服务端代码：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;/*** 发送消息线程*/
class Send extends Thread{private Socket socket;public Send(Socket socket){this.socket  =socket;}@Overridepublic void run() {this.sendMsy();}/*** 发送消息*/private void sendMsy(){Scanner scanner =null;PrintWriter pw =null;try{scanner =new Scanner(System.in);pw =new PrintWriter(this.socket.getOutputStream());while(true){String str =scanner.nextLine();pw.println(str);pw.flush();}}catch (Exception e){e.printStackTrace();}finally {if (scanner!=null){scanner.close();}if (pw!=null){pw.close();}if (socket!=null){try {socket.close();} catch (IOException e) {e.printStackTrace();}}}}
}/*** 接收消息的线程*/
class receive extends Thread{private Socket socket=null;public receive(Socket socket){this.socket =socket;}@Overridepublic void run() {this.receiveMsg();}/*** 用于接收对方消息*/private void receiveMsg(){BufferedReader br =null;try{br =new BufferedReader(new InputStreamReader(this.socket.getInputStream()));while(true){String mr = br.readLine();System.out.println("A说："+mr);}}catch (Exception e){e.printStackTrace();}finally {if (br!=null){try {br.close();} catch (IOException e) {e.printStackTrace();}}}}
}public class ChatSocketServer {public static void main(String[] args) {ServerSocket serverSocket =null;try{serverSocket =new ServerSocket(8888);System.out.println("服务端已启动等待连接");Socket socket = serverSocket.accept();System.out.println("连接成功！");new Send(socket).start();new receive(socket).start();}catch(Exception e){e.printStackTrace();}finally {if (serverSocket!=null){try {serverSocket.close();} catch (IOException e) {e.printStackTrace();}}}}
}

客户端代码：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;public class ChatSocketClient {public static void main(String[] args) {try {Socket socket =new Socket("127.0.0.1",8888);System.out.println("连接成功！");new ClientSend(socket).start();new Clientreive(socket).start();} catch (IOException e) {e.printStackTrace();}}
}
/*** 用于发送消息线程类*/
class ClientSend extends Thread{@Overridepublic void run() {this.sendMsy();}private Socket socket;public ClientSend(Socket socket){this.socket  =socket;}/*** 发送消息*/private void sendMsy(){Scanner scanner =null;PrintWriter pw =null;try{scanner =new Scanner(System.in);pw =new PrintWriter(this.socket.getOutputStream());while(true){String str =scanner.nextLine();pw.println(str);pw.flush();}}catch (Exception e){e.printStackTrace();}finally {if (scanner!=null){scanner.close();}if (pw!=null){pw.close();}if (socket!=null){try {socket.close();} catch (IOException e) {e.printStackTrace();}}}}
}/***用于接收消息线程类*/
class Clientreive extends Thread{private Socket socket=null;public Clientreive(Socket socket){this.socket =socket;}@Overridepublic void run() {this.receiveMsg();}/*** 用于接收对方消息*/private void receiveMsg(){BufferedReader br =null;try{br =new BufferedReader(new InputStreamReader(this.socket.getInputStream()));while(true){String mr = br.readLine();System.out.println("B说："+mr);}}catch (Exception e){e.printStackTrace();}finally {if (br!=null){try {br.close();} catch (IOException e) {e.printStackTrace();}}}}
}

运行服务端代码后，再运行客户端代码，即可实现一对一聊天。

结果：