android UDP通信

     源代码：

MainActivity.java

package com.example.udp;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;

import android.os.Bundle;
import android.os.Message;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.os.Handler;

public class MainActivity extends Activity implements
		android.view.View.OnClickListener {
	public static final String SERVERIP = "127.0.0.1"; 
	public static final int SERVERPORT = 4444;
	public TextView text1;
	public EditText input;
	public Button btn;
	public boolean start;
	public Handler Handler;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		text1 = (TextView) findViewById(R.id.textView1);
		input = (EditText) findViewById(R.id.editText1);
		btn = (Button) findViewById(R.id.button1);
		btn.setOnClickListener(this);
		start = false;
		new Thread(new Server()).start();
		try {
			Thread.sleep(500);
		} catch (InterruptedException e) {

		}
		new Thread(new Client()).start();
		Handler = new Handler() {
			@Override
			public void handleMessage(Message msg) {
				String text = (String) msg.obj;
				text1.append(text);
			}
		};
	}

	public class Client implements Runnable {
		@Override
		public void run() {
			while (start == false) {
			}
			try {
				Thread.sleep(500);
			} catch (InterruptedException e1) {
				// TODO Auto-generated catch block
				e1.printStackTrace();
			}
			try {
				InetAddress serverAddr = InetAddress.getByName(SERVERIP);
				updatetrack("Client: Start connecting\n");
				DatagramSocket socket = new DatagramSocket();
				byte[] buf;
				if (!input.getText().toString().isEmpty()) {
					buf = input.getText().toString().getBytes();
				} else {
					buf = ("Default message").getBytes();
				}
				DatagramPacket packet = new DatagramPacket(buf, buf.length,
						serverAddr, SERVERPORT);
				updatetrack("Client: Sending ‘" + new String(buf) + "’\n");
				socket.send(packet);
				updatetrack("Client: Message sent\n");
				updatetrack("Client: Succeed!\n");
			} catch (Exception e) {
				updatetrack("Client: Error!\n");
			}
		}
	}

	public class Server implements Runnable {
		@Override
		public void run() {
			while (start == false) {
			}
			try {
				InetAddress serverAddr = InetAddress.getByName(SERVERIP);
				updatetrack("\nServer: Start connecting\n");
				DatagramSocket socket = new DatagramSocket(SERVERPORT,
						serverAddr);
				byte[] buf = new byte[17];
				DatagramPacket packet = new DatagramPacket(buf, buf.length);
				updatetrack("Server: Receiving\n");
				socket.receive(packet);
				updatetrack("Server: Message received: ‘"
						+ new String(packet.getData()) + "’\n");
				updatetrack("Server: Succeed!\n");
			} catch (Exception e) {
				updatetrack("Server: Error!\n");
			}
		}
	}

	public void updatetrack(String s) {
		Message msg = new Message();
		String textTochange = s;
		msg.obj = textTochange;
		Handler.sendMessage(msg);
	}

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

	@Override
	public void onClick(View v) {
		// TODO Auto-generated method stub
		if(v.getId()==R.id.button1)
			start = true;
	}
}

activity_main.xml

AndroidManifest.xml