java网络原理《狂神说》实现UDP双方通信（含代码）

Posted 2021-12-22 轻狂书生han

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UDP

发信息：不用链接，需要知道对方的地址！

发送消息

package comip.study.lesson03;

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


//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，要发送给谁
        DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length, localhost, port);

        //3.发个包
        socket.send(packet);

        //关闭流
        socket.close();

接收端

package comip.study.lesson03;

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

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

        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();

咨询

发送端

package comip.study.chat;

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

public class UdpSenderDemo01 
    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();

接收端

 	package comip.study.chat;

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

public class UdpReceiveDemo01 
    public static void main(String[] args) throws Exception 
        DatagramSocket socket = new DatagramSocket(6666);


        while (true)
            //准备接收包裹
            byte[] container = new byte[1024];

            DatagramPacket packet = new DatagramPacket(container,0,container.length);
            socket.receive(packet);//阻塞式接受包裹

            //断开连接 bye
            byte[] data = packet.getData();
            String receiveDatas = new String(data,0,data.length);
            System.out.println(receiveDatas);

            if (receiveDatas.equals("bye"))
                break;
            


        

        socket.close();

修改为以下的代码，让他一直可以发送

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;

在线咨询：两人都可以是发送方，也可以都是接收方

发送方

package comip.study.chat;

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

public class TalkSend implements Runnable
    DatagramSocket socket = null;
    BufferedReader reader = null;

    private int fromPort;
    private String toIP;
    private int toPort;


    public TalkSend(int fromIP, String toIP, int toPort) 
        this.fromPort = fromPort;
        this.toIP = toIP;
        this.toPort = toPort;

        try 
            socket = new DatagramSocket(fromPort);
            reader = new BufferedReader(new InputStreamReader(System.in));
        catch (Exception e) 

            e.printStackTrace();
        
    

    @Override
    public void run() 
        //准备数据，控制台读取 System.in


        while (true)
            try 
                String data = reader.readLine();
                byte[] datas = data.getBytes();
                DatagramPacket packet = new DatagramPacket(datas,0,datas.length,new InetSocketAddress(this.toIP,this.toPort));

                socket.send(packet);
                if (data.equals("bye"))
                    break;
                
             catch (IOException e) 
                e.printStackTrace();
            

        


        socket.close();

接收方

 package comip.study.chat;

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

public class TalkReceive implements Runnable
    DatagramSocket socket = null;
    private int port;
    private String msgFrom;

    public TalkReceive(int port,String msgFrom) 
        this.port = port;
        this.msgFrom = msgFrom;
        try 
            socket = new DatagramSocket(port);
         catch (SocketException e) 
            e.printStackTrace();
        
    

    @Override
    public void run() 

        while (true)
            //准备接收包裹
            byte[] container = new byte[1024];

            DatagramPacket packet = new DatagramPacket(container,0,container.length);
            try 
                socket.receive(packet);//阻塞式接受包裹
                //断开连接 bye
                byte[] data = packet.getData();
                String receiveDatas = new String(data,0,data.length);
                System.out.println(msgFrom+receiveDatas);

                if (receiveDatas.equals("bye"))
                    break;
                
             catch (IOException e) 
                e.printStackTrace();
            




        

        socket.close();

线程一：学生

package comip.study.chat;

public class TalkStudent 
    public static void main(String[] args) 
        //开启两个线程
        new Thread(new TalkSend(7777,"localhost",9999)).start();
        new Thread(new TalkReceive(8888,"老师：")).start();

线程二：老师

package comip.study.chat;

public class TalkTeacher
    public static void main(String[] args) 
        new Thread(new TalkSend(5555,"localhost",8888)).start();
        new Thread(new TalkReceive(9999,"学生：")).start();

注意端口问题！