1：客戶端程式

package com.pb.udp;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.net.DatagramSocket;

/**
 *  使用Sender類來代表客戶端程式，
 * @author ccna_zhang
 *
 */
public class Sender {

	public static void main(String[] args) {
		String msg = "Hello, World";
		byte[] buf = msg.getBytes();
		try {
			InetAddress address = InetAddress.getByName("192.168.1.80");  //伺服器地址
			int port = 8080;  //伺服器的埠號
			//建立傳送方的資料報資訊
			DatagramPacket dataGramPacket = new DatagramPacket(buf, buf.length, address, port);
			
			DatagramSocket socket = new DatagramSocket();  //建立套接字
			socket.send(dataGramPacket);  //通過套接字傳送資料
			
			//接收伺服器反饋資料
			byte[] backbuf = new byte[1024];
			DatagramPacket backPacket = new DatagramPacket(backbuf, backbuf.length);
			socket.receive(backPacket);  //接收返回資料
			String backMsg = new String(backbuf, 0, backPacket.getLength());
		    System.out.println("伺服器返回的資料為:" + backMsg);
		    
			socket.close();
			
		} catch (UnknownHostException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}
 

2：伺服器端程式

package com.pb.udp;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketAddress;
import java.net.UnknownHostException;

/**
 * 伺服器端程式
 * @author ccna_zhang
 *
 */
public class Receiver {

	public static void main(String[] args) {
		
		try {
			InetAddress address = InetAddress.getLocalHost();
			int port = 8080;  
			
			//建立DatagramSocket物件
			DatagramSocket socket = new DatagramSocket(port, address);
			
			byte[] buf = new byte[1024];  //定義byte陣列
			DatagramPacket packet = new DatagramPacket(buf, buf.length);  //建立DatagramPacket物件
			
			socket.receive(packet);  //通過套接字接收資料
			
			String getMsg = new String(buf, 0, packet.getLength());
			System.out.println("客戶端傳送的資料為：" + getMsg);
			
			//從伺服器返回給客戶端資料
			InetAddress clientAddress = packet.getAddress(); //獲得客戶端的IP地址
			int clientPort = packet.getPort(); //獲得客戶端的埠號
			SocketAddress sendAddress = packet.getSocketAddress();
			String feedback = "Received";
			byte[] backbuf = feedback.getBytes();
			DatagramPacket sendPacket = new DatagramPacket(backbuf, backbuf.length, sendAddress); //封裝返回給客戶端的資料
			socket.send(sendPacket);  //通過套接字反饋伺服器資料
			
			socket.close();  //關閉套接字
			
		} catch (UnknownHostException e) {
			e.printStackTrace();
		} catch(IOException e) {
			e.printStackTrace();
		}
	}
}
 

3：程式執行結果

伺服器端：

    客戶端傳送的資料為：Hello, World

客戶端：

   伺服器返回的資料為:Received