UDP-2022-12-19

发送端：

package Lesson02;

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

//UDP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、建立一个包
        String msg = "你好，很高兴认识你";
        InetAddress localhost = InetAddress.getByName("localhost");
        int port =9090;
        // 数据，数据的长度起始，长度，发送给谁，端口
        DatagramPacket packet = new DatagramPacket(msg.getBytes(),0,msg.getBytes().length,localhost,port);
        //3、发包
        socket.send(packet);

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

接收端 receiver

package Lesson02;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
//还是要等待客户端的连接
public class UdpServerDemo01 {
    public static void main(String[] args) throws Exception {
        //1、开放端口
        DatagramSocket socket = new DatagramSocket(9090);

        //2、接收数据包
        byte[] buffer = new byte[1024];
        int len;
        DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length);

        socket.receive(packet);
        System.out.println(packet.getAddress());
        System.out.println(new String(packet.getData(),0,packet.getLength()));
        //3.关闭
        socket.close();
    }
}