// 客户端

    public static void main(String[] args) {

        try (Scanner scan = new Scanner(System.in);

                Socket client = new Socket("127.0.0.1", 8484);

                PrintWriter writer = new PrintWriter(client.getOutputStream());

                BufferedReader reader = new BufferedReader(new InputStreamReader(client.getInputStream()));) {

            while (true) {

                // writer.print(scan.nextLine() + "\n");

                // Writer 的 write(scan.nextLine() + "\n");方法

                // 注意：由于服务器端是使用readLine，如果是用上面两种方式写入，必须加换行符，否则readLine是读取不到数据的

                writer.println(scan.nextLine());

                writer.flush();

                while (reader.ready()) {

                    System.out.println(reader.readLine());

                }

            }

        } catch (IOException e) {

            e.printStackTrace();

        }

    }

    // 服务端

    public static void main(String[] args) {

        try (Scanner scan = new Scanner(System.in);

                ServerSocket server = new ServerSocket(8484);

                Socket sc = server.accept();

                BufferedReader reader = new BufferedReader(new InputStreamReader(sc.getInputStream()));

                PrintWriter writer = new PrintWriter(sc.getOutputStream());) {

            while (true) {

                writer.println(scan.nextLine());

                writer.flush();

                while (reader.ready()) {

                    System.out.println(reader.readLine());

                }

            }

        } catch (Exception e) {

            e.printStackTrace();

        }

    }