TCP协议的简单应用一

TCP协议的应用，实现一个服务器处理多个客户端请求（向服务器发送消息，服务器接收到后以原消息返回给客户端。）

客户端类

import java.io.*;
import java.net.Socket;
import java.util.Scanner;

//先写出后读入
public class EchoMultiClient {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);

        try {
            //创建一个Socket对象，指定要连接的服务器
            Socket socket = new Socket("127.0.0.1",6666);

            //向服务器发送数据，先从socket获得输出流，并包装
            PrintStream ps = new PrintStream(new BufferedOutputStream(socket.getOutputStream()));
            System.out.println("请输入要发送的内容：");
            String info = input.nextLine();
            ps.println(info);
            ps.flush();

            //读取服务器返回的消息，先从socket获得输入流，并包装
            BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            info = br.readLine();
            System.out.println(info);

            //关闭流
            br.close();
            ps.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

服务器类

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
* 处理多个客户端
* 主线程用于监听客户端的连接，每次有链接成功，开启一个线程来该客户端的消息
*/
public class EchoMultiServer {
    public static void main(String[] args) {

        //创建一个固定大小的线程池
        ExecutorService es = Executors.newFixedThreadPool(3);

        try {
            //创建服务器端套接字，并指定端口号
            ServerSocket serverSocket = new ServerSocket(6666);
            System.out.println("服务器已启动，等待连接。。");

            //现在不直接处理了，主线程只负责接待，具体操作交由其他线程实现
            while (true) {
                Socket socket = serverSocket.accept();
                System.out.println("一个客户端连接成功。。。" + socket.getInetAddress().getHostAddress());

                es.execute(new UserThread(socket));
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

/**
* 用来处理客户端请求的线程任务
*/
class UserThread implements Runnable {

    //处理谁？
    private Socket socket;

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

    @Override
    public void run() {
        try {
            //读取客户端请求
            BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            String info = br.readLine();
            System.out.println(info);

            //向客户端返回消息
            PrintStream ps = new PrintStream(new BufferedOutputStream(socket.getOutputStream()));
            ps.println("echo:" + info);
            ps.flush();

            ps.close();
            br.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}