本文使用socket的長連線，進行訊息的傳送和接受。

1、兩端

client 端，server端

2、兩執行緒

客戶端、伺服器端，各開兩個執行緒，實現讀寫，可以全雙工通訊，非同步傳送，非同步接受。

3、兩注意

程式等待輸入和一直處於等待訊息發來，所以，用到死迴圈。

讀訊息，用到的是行讀，nextLine()方法，所以，一定要在傳送訊息時，在訊息末尾追加加上換行符，否則讀不到。

程式碼：

1、訊息傳送服務類

package com.socket.newChat;

import java.io.IOException;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;

/**
 * Created by Liuxd on 2018-09-15.
 */
public class SendMessageService implements Runnable {
    private Socket socket;
    private String name;

    public SendMessageService(Socket socket, String name) {
        this.socket = socket;
        this.name = name;
    }

    public void run() {
        PrintWriter pWriter = null;
        Scanner scanner = null;
        try {
            pWriter = new PrintWriter(socket.getOutputStream());
            scanner = new Scanner(System.in);
            while (true) {
                String s = scanner.nextLine();
                pWriter.write(name + s + "\n");
                pWriter.flush();
            }

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            scanner.close();
            pWriter.close();
        }

    }
}
 

2、訊息接受服務類

package com.socket.newChat;

import java.io.IOException;
import java.net.Socket;
import java.util.Scanner;

/**
 * Created by Liuxd on 2018-09-15.
 */
public class ReceiveMessageService implements Runnable {
    private Socket socket;

    public ReceiveMessageService(Socket socket) {
        this.socket = socket;
    }

    @Override
    public void run() {
        Scanner scanner = null;
        try {
            scanner = new Scanner(socket.getInputStream());
            while (scanner.hasNext()) {
                System.out.println(scanner.nextLine());
            }

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            scanner.close();
        }
    }
}
 

3、服務端

package com.socket.newChat;

/**
 * Created by Liuxd on 2018-09-15.
 */

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;


public class TestServer {

    public static void main(String[] args) throws IOException {
        ServerSocket serverSocket = new ServerSocket(8081);

        while (true) {
            Socket socket=serverSocket.accept();

            new Thread(new SendMessageService(socket,"伺服器端：")).start();
            new Thread(new ReceiveMessageService(socket)).start();

            System.out.println("請輸入...");

        }
    }
}

 

4、客戶端

package com.socket.newChat;

/**
 * Created by Liuxd on 2018-09-15.
 */

import java.io.IOException;
import java.net.Socket;
import java.net.UnknownHostException;


public class TestClient {

    public static void main(String[] args) {
        try {
            Socket socket = new Socket("127.0.0.1", 8081);

            new Thread(new SendMessageService(socket,"客戶端：")).start();
            new Thread(new ReceiveMessageService(socket)).start();

            System.out.println("請輸入...");

        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}