我写UDP服务器简单的方法：

I write simple method for udp server:

 private void runUdpServer() {
        String message;
        byte[] lmessage = new byte[MAX_UDP_DATAGRAM_LEN];
        DatagramPacket packet = new DatagramPacket(lmessage, lmessage.length);
        DatagramSocket socket = null;
        try {
            socket = new DatagramSocket(UDP_SERVER_PORT);
            socket.receive(packet);
            message = new String(lmessage, 0, packet.getLength());
            textMessage.setText(message);
        } catch (SocketException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (socket != null) {
                socket.close();
            }
        }

    }

我怎么能做出这种服务器运行，并监听消息。我的onCreate使用这种方法，但是当我发送消息客户端我看到这个消息，但是当我把第二个消息我不;吨看到这第二个。仅第一消息。我怎样才能让获得新的信息？

How can I make to this server run and listen for messages. I use this method in onCreate, but when I send message from client I saw this message, but when I send second message I don;t see this second. Only that first message. How can I make to get new messages?

编辑： 这是我的code现在：

This is my code now:

@SuppressLint("NewApi")
public class Server extends Activity {

    private static final int UDP_SERVER_PORT = 2004;
    private static final int MAX_UDP_DATAGRAM_LEN = 1500;
    private TextView textMessage;
    private RunServerInThread runServer = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_server);

        if (android.os.Build.VERSION.SDK_INT > 9) {
            StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
            StrictMode.setThreadPolicy(policy);
          }

        textMessage = (TextView) findViewById(R.id.messageText);
        runServer = new RunServerInThread();
        runServer.start();
    }
    private Runnable updateTextMessage = new Runnable() {
        public void run() {
            if (runServer == null) return;
            textMessage.setText(runServer.getLastMessage());
        }
    };


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.server, menu);
        return true;
    }


    private void runUdpServer() {
        String message;
        byte[] lmessage = new byte[MAX_UDP_DATAGRAM_LEN];
        DatagramPacket packet = new DatagramPacket(lmessage, lmessage.length);
        DatagramSocket socket = null;
        try {
            socket = new DatagramSocket(UDP_SERVER_PORT);
            socket.receive(packet);
            message = new String(lmessage, 0, packet.getLength());
            textMessage.setText(message);
        } catch (SocketException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (socket != null) {
                socket.close();
            }
        }

    }

    private class RunServerInThread extends Thread{
        private boolean keepRunning = true;
        private String lastmessage = "";

        @Override
        public void run() {
            String message;
            byte[] lmessage = new byte[MAX_UDP_DATAGRAM_LEN];
            DatagramPacket packet = new DatagramPacket(lmessage, lmessage.length);
            DatagramSocket socket = null;
            while(keepRunning){
            try {
                socket = new DatagramSocket(UDP_SERVER_PORT);
                socket.receive(packet);
                message = new String(lmessage, 0, packet.getLength());
                textMessage.setText(message);
            } catch (SocketException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                if (socket != null) {
                    socket.close();
                }
            }
        }
        }

       public String getLastMessage() {
            return lastmessage;
        }
    }
}

和我得到错误：

05-30 12:18:48.562: E/AndroidRuntime(17987): FATAL EXCEPTION: Thread-1233
05-30 12:18:48.562: E/AndroidRuntime(17987): android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
05-30 12:18:48.562: E/AndroidRuntime(17987):    at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:4746)
05-30 12:18:48.562: E/AndroidRuntime(17987):    at android.view.ViewRootImpl.requestLayout(ViewRootImpl.java:823)
05-30 12:18:48.562: E/AndroidRuntime(17987):    at android.view.View.requestLayout(View.java:15469)
05-30 12:18:48.562: E/AndroidRuntime(17987):    at android.view.View.requestLayout(View.java:15469)
05-30 12:18:48.562: E/AndroidRuntime(17987):    at android.view.View.requestLayout(View.java:15469)
05-30 12:18:48.562: E/AndroidRuntime(17987):    at android.view.View.requestLayout(View.java:15469)
05-30 12:18:48.562: E/AndroidRuntime(17987):    at android.widget.RelativeLayout.requestLayout(RelativeLayout.java:318)
05-30 12:18:48.562: E/AndroidRuntime(17987):    at android.view.View.requestLayout(View.java:15469)
05-30 12:18:48.562: E/AndroidRuntime(17987):    at android.widget.TextView.checkForRelayout(TextView.java:6368)
05-30 12:18:48.562: E/AndroidRuntime(17987):    at android.widget.TextView.setText(TextView.java:3622)
05-30 12:18:48.562: E/AndroidRuntime(17987):    at android.widget.TextView.setText(TextView.java:3480)
05-30 12:18:48.562: E/AndroidRuntime(17987):    at android.widget.TextView.setText(TextView.java:3455)
05-30 12:18:48.562: E/AndroidRuntime(17987):    at pl.udpconnection.server.Server$RunServerInThread.run(Server.java:89)

我如何解决这个问题？

How I can solve this problem?

推荐答案

把code你进入一个循环，并把这个循环到它自己的线程，以便它不会阻塞UI线程。

Put the code you have into a loop, and put this loop into its own thread so that it doesn't block the UI thread.

使用runOnUiThread（）从这个新的线程更新UI。

Use runOnUiThread() to update the UI from this new thread.

例如：

private MyDatagramReceiver myDatagramReceiver = null;

protected void onResume() {
    myDatagramReceiver = new MyDatagramReceiver();
    myDatagramReceiver.start();
}

protected void onPause() {
    myDatagramReceiver.kill();
}

private class MyDatagramReceiver extends Thread {
    private boolean bKeepRunning = true;
    private String lastMessage = "";

    public void run() {
        String message;
        byte[] lmessage = new byte[MAX_UDP_DATAGRAM_LEN];
        DatagramPacket packet = new DatagramPacket(lmessage, lmessage.length);

        try {
            DatagramSocket socket = new DatagramSocket(UDP_SERVER_PORT);

            while(bKeepRunning) {
                socket.receive(packet);
                message = new String(lmessage, 0, packet.getLength());
                lastMessage = message;
                runOnUiThread(updateTextMessage);
            }
        } catch (Throwable e) {
            e.printStackTrace();
        }

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

    public void kill() { 
        bKeepRunning = false;
    }

    public String getLastMessage() {
        return lastMessage;
    }
}

private Runnable updateTextMessage = new Runnable() {
    public void run() {
        if (myDatagramReceiver == null) return;
        textMessage.setText(myDatagramReceiver.getLastMessage());
    }
};