java socket服务器，客户端检测服务器已经死亡

Question

If I kill the Socket Server process, my Socket client process does not receive any errors, it continues to loop forever on the following code:

public void run() {
    while(readData) {
      String inputLine = null;
      try {
        while((inputLine = m_inputStream.readLine()) != null) {
          //do stuff
        }
      } catch (IOException e) {
         readData = false;
     }
  }
}

How can I detect that the socket server is gone and terminate the loop?

Answer 1

Terminate the outer loop when the call to readLine() returns null .

No exception is thrown when the server closes the connection normally. The stream should return null to signal the end of data.

This can be done with a loop like this:

public void run() {
  try {
    while (true) {
      String line = input.readLine();
      if (line == null)
        break;
      /* Process line. */
      ...
    }
  } catch (IOException ex) {
    /* Handle the exception as desired. */
    ex.printStackTrace();
  }
}

Answer 2

Whilst the answer from erickson is correct, have you tried setting the socket read time-out properties ? (eg sun.net.client.defaultReadTimeout ). If it is possible that the server may take a long time responding, then this might be less useful as a solution to your problem but is a good idea nevertheless in many scenarios.