前面我们讲了基于UDP的网络编程

UDP回显服务器 

UDP字典服务器 

下面我们来讲基于TCP的回显服务编写

1、服务器

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;

public class Server {
    private static ServerSocket socket = null;

    public Server(int port) throws IOException {
        socket = new ServerSocket(port);
    }

    public static void start() throws IOException {
        System.out.println("服务器端启动！");
        //使用多线程的方式，可以与多个客户端连接
        while (true){
            Socket clientSocket = socket.accept();
            Thread thread = new Thread(()->{
                try {
                    procession(clientSocket);
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            });
            thread.start();
        }
    }

    public static void procession(Socket clientSocket) throws IOException {
        System.out.printf("[%s:%d] 客户端上线！",clientSocket.getInetAddress(),clientSocket.getPort());
        System.out.println();
        //TCP使用的是I/O流
        try (InputStream inputStream = clientSocket.getInputStream();
             OutputStream outputStream = clientSocket.getOutputStream();)
        {
            while (true){
                Scanner scanner = new Scanner(inputStream);
                if (!scanner.hasNext()){
                    System.out.printf("[%s:%d] 客户端下线",clientSocket.getInetAddress(),clientSocket.getPort());
                    System.out.println();
                    break;
                }
                String request = scanner.next();
                String response = process(request);

                PrintWriter writer = new PrintWriter(outputStream);
                writer.println(response);
                writer.flush();

                System.out.printf("[%s:%d] req:%s,resp:%s",clientSocket.getInetAddress().toString(),clientSocket.getPort(),request,response);
                System.out.println();
            }
        }catch (IOException e){
            e.printStackTrace();
        }finally {
            try {
                clientSocket.close();
            }catch (IOException e){
                e.printStackTrace();
            }
        }
    }

    public static String process(String request){
        return request;
    }

    public static void main(String[] args) throws IOException {
        Server server = new Server(9090);
        server.start();
    }
}

2、客户端

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;

public class Client {
    public static Socket socket = null;

    public Client(String ip,int port) throws IOException {
        socket = new Socket(ip,port);
    }

    public static void start() throws IOException {
        System.out.println("客户端启动！");
        Scanner scanner = new Scanner(System.in);
        try (InputStream inputStream = socket.getInputStream();
             OutputStream outputStream = socket.getOutputStream()){
            PrintWriter writer = new PrintWriter(outputStream);
            Scanner scannerRes = new Scanner(inputStream);
            while (true){
                System.out.print("->");
                String request = scanner.next();

                writer.println(request);
                writer.flush();

                String response = scannerRes.next();
                System.out.println(response);
            }
        }catch (IOException e){
            e.printStackTrace();
        }
    }


    public static void main(String[] args) throws IOException {
        Client client = new Client("127.0.0.1",9090);
        client.start();
    }

}

最终结果