1      背景介绍

OBS 文件语义桶支持文件系统语义，提供文件修改写、rename等功能。下面代码展示OBS SDK使用文件语义桶进行修改写、追加写的功能。

2      代码展示

2.1      文件语义桶之修改写

需要先下载OBS最新的JAVA SDK，参考官网链接：https://developer.huaweicloud.cn/sdk?OBS，并在自己的项目中导入SDK中的JAR包。

前提条件：已创建文件语义桶，例如obs-bigdata00-posix

package samples_java;
import java.io.IOException;
import java.io.ByteArrayInputStream;

import com.obs.services.ObsClient;
import com.obs.services.ObsConfiguration;
import com.obs.services.exception.ObsException;
import com.obs.services.model.*;
import com.obs.services.model.fs.ObsFSFile;
import com.obs.services.model.fs.WriteFileRequest;

public class ObjectTestSample {
     private static final String endPoint = "XXX";

     private static final String ak = "XXX";

     private static final String sk = "XXX";

     private static ObsClient obsClient;

     private static String bucketName = "obs-bigdata00-posix";

     private static String objectKey = "obs-testfile";

     public static void main(String[] args)
             throws IOException {
         ObsConfiguration config = new ObsConfiguration();
         config.setSocketTimeout(30000);
         config.setConnectionTimeout(10000);
         config.setEndPoint(endPoint);
         try {
            obsClient = new ObsClient(ak, sk, config);

             String content = "Hello OBS";
             obsClient.putObject(bucketName,objectKey,new ByteArrayInputStream(content.getBytes("UTF-8")), null);
             ObjectMetadata metadata = obsClient.getObjectMetadata(bucketName,objectKey);
             WriteFileRequest request = new WriteFileRequest();
             request.setBucketName(bucketName);
             request.setObjectKey(objectKey);
             request.setInput(new ByteArrayInputStream("Hi".getBytes()));
             request.setPosition(2);
             ObsFSFile result = obsClient.writeFile(request);

         } catch (ObsException e) {
             System.out.println("Response Code: " + e.getResponseCode());
             System.out.println("Error Message: " + e.getErrorMessage());
             System.out.println("Error Code:       " + e.getErrorCode());
             System.out.println("Request ID:      " + e.getErrorRequestId());
             System.out.println("Host ID:           " + e.getErrorHostId());
         } finally {
             if (obsClient != null) {
                 try {

                     obsClient.close();
                 } catch (IOException e) {
                     System.out.println(e);
                 }
             }
         }
     }
 }

2.2      文件语义桶之追加写

需要先下载OBS最新的JAVA SDK，参考官网链接：https://developer.huaweicloud.cn/sdk?OBS，并在自己的项目中导入SDK中的JAR包。

前提条件：已创建文件语义桶，例如obs-bigdata00-posix

package samples_java;
import java.io.IOException;
import java.io.ByteArrayInputStream;

import com.obs.services.ObsClient;
import com.obs.services.ObsConfiguration;
import com.obs.services.exception.ObsException;
import com.obs.services.model.*;
import com.obs.services.model.fs.ObsFSFile;
import com.obs.services.model.fs.WriteFileRequest;

public class ObjectTestSample {
     private static final String endPoint = "XXX";

     private static final String ak = "XXX";

     private static final String sk = "XXX";

     private static ObsClient obsClient;

     private static String bucketName = "obs-bigdata00-posix";

     private static String objectKey = "obs-testfile";

     public static void main(String[] args)
             throws IOException {
         ObsConfiguration config = new ObsConfiguration();
         config.setSocketTimeout(30000);
         config.setConnectionTimeout(10000);
         config.setEndPoint(endPoint);
         try {
             obsClient = new ObsClient(ak, sk, config);

             String content = "Hello OBS";
             obsClient.putObject(bucketName,objectKey,new ByteArrayInputStream(content.getBytes("UTF-8")), null);
             ObjectMetadata metadata = obsClient.getObjectMetadata(bucketName,objectKey);
             WriteFileRequest request = new WriteFileRequest();
             request.setBucketName(bucketName);
             request.setObjectKey(objectKey);
             request.setInput(new ByteArrayInputStream("Hi Huawei".getBytes()));
             request.setPosition(metadata.getContentLength());
             ObsFSFile result = obsClient.appendFile(request);

         } catch (ObsException e) {
             System.out.println("Response Code: " + e.getResponseCode());
             System.out.println("Error Message: " + e.getErrorMessage());
             System.out.println("Error Code:       " + e.getErrorCode());
             System.out.println("Request ID:      " + e.getErrorRequestId());
             System.out.println("Host ID:           " + e.getErrorHostId());
         } finally {
             if (obsClient != null) {
                 try {
                     obsClient.close();
                 } catch (IOException e) {
                     System.out.println(e);
                 }
             }
         }
     }
 }

3      效果展示

3.1      文件语义桶之修改写

第一步：上传文件obs-testfile，内容为Hello OBS

第二步：修改写文件obs-testfile，从Position(2)开始，修改内容为Hi，修改后文件obs-testfile，内容为HeHio OBS

3.2      文件语义桶之追加写

第一步：上传文件obs-testfile，内容为Hello OBS

第二步：追加写文件obs-testfile后，文件内容为Hello OBSHi Huawei