Java学习之路--网络编程相关03

package com.kuang.lesson03;

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

//2023.3.6 UDP通信方式实现发送消息 ----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  发送消息
        String msg = "你好啊，服务器！";
        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();
    }
}

//

package com.kuang.lesson03;

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

//2023.3.6 UDP 服务器端  ---还是要等待客户端的连接
public class UdpServerDemo01 {
    public static void main(String[] args) throws Exception {
        //开放端口
        DatagramSocket socket = new DatagramSocket(9090);
        //接受数据包
        byte[] buffer = new byte[1024];
        DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);

        socket.receive(packet);//阻塞接收
        System.out.println(packet.getAddress().getHostAddress());
        System.out.println(new String(packet.getData(),0,packet.getLength()));
        //关闭连接
        socket.close();
    }
}