Question

This is my run method, it opens a socket, and waiting for an accepted connection, if connection is accepted, will have a separate Thread open for execute it:

while (isKeepRun) {

    socket = serverSocket.accept();

    WorkTask worktask = new WorkTask();
    worktask.setSocket(socket);
    worktask.setIn(new ObjectInputStream(socket.getInputStream()));
    worktask.setOut(new ObjectOutputStream(socket.getOutputStream()));

    Thread wt = new Thread(worktask);
    wt.start();


}


if (socket != null) {
    socket.close();
}

if (serverSocket != null) {
    serverSocket.close();
}

When the user call it to stop, they call this method, to change the while loop condition. in order to break the while loop:

public void stopWorking() {
    isKeepRun = false;
}

Well, the WorkTask’s run method is very simple like that:

    try {

        do {
            objectOutputStream.flush();
            receivedObj = objectInputStream.readObject();

            if (receivedObj != null){
                System.out.println(receivedObj.toString()+"             " + receivedObj.hashCode());
            }

        } while (receivedObj != null
                && !receivedObj.equals(SharedConstant.SOCKET_EOF_STRING));

        if (objectInputStream != null) {
            objectInputStream.close();
        }
        if (objectOutputStream != null) {
            objectOutputStream.close();
        }

    } catch (IOException e1) {
        e1.printStackTrace();
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }

The problem is assume that reading one message need 1 second per message, the user may give up to 100 messages, that’s mean it requires 100 seconds to run, in the socket. When the isKeepRun is keep running, there is no problem. But when the user wanna to stop , and call stopWorking, the loop will be escaped, can the socket is closed, during the WorkTask is reading the message. How can I delay the execution of stopWorking if the socket is still reading, if the socket is finished reading, and the stopWorking will be call immediately, but if the socket don’t have any thing to read, I can call the stopWorking in no delay?

Thanks.

Answer 1

There is a problem in your code:

while (isKeepRun) {

socket = serverSocket.accept();
....

}
….

if (socket != null) {

socket.close();

}

You use only one socket reference for all client socket. So if there are more than one client socket, then you will only close the last socket.

As above said, you can use wt.join() to wait for the worker thread to finish, then the main thread will finish. But you have only one reference for client socket. Even you wait, you can only wait for the last socket to finish. All the previous client socket will be closed if you set it to stop.