Question

我已经构建了一个upd服务器监听代码，可以在我的手机上上传并收听数据包。此代码将编译但由于某种原因它不会加载到我的手机。我在任何地方都没有看到任何错误。为什么会这样？这是我的整个主要活动代码：

package roman10.tutorial.udpcommserver;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
import java.net.InetSocketAddress;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;

public class UdpServer extends Activity {
/** Called when the activity is first created. */
private TextView textView; 
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    textView = (TextView) findViewById(R.id.text1);
    runUdpServer();
}
private static final int UDP_SERVER_PORT = 4000;
private static final int MAX_UDP_DATAGRAM_LEN = 1500;
private static final String ipAdd = new String("172.30.42.80");

private void runUdpServer() {
    String lText;

//      byte[] lMsg = new byte[MAX_UDP_DATAGRAM_LEN];
//      DatagramPacket dp = new DatagramPacket(lMsg, lMsg.length);
//      DatagramSocket ds = null;
        byte buffer[] = new byte[MAX_UDP_DATAGRAM_LEN];
        DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
        try {
//          ds = new DatagramSocket(UDP_SERVER_PORT);
//          //disable timeout for testing
//          //ds.setSoTimeout(100000);
//          ds.receive(dp);
            //lText = new String(lMsg, 0, dp.getLength());
//          Log.i("UDP packet received", lText);
//          textView.setText(lText);
            DatagramSocket s = new DatagramSocket();
            InetSocketAddress address = new InetSocketAddress(ipAdd, UDP_SERVER_PORT);
            s.bind(address);

        lText = new String(buffer,0,packet.getLength());
        Log.i("UDP packet received", lText);
        textView.setText(lText);

        System.out.println("Waiting...");
        s.receive(packet);
        if (s != null) {
            s.close();
        }
//          s.close();
            System.out.println("Received!");
        } catch (SocketException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            System.out.print("we are done ");
        }

    }
}

Answer 1

1）你没有从你的onCreate回来（直到你收到了什么）。活动无法继续开始（当然不会调用onStart，onResume等。

2）然后你在主线程上进行I / O，甚至是网络I / O，不推荐，并且通常在android上检测不允许并强制关闭。您将获得NetworkOnMainThreadException

幸运的是，这些问题都可以通过创建一个单独的线程并在那里执行runUdpServer()来解决。简短的例子，而不是：

runUdpServer();

做的：

Thread thread = new Thread() {
  public void run() {
    runUdpServer();
  }
};
thread.start();

UDP服务器android应用程序不会上传到手机

1 个答案: