Android TCP套接字不接收数据

我正在使用Android应用程序通过TCP套接字与同一LAN上的PC java应用程序进行通信，发送和接收消息 . 下面是我在Android中用来发送消息并从PC接收回复的Asynctask的代码：

public class Client extends AsyncTask<Void, Void, Void> {

Context context;
String dstAddress;
int dstPort;
String msg;

Client(Context context, String addr, int port, String msg) {
    this.context = context;
    dstAddress = addr;
    dstPort = port;
    this.msg = msg;
}

String reply = "";

@Override
protected Void doInBackground(Void... arg0) {

    Socket socket = null;

    try {
        socket = new Socket(dstAddress, dstPort);

        BufferedWriter dout = new BufferedWriter( new OutputStreamWriter( socket.getOutputStream() ));
        BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));

        //send request
        dout.write(msg);
        dout.flush();
        dout.close();

        //get response
        reply = br.readLine();
        br.close();

    } catch (UnknownHostException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (socket != null) {
            try {
                socket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    return null;
}

@Override
protected void onPostExecute(Void result) {
    super.onPostExecute(result);
    // DISPLAY REPLY CONTENT
    Handler handler =  new Handler(context.getMainLooper());
    handler.post( new Runnable(){
        public void run(){
            Toast.makeText(context, "Server reply: " + reply ,Toast.LENGTH_LONG).show();
        }
    });
}

}

• 我在onPostExcecute的toast中显示了PC的回复 .

• Android通过BufferedWriter发送消息，而PC上的Java应用程序在BufferedReader中接收消息 . （工作正常，经过测试）

• PC收到消息后通过BufferedWriter向android发送响应，其中android在BufferedReader中接收回复，如下所示：br.readLine（） . （这是问题）：根据PC _728132知道我做错了什么，并希望有人可以指出我所缺少的东西 .

下面是处理客户端套接字的服务器线程，该线程基本上在serversocket接受套接字时运行：

static class clientThread extends Thread {

    Socket s = null;
    clientThread(Socket s) //constructor
    {
        this.s = s;
    }

    @Override
    public void run ()
    {
        try
        {
            BufferedReader br = new BufferedReader(new InputStreamReader(s.getInputStream())); //receiving data into a buffered reader

            String dataIn = br.readLine(); // reading the buffered data into a string
                System.out.println("received: " + dataIn);

            //BufferedWriter dout = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
            //dout.write("OK");
            //dout.newLine();

            PrintWriter dout = new PrintWriter(new BufferedWriter(new OutputStreamWriter(s.getOutputStream())), true);
            if(dataIn.equals("Android client"))
            {
                dout.println("OK");
                dout.flush();
                System.out.println("OK sent");
            }


            dout.close();
            br.close();
            s.close();
        }
        catch (IOException e)
        { System.out.println("Error occured"); }

    }
}

所以总结程序，android发送消息“Android客户端”（服务器接收并在控制台上打印没有问题），现在回复，服务器发送“确定”没有问题，但是android一方什么都没收到如前所述，如果我删除dout.close（）;从我发送消息后的android的asynctask，服务器只在程序终止时收到消息，我不明白为什么我必须关闭它才能成功发送消息 .