import java.net.*;  
public class UdpC {  
    public static void main(String[] args) throws Exception {  
     DatagramSocket dS=new  DatagramSocket(3000);     
      String str="Hello world"; //要傳送的資料  
      DatagramPacket dp=new DatagramPacket(str.getBytes(),str.length(),  
      InetAddress.getByName("localhost"), 8001);  
      dS.send(dp);  
      dS.close();  
    }  
}  
 

import java.net.*;  
public class Udp {  
    public static void main(String[] args) throws Exception {  
   byte[]buf=new byte[1024];//建立一個長度為1024的位元組陣列，用於接收資料  
   DatagramSocket dS=new  DatagramSocket(8001);//設定監聽埠號為8001  
   DatagramPacket dp=new DatagramPacket(buf,1024);  
    System.out.println("接收資料:");  
    dS.receive(dp);  
    String str=new String(dp.getData(),0,dp.getLength());  
    System.out.println(str);  
    dS.close();  
    }  
}