如何在android中使用UDP套接字? [英] How to use UDP sockets in android?

问题描述

我正在尝试在 android 中使用 UDP 套接字，在这里我从 android 模拟器发送我的字符串并通过我的 Java 程序在 PC 上接收，但是我的 Java 程序没有收到任何东西，尽管当我使用 Java 程序作为两个客户端时和服务器(我制作了两个不同的 Java 程序).

I am trying to use UDP sockets in a android, here I send my string from android emulator and receive that by my Java program on PC, but my Java program does not receive anything, although when I used Java program as both client and server (I made two different Java programs) it worked.

这是我的 android 主要活动:

This is my android main activity :

public class First extends Activity {
Button b;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    b = (Button) findViewById(R.id.button1);
    b.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) {
            // TODO Auto-generated method stub
            Thread t = new Thread(new Second());
            t.start();
        }
    });

这是我在 android 中的第二堂课:

Here is my second class in android :

    public class Second implements Runnable {
Second()
{
    run();
}
public void run() {
    // TODO Auto-generated method stub
    try {

        String messageStr = "Hello Android!";
        int server_port = 9876;
        DatagramSocket s = new DatagramSocket();
        InetAddress local = InetAddress.getByName("127.0.0.1");
        int msg_length = messageStr.length();
        byte[] message = messageStr.getBytes();
        DatagramPacket p = new DatagramPacket(message, msg_length, local,
                server_port);
        s.send(p);
    } catch (Exception e) {

    }
}
}

这是我在 PC 上的 Java 代码:

This is my Java code on PC:

    public static void main(String args[]) throws Exception
    {
            DatagramSocket serverSocket = new DatagramSocket(9876);
            byte[] receiveData = new byte[1024];
            byte[] sendData = new byte[1024];
            while(true)
            {
                    DatagramPacket receivePacket = new     DatagramPacket(receiveData,receiveData.length);
                    serverSocket.receive(receivePacket);
                    String sentence = new String(receivePacket.getData(),0,receivePacket.getLength());
                    InetAddress IPAddress = receivePacket.getAddress();
                    int port = receivePacket.getPort();
                    System.out.println("MESSAGE RECEIVED  "+sentence+"  "+IPAddress+"         "+port);
            }
     }

推荐答案

在您的 Android 仿真(和 Android 设备)上，127.0.0.1 表示 Android 仿真机，而不是主机 PC.您可以在 10.0.2.2

On your Android emulation (and Android device), 127.0.0.1 means the Android emulation machine, not the host PC. You can access your host at 10.0.2.2

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