如何使用java以編程方式在Amazon S3存儲桶之間傳輸文件？

Question

我是亞馬遜s3 web服務中的新成員，需要開發一個命令行應用程序來在Amazon S3存儲桶之間傳輸文件。輸入文件的內容必須轉換爲目標格式，然後複製到目標文件夾。目標格式可以是XML或Json，文件內容可以遵循給定的數據模型。

我對Java有中介經驗，並且剛剛創建了一個尚未解決的帳戶，因此試圖開發一個工作流程來解決問題。

Answer 1

好吧，這並不難。幾個月前，我已經給客戶做過了，您可能會在下面找到代碼。要從AmazonS3存儲桶讀取文件，請閱讀本Amazon文檔[1]。要將文件寫入Amazon s3存儲桶，請閱讀本文檔[2]。

除此之外，您可能需要將所有訪問令牌添加到本地操作系統。你可以從管理員那裏得到一些幫助。正如我記得的，獲得正確的憑證是唯一棘手的部分。

亞馬遜有一個很好的小文件，我建議你也要經歷一下。

package org.saig.watermark.demo; 

import java.io.File; 
import java.io.FileNotFoundException; 
import java.io.FileOutputStream; 
import java.io.FilterInputStream; 
import java.io.IOException; 
import java.net.URL; 

import org.apache.commons.io.IOUtils; 
import org.apache.commons.logging.Log; 
import org.apache.commons.logging.LogFactory; 

import com.amazonaws.AmazonClientException; 
import com.amazonaws.HttpMethod; 
import com.amazonaws.auth.AWSCredentials; 
import com.amazonaws.auth.profile.ProfileCredentialsProvider; 
import com.amazonaws.regions.Region; 
import com.amazonaws.regions.Regions; 
import com.amazonaws.services.s3.AmazonS3; 
import com.amazonaws.services.s3.AmazonS3Client; 
import com.amazonaws.services.s3.model.GeneratePresignedUrlRequest; 
import com.amazonaws.services.s3.model.GetObjectRequest; 
import com.amazonaws.services.s3.model.PutObjectRequest; 
import com.amazonaws.services.s3.model.S3Object; 

public class AmazonS3Util { 
    private static AWSCredentials credentials = null; 
    private static final String fileSeparator = "/"; 
    private static final Log log = LogFactory.getLog(AmazonS3Util.class); 
    static { 
     /* 
     * The ProfileCredentialsProvider will return your [default] 
     * credential profile by reading from the credentials file located at 
     * (~/.aws/credentials). 
     */ 
     try { 
      credentials = new ProfileCredentialsProvider().getCredentials(); 
     } catch (Exception e) { 
      throw new AmazonClientException(
              "Cannot load the credentials from the credential profiles file. " 
                + "Please make sure that your credentials file is at the correct " 
                + "location (~/.aws/credentials), and is in valid format.", 
              e); 
     } 
    } 

    public static void readFileFromS3cketBucket(String bucketName, String key, String dirPath, 
               String fileName) { 
     FilterInputStream inputStream = null; 
     FileOutputStream outputStream = null; 
     try { 
      // Remove the file if it already exists. 
      if (new File(dirPath + WatermarkConstants.fileSeparator + fileName).exists()) { 
       FileUtil.delete(new File(dirPath + WatermarkConstants.fileSeparator + fileName)); 
      } 

      AmazonS3 s3 = new AmazonS3Client(credentials); 
      Region usEast1 = Region.getRegion(Regions.US_EAST_1); 
      s3.setRegion(usEast1); 
      log.info("Downloading an object from the S3 bucket."); 
      S3Object object = s3.getObject(new GetObjectRequest(bucketName, key)); 
      log.info("Content-Type: " + object.getObjectMetadata().getContentType()); 
      inputStream = object.getObjectContent(); 

      File dirForOrder = new File(dirPath); 
      if (!dirForOrder.exists()) { 
       dirForOrder.mkdir(); 
      } 

      outputStream = new FileOutputStream(new File(dirPath + fileSeparator + fileName)); 
      IOUtils.copy(inputStream, outputStream); 
      inputStream.close(); 
      outputStream.close(); 
     } catch (FileNotFoundException e) { 
      log.error(e); 
     } catch (IOException e) { 
      log.error(e); 
     } 
    } 

    public static void uploadFileToS3Bucket(String bucketName, String key, String dirPath, 
              String fileName) { 
     AmazonS3 s3 = new AmazonS3Client(credentials); 
     Region usEast1 = Region.getRegion(Regions.US_EAST_1); 
     s3.setRegion(usEast1); 
     s3.putObject(new PutObjectRequest(bucketName, key, new File(dirPath + fileSeparator + 
                    fileName))); 
     try { 
      FileUtil.delete(new File(dirPath)); 
     } catch (IOException e) { 
      log.error(e); 
     } 

    } 

    public static void main(String[] args) { 
     readFileFromS3cketBucket("bucketName", 
           "s3Key", 
           "localFileSystemPath", 
           "destinationFileName.pdf"); 
    } 
} 

希望這會有所幫助。快樂編碼！

[1] http://docs.aws.amazon.com/AmazonS3/latest/dev/RetrievingObjectUsingJava.html [2] http://docs.aws.amazon.com/AmazonS3/latest/dev/UploadObjSingleOpJava.html