public class JavaCustomReceiver extends Receiver<String> {

  String host = null;
  int port = -1;

  public JavaCustomReceiver(String host_ , int port_) {
    super(StorageLevel.MEMORY_AND_DISK_2());
    host = host_;
    port = port_;
  }

  public void onStart() {
    // Start the thread that receives data over a connection
    new Thread()  {
      @Override public void run() {
        receive();
      }
    }.start();
  }

  public void onStop() {
    // There is nothing much to do as the thread calling receive()
    // is designed to stop by itself if isStopped() returns false
  }

  /** Create a socket connection and receive data until receiver is stopped */
  private void receive() {
    Socket socket = null;
    String userInput = null;

    try {
      // connect to the server
      socket = new Socket(host, port);

      BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));

      // Until stopped or connection broken continue reading
      while (!isStopped() && (userInput = reader.readLine()) != null) {
        System.out.println("Received data '" + userInput + "'");
        store(userInput);
      }
      reader.close();
      socket.close();

      // Restart in an attempt to connect again when server is active again
      restart("Trying to connect again");
    } catch(ConnectException ce) {
      // restart if could not connect to server
      restart("Could not connect", ce);
    } catch(Throwable t) {
      // restart if there is any other error
      restart("Error receiving data", t);
    }
  }
}
 

// Assuming ssc is the JavaStreamingContext
JavaDStream<String> customReceiverStream = ssc.receiverStream(new JavaCustomReceiver(host, port));
JavaDStream<String> words = lines.flatMap(new FlatMapFunction<String, String>() { ... });
...
 

• 系統考慮到將資料轉化為適當大小的塊；
• 系統考慮到控制接收速率，如果速率限制已指定；
• 不可靠接收器比可靠接收器更加容易實現；