sort the objects in ascending order. 
            String query = "{\"Field\": \"Size\",\"Value\": \"1048576\",\"Operation\": \"lt\"}";
            String sort = "Size";
            String order = "asc";
            DoMetaQueryRequest doMetaQueryRequest = new DoMetaQueryRequest(bucketName, maxResults, query, sort);
            AggregationRequest aggregationRequest = new AggregationRequest();
            List<AggregationRequest> aggregations = new ArrayList<AggregationRequest>();
            // 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");
            aggregations.add(aggregationRequest);

            // 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()){
                    System.out.println("Filename: " + file.getFilename());
                    // Query the ETag value that is used to identify the content of the object. 
                    System.out.println("ETag: " + file.getETag());
                    // Query the access control list (ACL) of the object.
                    System.out.println("ObjectACL: " + file.getObjectACL());
                    // Query the type of the object. 
                    System.out.println("OssObjectType: " + file.getOssObjectType());
                    // Query the storage class of the object. 
                    System.out.println("OssStorageClass: " + file.getOssStorageClass());
                    // Query the number of tags attached to the object. 
                    System.out.println("TaggingCount: " + file.getOssTaggingCount());
                    if(file.getOssTaggings() != null){
                        for(Tag tag : file.getOssTaggings()){
                            System.out.println("Key: " + tag.getKey());
                            System.out.println("Value: " + tag.getValue());
                        }
                    }
                    if(file.getOssUserMetas() != null){
                        for(UserMeta meta : file.getOssUserMetas()){
                            System.out.println("Key: " + meta.getKey());
                            System.out.println("Value: " + meta.getValue());
                        }
                    }
                }
            } else if(doMetaQueryResult.getAggregations() != null){
                for(Aggregation aggre : doMetaQueryResult.getAggregations()){
                    // 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 result of the aggregate operation. 
                    System.out.println("Value: " + aggre.getValue());
                    if(aggre.getGroups() != null && aggre.getGroups().size() > 0){
                        // Query the result of grouping and aggregation. 
                        System.out.println("Groups value: " + aggre.getGroups().get(0).getValue());
                        // Query the total count of grouping and aggregation. 
                        System.out.println("Groups count: " + aggre.getGroups().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.ProviderAuth(EnvironmentVariableCredentialsProvider())

# In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint. 
# Specify the name of the bucket. Example: examplebucket. 
bucket = oss2.Bucket(auth, 'http://oss-cn-hangzhou.aliyuncs.com', 'examplebucket')

# Query objects that meet specified conditions and list the object information based on the specified 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)
# Print the 64-bit CRC value of the object. 
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"
    "github.com/aliyun/aliyun-oss-go-sdk/oss"
    "os"
)
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. 
    client, err := oss.New("yourEndpoint", "", "", oss.SetCredentialsProvider(&provider))
    if err != nil {
        fmt.Println("Error:", err)
        os.Exit(-1)
    }
    // Query objects that meet the specified conditions and list object information based on the specified fields and sorting methods. 
    // 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",
    }
    // Specify the name of the bucket. Example: examplebucket. 
    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)
        }
    }
}