public class Server {

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

        //1、创建一个服务器端Socket，即ServerSocket，指定绑定的端口，并监听此端口

        ServerSocket serverSocket = new ServerSocket(10086);

        //2、调用accept()方法开始监听，等待客户端的连接

        Socket socket = serverSocket.accept();

        //3、获取输入流，并读取客户端信息

        InputStream is = socket.getInputStream();

        InputStreamReader isr = new InputStreamReader(is);

        BufferedReader br = new BufferedReader(isr);

        String info = null;

        //会阻塞知道客户端有数据过来

        while ((info = br.readLine()) != null) {

            System.out.println("我是服务器，客户端说：" + info);

        }

        socket.shutdownInput();//关闭输入流，不会关闭套接字

        //4、获取输出流，响应客户端的请求

        OutputStream os = socket.getOutputStream();

        PrintWriter pw = new PrintWriter(os);

        pw.write("欢迎您！");

        pw.flush();

        //5、关闭资源,会发送字符串到客户端

        pw.close();

        os.close();//会关闭套接字

        br.close();

        isr.close();

        is.close();

        socket.close();

        serverSocket.close();

    }

}

public class Client {

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

        //1、创建客户端Socket，指定服务器地址和端口

        Socket socket = new Socket("localhost", 10086); //这种方式会直接连接connect

        //2、获取输出流，向服务器端发送信息

        OutputStream os = socket.getOutputStream();//字节输出流

        PrintWriter pw = new PrintWriter(os);//将输出流包装成打印流

        pw.write("用户名：admin；密码：123");

        pw.flush();

        socket.shutdownOutput();//关闭输出流，会发送字符串到服务端，不会关闭套接字

        //3、获取输入流，并读取服务器端的响应信息

        InputStream is = socket.getInputStream();

        BufferedReader br = new BufferedReader(new InputStreamReader(is));

        String info = null;

        //会阻塞知道服务端有数据过来

        while ((info = br.readLine()) != null) {

            System.out.println("我是客户端，服务器说：" + info);

        }

        //4、关闭资源

        br.close();

        is.close();

        pw.close();

        os.close();//也会socket

        socket.close();

    }

}

socket != null && socket.isBound() && !socket.isClosed() && socket.isConnected()&& !socket.isInputShutdown() && !socket.isOutputShutdown()