import java.net.DatagramPacket;import java.net.DatagramSocket;import java.net.InetAddress;public class UDPsend {	/**	 * @param args	 */	public static void main(String[] args) throws Exception {		// TODO Auto-generated method stub		DatagramSocket ds=new DatagramSocket();		String string="hello world";		DatagramPacket dp=new DatagramPacket(string.getBytes(), string.length(),InetAddress.getByName("127.0.0.1"),4321);		ds.send(dp);		ds.close();	}}

 

import java.net.DatagramPacket;import java.net.DatagramSocket;public class UDPrecv {	/**	 * @param args	 */	public static void main(String[] args) throws Exception {		// TODO Auto-generated method stub		DatagramSocket ds=new DatagramSocket(4321);		byte[] buf=new byte[1024];		DatagramPacket dp=new DatagramPacket(buf, 1024);		ds.receive(dp);		String strRecv=new String(dp.getData(),0,dp.getLength())+"from"+dp.getAddress().getHostAddress()+":"+dp.getPort();		System.out.println(strRecv);		ds.close();	}}