java 利用UDP协议 通信

package udp;

import java.net.* ;

public class UdpTest

{

public static void main(String []args)

{

if (args.length > 0)

runServer();

else

runClient() ;

}

static public void runServer() //服务器端

{

try

{

DatagramSocket ss = new DatagramSocket(6666); //创建数据包套接字

byte date[]=new byte[100];

while(true)

{

DatagramPacket dp=new DatagramPacket (date,100) ; //创建数据包

ss.receive(dp);

System.out.println(new String(date,0,dp.getLength())); //将受到的数据写入

String str="welcome you";

DatagramPacket dp1=new DatagramPacket(str.getBytes(),str.length(),dp.getAddress(),dp.getPort());

ss.send(dp1);

}

}

catch(Exception e)

{

e.printStackTrace();

}

}

static public void runClient() //客户端

{

try{

DatagramSocket ss = new DatagramSocket(); //创建数据包套接字

String str="hello i am zhangsan !";

DatagramPacket p=new DatagramPacket(str.getBytes(),str.length(),InetAddress.getByName("LocalHost"),6666);

ss.send(p);

byte ch[]=new byte[100];

DatagramPacket p1=new DatagramPacket(ch,100) ;

ss.receive(p1);

System.out.println(new String(ch,0,p1.getLength()));

ss.close();

}

catch(Exception e)

{

e.printStackTrace();

}

}



}