View the object in the bucket

Updated at：2025-11-03

Simple query

View the list of objects in a bucket.

Basic workflow

Instantiate the BOSClient class.
Calling the BOSClient.listObjects(bucketName) method returns an instance of the ListObjectsResponse class.
For the ListObjectsResponse class, methods like getBuckets(), getOwner(), and getMetadata() can be executed.

Example code

                Java
                
            

                // Obtain all object information under the specified bucket
ListObjectsResponse listing = client.listObjects(<BucketName>);
 // Traverse all objects
for (BosObjectSummary objectSummary : listing.getContents()) {
    System.out.println("ObjectKey: " + objectSummary.getKey());
}
            

Note: The listObjects() method returns a ListObjectsResponse object, which contains the results of this listObject request. Users can obtain the description information of all objects through the getContents method in ListObjectsResponse.

By default, if the number of objects in the bucket exceeds 1,000, only 1,000 objects will be returned. In this case, the IsTruncated value in the returned result will be set to True, and NextMarker will be provided as the starting point for the next retrieval.

To retrieve more objects, use the Marker parameter for reading in batches. Refer to [Extended Query](#Extended query).

Complete example

                Java
                
            

                import android.app.Activity;
import android.os.Bundle;
import com.baidubce.BceClientException;
import com.baidubce.BceServiceException;
import com.baidubce.auth.DefaultBceCredentials;
import com.baidubce.demo.R;
import com.baidubce.services.bos.BosClient;
import com.baidubce.services.bos.BosClientConfiguration;
import com.baidubce.services.bos.model.BosObjectSummary;
import com.baidubce.services.bos.model.ListObjectsResponse;
public class ExampleActivity extends Activity {
private String bucketName = <BucketName>;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    new Thread(new Runnable() {
        @Override
        public void run() {
            try {
                BosClientConfiguration config = new BosClientConfiguration();
                config.setCredentials(new DefaultBceCredentials(<AccessKeyId>, <SecretAccessKey>));
                config.setEndpoint(<EndPoint>);
                BosClient client = new BosClient(config);
 // Obtain all object information under the specified bucket
                ListObjectsResponse listing = client.listObjects(<BucketName>);
 // Traverse all objects
                for (BosObjectSummary objectSummary : listing.getContents()) {
                    System.out.println("ObjectKey: " + objectSummary.getKey());
                }               	                    
            } catch (BceServiceException e) {
                System.out.println("Error ErrorCode: " + e.getErrorCode());
                System.out.println("Error RequestId: " + e.getRequestId());
                System.out.println("Error StatusCode: " + e.getStatusCode());
                System.out.println("Error Message: " + e.getMessage());
                System.out.println("Error ErrorType: " + e.getErrorType());
            } catch (BceClientException e) {
                System.out.println("Error Message: " + e.getMessage());
            }
        }
    }).start();
}}
            

Extended query

Users can configure the ListObjectsRequest parameters to perform advanced query operations. The extended parameters available for configuration in ListObjectsRequest include the following:

Parameter name	Description	Default value
MaxKeys	Specify the maximum number of objects to return, which must not exceed 1,000.	1000
Prefix	Set the prefix of the objectKey. The prefix means that the objectKey contains and starts with the value of Prefix. It is usually used in conjunction with Delimiter when [querying simulated folders](#Query simulated folders).	-
Delimiter	It is a delimiter used to hierarchize objectKey. It is usually used in conjunction with Prefix when [querying simulated folders](#Query simulated folders). The objectKey from the Prefix to the first occurrence of the Delimiter character is called: CommonPrefixes.	-
Marker	It is a string used to set the starting position of the returned results. After setting the Marker value, the returned objects will be returned starting from the Marker value in alphabetical order.	-

Basic workflow

Create an instance of the ListObjectsRequest class.
Use methods like setDelimiter(), setMarker(), or setPrefix() in ListObjectsRequest to enable more advanced query functionalities.
Create an instance of the BOSClient class and invoke the listObjects(listObjectsRequest) method.

Example code

                Java
                
            

                // Construct a ListObjectsRequest request
ListObjectsRequest listObjectsRequest = new ListObjectsRequest(<BucketName>);  
 // Set extended query parameters
listObjectsRequest.setDelimiter(<Delimiter>);
listObjectsRequest.setMarker(<Marker>);
...   
ListObjectsResponse listing = client.listObjects(listObjectsRequest);
            

Note: The above code calls an overloaded method from listObjects by passing a ListObjectsRequest to complete the request.

Complete example

Example 1:

                Java
                
            

                import android.app.Activity;
import android.os.Bundle;
import com.baidubce.BceClientException;
import com.baidubce.BceServiceException;
import com.baidubce.auth.DefaultBceCredentials;
import com.baidubce.demo.R;
import com.baidubce.services.bos.BosClient;
import com.baidubce.services.bos.BosClientConfiguration;
import com.baidubce.services.bos.model.BosObjectSummary;
import com.baidubce.services.bos.model.ListObjectsRequest;
import com.baidubce.services.bos.model.ListObjectsResponse;
public class ExampleActivity extends Activity {
private String bucketName = <BucketName>;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    new Thread(new Runnable() {
        @Override
        public void run() {
            try {
                BosClientConfiguration config = new BosClientConfiguration();
                config.setCredentials(new DefaultBceCredentials(<AccessKeyID>, <SecretAccessKey>));
                config.setEndpoint(<EndPoint>);
                BosClient client = new BosClient(config);
 // Construct a ListObjectsRequest request
                ListObjectsRequest listObjectsRequest = new ListObjectsRequest(<BucketName>);
 // Set parameters
                listObjectsRequest.setDelimiter("/");
                listObjectsRequest.setMarker("123");
                listObjectsRequest.setMaxKeys(100);
                listObjectsRequest.setPrefix("fun");
 // Obtain all eligible object information under the specified bucket
                ListObjectsResponse listing = client.listObjects(listObjectsRequest);
 // Traverse all objects
                for (BosObjectSummary objectSummary : listing.getContents()) {
                    System.out.println("ObjectKey: " + objectSummary.getKey());
                }                	
            } catch (BceServiceException e) {
                System.out.println("Error ErrorCode: " + e.getErrorCode());
                System.out.println("Error RequestId: " + e.getRequestId());
                System.out.println("Error StatusCode: " + e.getStatusCode());
                System.out.println("Error Message: " + e.getMessage());
                System.out.println("Error ErrorType: " + e.getErrorType());
            } catch (BceClientException e) {
                System.out.println("Error Message: " + e.getMessage());
            }
        }
    }).start();
}}
            

Example II: A complete example using the NextMarker.

                Java
                
            

                import android.app.Activity;
import android.os.Bundle;
import com.baidubce.BceClientException;
import com.baidubce.BceServiceException;
import com.baidubce.auth.DefaultBceCredentials;
import com.baidubce.demo.R;
import com.baidubce.services.bos.BosClient;
import com.baidubce.services.bos.BosClientConfiguration;
import com.baidubce.services.bos.model.BosObjectSummary;
import com.baidubce.services.bos.model.ListObjectsRequest;
import com.baidubce.services.bos.model.ListObjectsResponse;
public class ExampleActivity extends Activity {
private String bucketName = <BucketName>;
@Override
protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  new Thread(new Runnable() {
      @Override
      public void run() {
         try {
            BosClientConfiguration config = new BosClientConfiguration();
            config.setCredentials(new DefaultBceCredentials(<AccessKeyId>, <SecretAccessKey>);
            config.setEndpoint(<EndPoint>);
            BosClient client = new BosClient(config);
            ListObjectsRequest listObjectsRequest = new ListObjectsRequest(<BucketName>);
            listObjectsRequest.setMarker("");
            listObjectsRequest.setMaxKeys(20);
            listObjectsRequest.setDelimiter(BceConfig.BOS_DELIMITER);
            ListObjectsResponse listObjectsResponse = client.listObjects(listObjectsRequest);
            String nextMark = "";
            if(listObjectsResponse.isTruncated()){
               nextMark = listObjectsResponse.getNextMarker();
            }
           ListObjectsRequest listObjectsRequest2 = new ListObjectsRequest(<BucketName>);
           listObjectsRequest2.setMarker(nextMark);
           listObjectsRequest2.setMaxKeys(20);
           listObjectsRequest2.setDelimiter(BceConfig.BOS_DELIMITER);
           ListObjectsResponse listing = client.listObjects(listObjectsRequest2);
           for (BosObjectSummary objectSummary : listing.getContents()) {
               System.out.println("ObjectKey: " + objectSummary.getKey());
            }                
          } catch (BceServiceException e) {
            System.out.println("Error ErrorCode: " + e.getErrorCode());
            System.out.println("Error RequestId: " + e.getRequestId());
            System.out.println("Error StatusCode: " + e.getStatusCode());
            System.out.println("Error Message: " + e.getMessage());
            System.out.println("Error ErrorType: " + e.getErrorType());
         } catch (BceClientException e) {
            System.out.println("Error Message: " + e.getMessage());
         }
      }
    }).start();
}}
            

Query simulated folders

Since BOS is inherently a (<Key>,<Value>) storage system, the concept of "folder" does not exist in principle. However, you can simulate the folder function by combining the Delimiter and Prefix} parameters.

Suppose the bucket contains five files: bos.jpg, fun/, fun/test.jpg, fun/movie/001.avi, and fun/movie/007.avi. The "/" symbol can be used as a delimiter to mimic folder structures.

Recursively list all files under the simulated folder

You can obtain all files under a simulated folder by setting the Prefix parameter:

                Java
                
            

                // Construct a ListObjectsRequest request
ListObjectsRequest listObjectsRequest = new ListObjectsRequest(<BucketName>);
 // Recursively list all files under the fun directory
listObjectsRequest.setPrefix("fun/");
ListObjectsResponse listing = client.listObjects(listObjectsRequest);
 // Traverse all objects
System.out.println("Objects:");
for (BosObjectSummary objectSummary : listing.getContents()) {
   System.out.println(objectSummary.getKey());
}
            

Output:

                Java
                
            

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

View files and subfolders under the simulated folder

With the combination of Prefix and Delimiter, it can list files and subfolders under the simulated folder:

                Java
                
            

                // Construct a ListObjectsRequest request
ListObjectsRequest listObjectsRequest = new ListObjectsRequest(<BucketName>);
 // Specify "/" as the delimiter for simulated folder
listObjectsRequest.setDelimiter("/");
 // List all files and subfolders under the “fun” folder
listObjectsRequest.setPrefix("fun/");
ListObjectsResponse listing = client.listObjects(listObjectsRequest);
 // Traverse all objects
System.out.println("Objects:");
for (BosObjectSummary objectSummary : listing.getContents()) {
   System.out.println(objectSummary.getKey());
}
 // Traverse all CommonPrefix
System.out.println("\nCommonPrefixs:");
for (String commonPrefix : listing.getCommonPrefixes()) {
   System.out.println(commonPrefix);
}
            

Output:

                Java
                
            

                Objects:
fun/
fun/test.jpg
CommonPrefixs:
fun/movie/
            

Description:

In the returned results, the list under Objects shows the files under the fun folder. The list in CommonPrefixs shows all subfolders under the fun folder. It can be seen that the two files fun/movie/001.avi and fun/movie/007.avi are not listed because they belong to the movie subfolder under the fun folder.

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