UDP消息发送

发送端

package com.kuang.lesson03;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;

//不需要连接服务器
public class UdpClientDemo01 {
    public static void main(String[] args) throws Exception {
        //1.建立一个Socket
        DatagramSocket socket = new DatagramSocket();
//        2.建个包
        String msg="你好啊，服务器！";
//        发送给谁
        InetAddress localhost = InetAddress.getByName("localhost");
        int port=9090;
        //数据，数据的长度起始，要发送给谁
        DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length, localhost, port);


        //3.发送包
        socket.send(packet);



        //4.关闭流
        socket.close();
    }

}

接受端

package com.kuang.lesson03;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
//等待客户端的连接
public class UdpServerDemo01 {
    public static void main(String[] args) throws Exception {
        //开放端口
         DatagramSocket socket = new DatagramSocket(9090);
//       接收数据包
        byte[] buffer = new byte[1024];
        DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length);

        socket.receive(packet);
        System.out.println(packet.getAddress().getHostAddress());
        System.out.println(new String(packet.getData(),0,packet.getData().length));
      //关闭连接
        socket.close();

    }
}

UDP实现聊天

接收端

package com.kuang.chat;

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

public class UdpReceiveDemo01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(6666);
         //准备接收包裹

        while (true){
            byte[] container = new byte[1024];
            DatagramPacket packet = new DatagramPacket(container,0,container.length);
            socket.receive(packet);//阻塞式接收包裹
            //断开连接判断 bye
            byte[] data = packet.getData();
            String datas = new String(data, 0, data.length);
            System.out.println(datas);
            if (datas.equals("bye")){
                break;
            }


        }
            socket.close();
    }

}

//发送端多发送了一个空行换位符，所以if里是false，要加个清除换位符，就可以实现关闭连接！
if (datas.trim().equals("bye")){
    break;
}

 

发送端

package com.kuang.chat;

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

public class UdoSenderDemo01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(8888);
        //准备数据：控制台读取 System.in
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        while (true) {
            String data = reader.readLine();
            byte[] datas = data.getBytes();

            DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress("localhost", 6666));
            socket.send(packet);
            if (data.equals("bye")) {
                break;
            }

        }
        socket.close();


    }

}