java網路原理（三）《狂神說》實現UDP雙方通訊（含程式碼）

阿新 • • 發佈：2021-12-21

UDP

發信息：不用連結，需要知道對方的地址！

傳送訊息

package comip.study.lesson03;

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


//不需要連線伺服器
public class UdpClientDemo01 {
    public static void main(String[] args) throws Exception {
        //1.建立一個Socket
        DatagramSocket socket = new DatagramSocket();

        //2.建個包
        String msg = "你好啊，伺服器";

        //傳送給誰
        InetAddress localhost = InetAddress.getByName("localhost");
        int port = 9090;
        //資料，資料的長度，要傳送給誰
        DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length, localhost, port);

        //3.發個包
        socket.send(packet);

        //關閉流
        socket.close();
    }
}

接收端

package comip.study.lesson03;

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

//還是要等待客戶端的連線！
public class UdpServerDemo01 {
    public static void main(String[] args) throws Exception {
        //開放埠
        DatagramSocket socket = new DatagramSocket(9090);
        //接收資料
        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()));

        //關閉連線
        socket.close();


    }

}

諮詢

傳送端

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);

        //準備資料，控制檯讀取 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){
            //準備接收包裹
            byte[] container = new byte[1024];

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

            //斷開連線 bye
            byte[] data = packet.getData();
            String receiveDatas = new String(data,0,data.length);
            System.out.println(receiveDatas);

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


        }

        socket.close();

    }
}

修改為以下的程式碼，讓他一直可以傳送

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;
            }

線上諮詢：兩人都可以是傳送方，也可以都是接收方

傳送方

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() {
        //準備資料，控制檯讀取 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){
            //準備接收包裹
            byte[] container = new byte[1024];

            DatagramPacket packet = new DatagramPacket(container,0,container.length);
            try {
                socket.receive(packet);//阻塞式接受包裹
                //斷開連線 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();
    }
}

執行緒一：學生

package comip.study.chat;

public class TalkStudent {
    public static void main(String[] args) {
        //開啟兩個執行緒
        new Thread(new TalkSend(7777,"localhost",9999)).start();
        new Thread(new TalkReceive(8888,"老師：")).start();
    }
}

執行緒二：老師

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,"學生：")).start();
    }
}

注意埠問題！

使用黑框口實現通訊：

開啟檔案地址

開啟cmd定位class檔案路徑

直接不能執行，需要退到包名

返回到com

沒有出現報錯就表示啟動起來了

啟動老師端

實現通訊

這裡由於編碼格式不同，黑窗口出現亂碼情況，但是我們基本簡單實現了UDP的通訊。