代码演示如下：

服务端

public class Server {
    public static void main(String[] args) throws Exception{
        System.out.println("服务端开启！");
        //1.创建ServerSocket的对象，同时为服务端注册端口。
        ServerSocket serverSocket = new ServerSocket(8080);
        while (true) {
            //2.使用serverSocket对象，调用一个accept方法，等待客户端的连接请求
            Socket socket = serverSocket.accept();
            System.out.println("有人上线了：" + socket.getRemoteSocketAddress());
            //3.把这个客户端对应的socket通信管道，交给一个对立的线程负责处理
            new ServerReaderThread(socket).start();
        }
    }
}

服务线程类：

public class ServerReaderThread extends Thread {
    private Socket socket;

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

    @Override
    public void run() {
        try {
            OutputStream os = socket.getOutputStream();
            PrintStream ps = new PrintStream(os);
            ps.println("HTTP/1.1 200 OK");
            ps.println("Content-Type:text/html;charset=UTF-8");
            ps.println(); // 换行
            ps.println("<div style='color:red;front-size:120px;text-align:center'>黑马程序员666<div>");
            ps.close();
            socket.close();
        } catch (Exception e) {
        }
    }
}

 扩展知识：

每次请求都开一个新线程好吗？

答：不好，高并发时，容易宕机！

优化代码如下：

服务端

public class Server {
    public static void main(String[] args) throws Exception{
        System.out.println("服务端开启！");
        //1.创建ServerSocket的对象，同时为服务端注册端口。
        ServerSocket serverSocket = new ServerSocket(8080);

        //创建出一个线程池，负责处理通信管道的任务
        ThreadPoolExecutor pool = new ThreadPoolExecutor(16 * 2, 16 * 2,0, TimeUnit.SECONDS,
                new ArrayBlockingQueue<>(8), Executors.defaultThreadFactory(),
                new ThreadPoolExecutor.AbortPolicy());

        while (true) {
            //2.使用serverSocket对象，调用一个accept方法，等待客户端的连接请求
            Socket socket = serverSocket.accept();
            //3.把这个客户端对应的socket通信管道，交给一个对立的线程负责处理
            pool.execute(new ServerReaderRunnable(socket));
        }
    }
}

服务类线程池

public class ServerReaderRunnable implements Runnable {
    private Socket socket;

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

    @Override
    public void run() {
        try {
            OutputStream os = socket.getOutputStream();
            PrintStream ps = new PrintStream(os);
            ps.println("HTTP/1.1 200 OK");
            ps.println("Content-Type:text/html;charset=UTF-8");
            ps.println(); // 换行
            ps.println("<div style='color:red;front-size:120px;text-align:center'>黑马程序员666<div>");
            ps.close();
            socket.close();
        } catch (Exception e) {
        }
    }
}