DatagramSocket和DatagramPacket

DatagramSocket此类表示用来发送和接收数据报包的套接字。

DatagramPacket此类表示数据报包。

package cn.sxt.UdpDemo;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.util.Scanner;

public class ClientB {
    public static void main(String[] args) throws IOException {
        //创建一个datagram socket 用于结束
        DatagramSocket ds = new DatagramSocket(9000);
        while(true) {
            //接收客户端A的信息
            byte[] recbuf = new byte[1024];
            DatagramPacket recDp = new DatagramPacket(recbuf, recbuf.length);
            ds.receive(recDp);
            String recMsg = new String(recbuf,0,recDp.getLength());
            System.out.println("clientA说"+recMsg);
            
            //发送信息到客户端A
            System.out.println("请输入");
            Scanner sc = new Scanner(System.in);
            String msg = sc.next();
            
            System.out.println("开始发送数据："+msg);
            
            InetAddress toIp = InetAddress.getLocalHost();
            byte[] buf = msg.getBytes();
            // 构造数据报包，用来将长度为 length 偏移量为 offset 的包发送到指定主机上的指定端口号。
            DatagramPacket dp = new DatagramPacket(buf,buf.length,toIp,8000);
            //发送数据报
            ds.send(dp);
            //ds.close();
        }
        
    }
}

package cn.sxt.UdpDemo;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.util.Scanner;


public class ClientA {
    public static void main(String[] args) throws IOException {
        //创建数据报套接字并将其绑定到本地主机上的指定端口8000
        DatagramSocket ds = new DatagramSocket(8000);
        while(true) {
            System.out.println("请输入");
            Scanner sc = new Scanner(System.in);
            String msg = sc.nextLine();
            
            //发送信息到客户端B
            System.out.println("开始发送数据："+msg);
            byte[] buf = msg.getBytes();
            
            InetAddress toIp = InetAddress.getLocalHost();
            // 构造数据报包，用来将长度为 length 偏移量为 offset 的包发送到指定主机上的指定端口号。
            DatagramPacket dp = new DatagramPacket(buf,buf.length,toIp,9000);
            
            //用数据报包的套接字,通过8000发送数据报
            ds.send(dp);
            
            //接收客户端B的信息
            byte[] recBuf = new byte[1024];
            DatagramPacket recDp = new DatagramPacket(recBuf,recBuf.length);
            //信息接收
            ds.receive(recDp);
            
            String recMsg = new String(recBuf,0,recDp.getLength());
            System.out.println("clientB说:"+recMsg);
            //ds.close();
        }
        
    }
}