Object管理

上传Object

最简单的上传

• 基本流程

  1. 创建BOSClient 类的实例。
  2. 调用BOSClient.putObject()方法，可以通过如下四种方式上传Object：文件、数据流、二进制串和字符串的形式。
  3. 对返回的PutObjectResponse类型实例，执行getETag()获得上传成功的ETag。

• 示例代码

  // 获取指定文件
  File file = new File(<FilePath>);     //指定文件路径
  
  // 以文件形式上传Object
  PutObjectResponse putObjectFromFileResponse = 
      client.putObject(<BucketName>, <ObjectKey>, file);
  
  // 获取数据流
  InputStream inputStream = new FileInputStream(<FilePath>);
  
  // 以数据流形式上传Object
  PutObjectResponse putObjectResponseFromInputStream = 
      client.putObject(<BucketName>, <ObjectKey>, inputStream);
  
  // 以二进制串上传Object
  PutObjectResponse putObjectResponseFromByte = 
      client.putObject(<BucketName>, <ObjectKey>, <byte>);
  
  // 以字符串上传Object
  PutObjectResponse putObjectResponseFromString = 
      client.putObject(<BucketName>, <ObjectKey>, <string>);
  
  // 打印ETag
  System.out.println(putObjectFromFileResponse.getETag());

  说明：Object以文件的形式上传到BOS中，putObject函数支持不超过5GB的Object上传。在putObject请求处理成功后，BOS会在Header中返回Object的ETag作为文件标识。

• 完整示例

  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.InputStream;
  import android.app.Activity;
  import android.os.Bundle;
  import com.baidubce.BceClientException;
  import com.baidubce.BceServiceException;
  import com.baidubce.auth.DefaultBceCredentials;
  import com.baidubce.development.R;
  import com.baidubce.services.bos.BosClient;
  import com.baidubce.services.bos.BosClientConfiguration;
  import com.baidubce.services.bos.model.PutObjectResponse;
  ​    
  public class ExampleActivity extends Activity {
  
    private String bucketName = <BucketName>;
    private String objectKey = <ObjectKey>;
    byte[] b = null;
    String str = <PutString>;
  
    @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);
  
                  // 获取指定文件
                  File file = new File("/path/to/file.zip");
  
                  // 以文件形式上传Object
                  PutObjectResponse putObjectFromFileResponse = client.putObject(<BucketName>, <ObjectKey>, file);
  
                  // 获取数据流
                  InputStream inputStream = new FileInputStream("/path/to/test.zip");
  
                  // 以数据流形式上传Object
                  PutObjectResponse putObjectResponseFromInputStream = client.putObject(<BucketName>, <ObjectKey>, inputStream);
  
                  // 以二进制串上传Object
                  PutObjectResponse putObjectResponseFromByte = client.putObject(<BucketName>, <ObjectKey>, b);
  
                  // 以字符串上传Object
                  PutObjectResponse putObjectResponseFromString = client.putObject(<BucketName>, <ObjectKey>, str);
  
                  // 打印ETag
                  System.out.println(putObjectFromFileResponse.getETag());
  
              } 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());
              } catch (FileNotFoundException e) {
                  // TODO Auto-generated catch block
                  e.printStackTrace();
              } 
          }
      }).start();
  }}

设定Object的Copy属性

CopyObject接口用于将一个已经存在的Object拷贝到另外一个Object，拷贝过程中会对源Object的Etag或修改状态进行判断，根据判断结果决定是否执行拷贝。详细的参数解释如下：

• 示例代码

  // 初始化BosClient
  BosClient client = ...;
  
  // 创建CopyObjectRequest对象
  CopyObjectRequest copyObjectRequest = new CopyObjectRequest(srcBucketName, srcKey, destBucketName, destKey);
  
  // 设置新的Metadata
  Map<String, String> userMetadata = new HashMap<String, String>();
  userMetadata.put("<user-meta-key>","<user-meta-value>");
  ObjectMetadata meta = new ObjectMetadata();
  meta.setUserMetadata(userMetadata);
  copyObjectRequest.setNewObjectMetadata(meta);
  
  //copy-source-if-match
  copyObjectRequest.withETag("111111111183bf192b57a4afc76fa632");
  //copy-source-if-none-match
  copyObjectRequest.withNoMatchingETagConstraint("111111111183bf192b57a4afc76fa632");
  
  Date modifiedSinceConstraint = new Date();    
  SimpleDateFormat df = new SimpleDateFormat("E, dd MMM yyyy HH:mm:ss z", Locale.UK);  
  df.setTimeZone(new java.util.SimpleTimeZone(0, "GMT"));        
  String date = df.format(modifiedSinceConstraint);
  
  //copy-source-if-modified-since
  copyObjectRequest.withModifiedSinceConstraint(date);
  
  //copy-source-if-unmodified-since
  copyObjectRequest.withUnmodifiedSinceConstraint(date);
  
  // 复制Object
  CopyObjectResponse copyObjectResponse = client.copyObject(copyObjectRequest);

设定Object的Http Header

BOS支持您在上传object时设定Http Header。

• 基本流程

  1. 创建ObjectMetadata类的实例。
  2. 执行setContentLength()/setContentType()等方法对Http Header进行设定。
  3. 将设定后的meta作为参数加入client.putObject()中。

• 示例代码

  // 创建ObjectMetadata类的实例
  ObjectMetadata meta = new ObjectMetadata();
  
  // 设置ContentLength大小
  meta.setContentLength(<Length>);
  
  // 设置ContentType
  meta.setContentType("application/json");
  
  client.putObject(<BucketName>, <ObjectKey>, content, meta);

  说明：header可设置的属性有："Cache-Control"、"Content-Encoding"、"Content-Disposition"、"Expires"

• 完整示例

  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.InputStream;
  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.ObjectMetadata;
  import com.baidubce.services.bos.model.PutObjectResponse;
  
  public class ExampleActivity extends Activity {
  
  private String bucketName = <BucketName>;
  private String objectKey = <ObjectKey>;
  
  @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);
  
                  // 获取数据流
                  InputStream inputStream = new FileInputStream("/path/to/test.zip");
  
                  // 创建ObjectMetadata类的实例
                  ObjectMetadata meta = new ObjectMetadata();
  
                  // 设置ContentLength大小
                  meta.setContentLength(1000);
  
                  // 设置ContentType
                  meta.setContentType("application/json");
  
                  PutObjectResponse putObjectResponseFromInputStream = client.putObject(bucketName, objectKey, inputStream, meta);
  
                   // 打印ETag
                  System.out.println(putObjectResponseFromInputStream.getETag());
  
              } 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());
              } catch (FileNotFoundException e) {
                  // TODO Auto-generated catch block
                  e.printStackTrace();
              } 
          }
      }).start();
  }}

用户自定义元数据

BOS支持用户自定义元数据来对Object进行描述。

• 基本流程

  1. 创建ObjectMetadata类的实例。
  2. 执行addUserMetadata()方法对Http Header进行自定义元数据。
  3. 将设定后的meta作为参数加入client.putObject()中。

• 示例代码

  // 设置自定义元数据name的值为my-data
  meta.addUserMetadata("name", "my-data");	  
  
  // 上传Object
  client.putObject(<BucketName>, <ObjectKey>, <Content>, meta);

  说明：在上面代码中，用户自定义了一个名字为”name”，值为”my-data”的元数据。当用户下载此Object的时候，此元数据也可以一并得到。一个Object可以有多个类似的参数，但所有的User Meta总大小不能超过2KB。

• 完整示例

  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.InputStream;
  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.ObjectMetadata;
  import com.baidubce.services.bos.model.PutObjectResponse;
  
  public class ExampleActivity extends Activity {
  
  private String bucketName = <BucketName>;
  private String objectKey = <ObjectKey>;
  
  @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);
  
                  // 获取数据流
                  InputStream inputStream = new FileInputStream("/path/to/test.zip");
  
                  // 创建ObjectMetadata类的实例
                  ObjectMetadata meta = new ObjectMetadata();
  
                  // 自定义元数据
                  meta.addUserMetadata("name", "my-data");	    
  
                  PutObjectResponse putObjectResponseFromInputStream = client.putObject(<BucketName>, <ObjectKey>, inputStream, meta);
  
                   // 打印ETag
                  System.out.println(putObjectResponseFromInputStream.getETag());
  
              } 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());
              } catch (FileNotFoundException e) {
                  // TODO Auto-generated catch block
                  e.printStackTrace();
              } 
          }
      }).start();
  }}

Append方式上传Object

BOS支持AppendObject，即以追加写的方式上传文件，适用场景如日志追加及直播等实时视频文件上传。通过AppendObject操作创建的Object类型为Appendable Object，可以对该Object追加数据；而通过PutObject上传的Object是Normal Object，不可进行数据追加写。AppendObject大小限制为0~5G。

• 示例代码

  public void AppendObject(BosClient client, String bucketName, String objectKey, byte[] byte1, String string1) {
        // 获取指定文件
        File file = new File("/path/to/file.zip");
        // 获取数据流
        InputStream inputStream = new FileInputStream("/path/to/test.zip");
  
        // 以文件形式上传Object
        AppendObjectResponse appendObjectFromFileResponse = client.appendObject(bucketName, objectKey, file);
        // 以数据流形式上传Object
        AppendObjectResponse appendObjectResponseFromInputStream = client.appendObject(bucketName, objectKey, inputStream);
        // 以二进制串上传Object
        AppendObjectResponse appendObjectResponseFromByte = client.appendObject(bucketName, objectKey, byte1);
        // 以字符串上传Object
        AppendObjectResponse appendObjectResponseFromString = client.appendObject(bucketName, objectKey, string1);
  
        // 向AppendFile追加内容
        Long nextOffset = appendObjectFromFileResponse.getNextAppendOffset();
        AppendObjectRequest request =new AppendObjectRequest(bucketName, objectKey,
        RestartableInputStream.wrap(string1.getBytes()));
        request.withOffset(nextOffset);
        AppendObjectResponse appendResponse = client.appendObject(request);      
  }

  ​

获取上传进度

Android SDK支持在上传过程中实时提供上传进度信息。目前支持PutObject, AppendObject, UploadPart以及PutSuperObjectFromFile四个接口。进度上传接口的使用必须构造对应的Request (PutObjectRequest, AppendObjectRequest, UploadPartRequest以及PutSuperObjectRequest)。

SDK提供的上传进度回调接口如下，您可以在其中定义上传过程中您所需要的操作，如更新界面等等。

public interface BceProgressCallback<T extends AbstractBceRequest> {
      // request为上传的请求
      // currentSize为当前上传的大小(单位:byte)
      // totalSize为本次请求需要上传的总大小(单位:byte)
      void onProgress(T request, long currentSize, long totalSize);
｝

• PutObject示例代码：

  PutObjectRequest request = new PutObjectRequest(this.bucketName, "test", file);
  ObjectMetadata objectMetadata = new ObjectMetadata();
  objectMetadata.setContentType("text/plain");
  request.setObjectMetadata(objectMetadata);
  request.setProgressCallback(new BosProgressCallback<PutObjectRequest>() {
      @Override
      public void onProgress(PutObjectRequest request, long currentSize, long totalSize) {
          Log.e(currentSize + "", totalSize + "");
      }
  });
  String eTag = this.client.putObject(request).getETag();

• AppendObject示例代码：

  ObjectMetadata objectMetadata = new ObjectMetadata();
  objectMetadata.setContentType("text/plain");
  AppendObjectRequest request = new AppendObjectRequest(this.bucketName, "test", file);
  request.setObjectMetadata(objectMetadata);
  AppendObjectResponse response = this.client.appendObject(request);
  Long nextOffset = response.getNextAppendOffset();
  request.withOffset(nextOffset);
  request.setProgressCallback(new BosProgressCallback<AppendObjectRequest>() {
      @Override
      public void onProgress(AppendObjectRequest request, long currentSize, long totalSize) {
          Log.e(currentSize + "", totalSize + "");
      }
  });
  response = this.client.appendObject(request);

• UploadPart示例代码：

  UploadPartRequest request = new UploadPartRequest().withBucketName(this.bucketName)
          .withKey("test").withUploadId(uploadId).withPartNumber(1).withPartSize(8000)
          .withInputStream(fis);
  request.setProgressCallback(new BosProgressCallback<UploadPartRequest>() {
      @Override
      public void onProgress(UploadPartRequest request, long currentSize, long totalSize) {
          Log.e(currentSize + "", totalSize + "");
      }
  });
  UploadPartResponse response = this.client.uploadPart(request);

• PutSuperObjectFromFile示例代码：

  PutSuperObjectRequest request = new PutSuperObjectRequest().withBucketName(this.bucketName)
          .withKey("test").withPartSize(1024*1024*2L).withFile(file);
  request.setProgressCallback(new BosProgressCallback<PutSuperObjectRequest>() {
      @Override
      public void onProgress(PutSuperObjectRequest request, long currentSize, long totalSize) {
          Log.e(currentSize + "", totalSize + "");
      }
  });
  PutSuperObjectResponse response = this.client.putSuperObjectFromFile(request);

  目前，SDK默认上传进度的回调粒度为2048个字节。您可以通过如下方法设置一个更适合您App应用的回调粒度：

  BosClientConfiguration config=new BosClientConfiguration(); config.setUploadSegmentPart(1024);

注意： 该值必须在1-8192之间，如不在该范围内，Android SDK会强制设置为2048.

取消接口

Android SDK支持在请求过程中取消本次请求，其中上传请求中剩余的数据将不再会上传至BOS，下载请求中取消操作会关闭连接，执行中的操作会抛出Request is canceled!异常

所有的BOS操作都可以使用取消接口，但是已经完成的请求无法被取消，已经完成的操作也不会抛出异常

// 以上传接口取消为例
final PutObjectRequest req = new PutObjectRequest(<BucketName>, <ObjectName>,
         new FileInputStream(<FilePath>));
Runnable cancelTask = new Runnable() {
    @Override
    public void run() {
        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
            e.printStackTrace()
        }
        // 取消本次上传请求
        req.cancel();
    }
};
new Thread(cancelTask).start();
client.putObject(req);

同步回调

Android SDK支持BOS服务端同步回调接口，通过在PutObjectRequest中，设置process参数，就可以在上传完成后，让BOS服务端主动调用回调接口来达到通知客户目的。

PutObjectRequest request = new PutObjectRequest({bucket}, {object}, {inputStream});
// 设置x-bce-process参数
request.setProcess({x-bce-process});
PutObjectResponse response = client.putObject(request);
// 获取返回的http status code
int statusCode = response.getHttpResponse().getStatusCode();
// 获取返回的回调接口返回的数据
string callbackString = response.getServerCallbackReturnBody();

查看Bucket中的Object

简单查询

查看Bucket中Object列表。

• 基本流程

  1. 创建BOSClient类的实例。
  2. 执行BOSClient.listObjects(bucketName)方法，会返回ListObjectsResponse类的实例。
  3. 对ListObjectsResponse类型可以进行getBuckets()/getOwner()/getMetadata()操作。

• 示例代码

  // 获取指定Bucket下的所有Object信息
  ListObjectsResponse listing = client.listObjects(<BucketName>);
  
  // 遍历所有Object
  for (BosObjectSummary objectSummary : listing.getContents()) {
      System.out.println("ObjectKey: " + objectSummary.getKey());
  }

  说明： listObjects( )方法返回ListObjectsResponse对象，ListObjectsResponse对象包含了此次listObject请求的返回结果。用户可以通过ListObjectsResponse中的getContents方法获取所有Object的描述信息。

  • 默认情况下，如果Bucket中的Object数量大于1000，则只会返回1000个Object，并且返回结果中IsTruncated值为True，并返回NextMarker做为下次读取的起点。
  • 若想获取更多的Object，可以使用Marker参数分次读取，请参考扩展查询。

• 完整示例

  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);
  
                  // 获取指定Bucket下的所有Object信息
                  ListObjectsResponse listing = client.listObjects(<BucketName>);
  
                  // 遍历所有Object
                  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();
  }}

扩展查询

用户可以通过设置ListObjectsRequest参数来完成更多扩展查询操作设置。ListObjectsRequest中可以设置的扩展参数如下：

• 基本流程

  1. 创建ListObjectsRequest类的实例。
  2. 在ListObjectsRequest中执行setDelimiter/setMarker()/setPrefix()等方法，实现更多的扩展查询操作。
  3. 创建BOSClient类的实例，执行listObjects(listObjectsRequest)。

• 示例代码

  // 构造ListObjectsRequest请求
  ListObjectsRequest listObjectsRequest = new ListObjectsRequest(<BucketName>);  
  
  // 设置扩展查询参数
  listObjectsRequest.setDelimiter(<Delimiter>);
  listObjectsRequest.setMarker(<Marker>);
  ...   
  ListObjectsResponse listing = client.listObjects(listObjectsRequest);

  说明：上面代码中调用了 listObjects 中的一个重载方法，通过传入 ListObjectsRequest 来完成请求。

• 完整示例

  示例一：

  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);
  
                  // 构造ListObjectsRequest请求
                  ListObjectsRequest listObjectsRequest = new ListObjectsRequest(<BucketName>); 
  
                  // 设置参数
                  listObjectsRequest.setDelimiter("/");
                  listObjectsRequest.setMarker("123");
                  listObjectsRequest.setMaxKeys(100);
                  listObjectsRequest.setPrefix("fun");
  
                  // 获取指定Bucket下符合上述条件的所有Object信息
                  ListObjectsResponse listing = client.listObjects(listObjectsRequest);
  
                  // 遍历所有Object
                  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();
  }}

  示例二：使用Nextmarker完整示例。

  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();
  }}