迴圈傳送

package chat;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;

/**
 * 傳送方
 */
public class UdpSenderDemo1 {

    public static void main(String[] args) throws Exception {

        DatagramSocket socket 
 
= new DatagramSocket(8888);

        //準備資料：控制檯讀取：System.in
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

        while (true){
            String data = reader.readLine();
            byte[] dataBytes = data.getBytes();
            DatagramPacket packet = new DatagramPacket(dataBytes, 0 , dataBytes.length, new
 
 InetSocketAddress("localhost", 6666));

            //傳送資料包
            socket.send(packet);

            //當傳送一句 bye 的時候表示結束髮送
            if (data.equals("bye")){
                break;
            }

        }

        //關閉
        socket.close();
    }

}

接收訊息

package chat;

import java.net.DatagramPacket;
 
import java.net.DatagramSocket;

/**
 * 接收方
 */
public class UdpReceiveDemo1 {

    public static void main(String[] args) throws Exception {

        DatagramSocket socket = new DatagramSocket(6666);

        while (true){
            //準備接收資料包
            byte[] container = new byte[1024];
            DatagramPacket packet = new DatagramPacket(container, 0, container.length);

            //接收資料包
            socket.receive(packet); //阻塞式接收包裹

            //讀取資料
            byte[] data = packet.getData();

            String receiveData = new String(data, 0, data.length);

            //接收到的資料
            System.out.println(receiveData);

            //當我們說一聲 bye 的時候就表示斷開連線
            if (receiveData.equals("bye")){
                break;
            }

        }

        //關閉
        socket.close();

    }

}