UDP

UDP

发短信：不用连接，需要知道对方的地址！

发送端

package com.hua;

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("127.0.0.1");
        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,9090);
        //3、发送包
        socket.send(packet);
        //4、关闭流
        socket.close();
    }
}

接收端

package com.hua;

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 {
        //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);//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();
    }
}

循环发送消息

package com.hua;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.*;
import java.util.stream.Stream;

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();
    }
}

package com.hua;

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);

        while(true){
            //准备接收包裹
            byte[] container = new byte[1024];
            DatagramPacket packet = new DatagramPacket(container,0,container.length);
            socket.receive(packet);//阻塞式接收包裹

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

            if (data.equals("bye")){
                break;
            }

        }
        socket.close();
    }
}

 在线咨询：两个人都可以是发送方，也都可以是接收方！

package com.hua;

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

public class TalkSend implements Runnable{
    DatagramSocket socket = null;
    BufferedReader reader =null;
    private int fromPort;
    private String toIP;
    private int toPort;

    public TalkSend(int fromPort, 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 (SocketException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {

        while(true){
            String data = null;
            try {
                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();
    }
}

package com.hua;

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

public class TalkReceive implements Runnable{
    DatagramSocket socket = null;
    DatagramPacket packet = 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];
            packet = new DatagramPacket(container,0,container.length);
            try {
                socket.receive(packet);//阻塞式接收包裹
            } catch (IOException e) {
                e.printStackTrace();
            }

            //断开连接 bye
            byte[] data = packet.getData();
            String receivedata = new String(data, 0, packet.getLength());
            System.out.println(msgFrom+":"+receivedata);

            if (receivedata.equals("bye")){
                break;
            }
        }
        socket.close();
    }
}

package com.hua;

public class TalkTeacher {
    public static void main(String[] args) {
        new Thread(new TalkSend(6666,"localhost",8888)).start();
        new Thread(new TalkReceive(9999,"学生")).start();
    }
}

package com.hua;

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();
    }
}