效果图：

开启服务端

客户端一

客户端二

客户端三

实现代码：

客户端类

import java.io.IOException;

import java.net.ServerSocket;

import java.net.Socket;

import java.util.ArrayList;

import java.util.List;

public class SocketServer {

	public static List<Socket> socketList=new ArrayList<Socket>();

	public static void main(String[] args) throws IOException {

		ServerSocket serverSocket = new ServerSocket(8088);

		System.out.println("聊天服务已开启");

		while(true){

			//当客户端发出请求，服务端建立的通向客户端的专属通道

			Socket socket = serverSocket.accept();

			socketList.add(socket);

			new Thread(new ServerThread(socket)).start();

		}

	}

}

服务器线程类

import java.io.BufferedReader;

import java.io.InputStreamReader;

import java.io.PrintWriter;

import java.net.Socket;

public class ServerThread implements Runnable{

	public Socket socket;

	public ServerThread(Socket socket) {

		super();

		this.socket = socket;

	}

	@Override

	public void run() {

		try {

			BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));

			while (true) {

				String readLine = bufferedReader.readLine();

				for (Socket item : SocketServer.socketList) {

					PrintWriter pw=new PrintWriter(item.getOutputStream());

					pw.println("用户"+socket.getPort()+"说"+readLine);

					pw.flush();

				}

			}

		} catch (Exception e) {

		}

	}

}

读取的线程类

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.net.Socket;

public class ReaderThread implements Runnable{

	public Socket socket;

	public ReaderThread(Socket socket) {

		super();

		this.socket = socket;

	}

	@Override

	public void run() {

		try {

			BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));

			while (true) {

				String data=bufferedReader.readLine();

				System.out.println(data);

			}

		} catch (IOException e) {

			e.printStackTrace();

		}

	}

}

写出的线程类

import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.InputStreamReader;

import java.io.PrintWriter;

import java.net.Socket;

public class WriterThread implements Runnable{

	public Socket socket;

	public WriterThread(Socket socket) {

		super();

		this.socket = socket;

	}

	@Override

	public void run() {

		try {

			BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

			PrintWriter printWriter = new PrintWriter(socket.getOutputStream());

			while (true) {

				String data=br.readLine();

				printWriter.println(data);

				printWriter.flush();

			}

		} catch (Exception e) {

		}

	}

}

客户端类

import java.io.IOException;

import java.net.Socket;

import java.net.UnknownHostException;

public class SocketClient {

	public static void main(String[] args) throws UnknownHostException, IOException {

		Socket socket = new Socket("127.0.0.1",8088);

		System.out.println("您已上线");

		new Thread(new WriterThread(socket)).start();

		new Thread(new ReaderThread(socket)).start();

	}

}