import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;public class UdpRecv {public static void main(String[] args) throws Exception{//绑定本机断开DatagramSocket ds = new DatagramSocket(8080);byte[] buf = new byte[1024];DatagramPacket dp = new DatagramPacket(buf,buf.length);//接收数据包
        ds.receive(dp);//取出数据报内容String str = new String(dp.getData(),0,dp.getLength());System.out.println(str);//打印发送方的地址System.out.println("ip:"+dp.getAddress().getHostAddress()+"port:"+dp.getPort());ds.close();}
}

package com.bvin.test.udp;import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;import android.app.Activity;
import android.content.Context;
import android.net.wifi.WifiInfo;
import android.net.wifi.WifiManager;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.EditText;public class MainActivity extends Activity {/** Called when the activity is first created. */EditText et ;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);et =  new EditText(this);setContentView(et);WifiManager wMan = (WifiManager)getSystemService(Context.WIFI_SERVICE);if(!wMan.isWifiEnabled()){wMan.setWifiEnabled(true);}WifiInfo wifiInfo = wMan.getConnectionInfo();Log.e("ip", intToIp(wifiInfo.getIpAddress()));//本机ip（仅wifi环境）
    }//把获取的整形转换成字符型private String intToIp(int i) {         return (i & 0xFF ) + "." +         ((i >> 8 ) & 0xFF) + "." +         ((i >> 16 ) & 0xFF) + "." +         ( i >> 24 & 0xFF) ;   }@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// TODO Auto-generated method stubmenu.add("发送");return super.onCreateOptionsMenu(menu);}@Overridepublic boolean onOptionsItemSelected(MenuItem item) {// TODO Auto-generated method stubif(item.getItemId()==0){DatagramSocket ds;try {//套接字ds = new DatagramSocket();//发送内容String str = et.getText().toString();//构建数据报（内容+地址）DatagramPacket dp = new DatagramPacket(str.getBytes(),str.length(),InetAddress.getByName("192.168.0.102"),8080);//把数据报发送出去
                ds.send(dp);//关闭套接字
                ds.close();} catch (IOException e) {// TODO Auto-generated catch block
                e.printStackTrace();}}return super.onOptionsItemSelected(item);}}