Google Cloud Storageのドキュメント - Java API概要 その12

Google Cloud StorageのJava APIの概要についての
ドキュメントを翻訳しています。

翻訳元はこちらです。

このドキュメントは、Google App Engineアプリケーションから
Google Cloud Storageの機能を呼び出す方法について
説明しています。

現在は試験的運用中なので、今後変更があるかもしれません。

第1回はこちら、第2回はこちら、第3回はこちら、
第4回はこちら、第5回はこちら、第6回はこちら、
第7回はこちら、第８回はこちら、第9回はこちら、
第10回はこちら、第11回はこちらです。

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• 以下のコードでGuestbookServlet.javaのdoGet()メソッドを上書きして、BACKETNAMEとFILENAMEをあなたのバケット及びファイル名に書き換えます。

  /**
   * Copyright 2011 Google Inc. All Rights Reserved.
   * Create, Write, Read, and Finalize Cloud Storage objects.
   * Access your app at: http://myapp.appspot.com/
  **/
  
  @SuppressWarnings("serial")
  /**
   * Copyright 2011 Google Inc. All Rights Reserved.
   * Create, Write, Read, and Finalize Cloud Storage objects.
   * Access your app at: http://myapp.appspot.com/
  **/
  
  @SuppressWarnings("serial")
  public class GuestbookServlet extends HttpServlet {
     public static final String BUCKETNAME = "YOUR_BUCKET_NAME";
     public static final String FILENAME = "YOUR_FILE_NAME";
  
    @Override
    public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
      resp.setContentType("text/plain");
      resp.getWriter().println("Hello, world from java");
      FileService fileService = FileServiceFactory.getFileService();
      GSFileOptionsBuilder optionsBuilder = new GSFileOptionsBuilder()
         .setBucket(BUCKETNAME)
         .setKey(FILENAME)
         .setMimeType("text/html")
         .setAcl("public_read")
         .addUserMetadata("myfield1", "my field value");
      AppEngineFile writableFile =
           fileService.createNewGSFile(optionsBuilder.build());
      // Open a channel to write to it
       boolean lock = false;
       FileWriteChannel writeChannel =
           fileService.openWriteChannel(writableFile, lock);
       // Different standard Java ways of writing to the channel
       // are possible. Here we use a PrintWriter:
       PrintWriter out = new PrintWriter(Channels.newWriter(writeChannel, "UTF8"));
       out.println("The woods are lovely dark and deep.");
       out.println("But I have promises to keep.");
       // Close without finalizing and save the file path for writing later
       out.close();
       String path = writableFile.getFullPath();
       // Write more to the file in a separate request:
       writableFile = new AppEngineFile(path);
       // Lock the file because we intend to finalize it and
       // no one else should be able to edit it
       lock = true;
       writeChannel = fileService.openWriteChannel(writableFile, lock);
       // This time we write to the channel directly
       writeChannel.write(ByteBuffer.wrap
                 ("And miles to go before I sleep.".getBytes()));
  
       // Now finalize
       writeChannel.closeFinally();
       resp.getWriter().println("Done writing...");
  
       // At this point, the file is visible in App Engine as:
       // "/gs/BUCKETNAME/FILENAME"
       // and to anybody on the Internet through Cloud Storage as:
       // (http://storage.googleapis.com/BUCKETNAME/FILENAME)
       // We can now read the file through the API:
       String filename = "/gs/" + BUCKETNAME + "/" + FILENAME;
       AppEngineFile readableFile = new AppEngineFile(filename);
       FileReadChannel readChannel =
           fileService.openReadChannel(readableFile, false);
       // Again, different standard Java ways of reading from the channel.
       BufferedReader reader =
               new BufferedReader(Channels.newReader(readChannel, "UTF8"));
       String line = reader.readLine();
       resp.getWriter().println("READ:" + line);
  
      // line = "The woods are lovely, dark, and deep."
       readChannel.close();
    }
  }
  

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