项目实现要求

编写客户端和服务器代码，要求客户端和服务器进行对象的传输交流。
要求服务器支持同时多个客户端访问。
并且客户端能够使用多个账号进行登录。
客户端和服务器接收到对方的请求时，都给予对方响应内容。
密码输入错误后支持用户重新输入。

项目思考

首先要想去验证用户登录，就需要去构建一个用户类，这个用户类有账号和密码两个属性，为了方便验证登录效果（即比对账号和密码）还需要去重写equals方法。同时为了使得这个对象能够被序列化和反序列化，还需要去实现Serializable接口。
服务器想要支持多个客户端访问，就需要使用到多线程技术。
想要获取用户输入的账号和密码，还需要使用到Scanner类中的next()方法。
客户端想要实现多个账号进行登录，就需要提前将账号和密码信息填入到本地文件。

项目实现

本地账号文件user.txt。

zhangsan-123456
lisi-321654
wangwu-888888
zhaoliu-666666

用户类User：

package com.tipdm.demo7;

import java.io.Serializable;
import java.util.Objects;

public class User implements Serializable {
    private String userAccount;
    private String userPassword;

    public User() {
    }

    public User(String userAccount, String userPassword) {
        this.userAccount = userAccount;
        this.userPassword = userPassword;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        User user = (User) o;
        return Objects.equals(userAccount, user.userAccount) && Objects.equals(userPassword, user.userPassword);
    }

    @Override
    public int hashCode() {
        return Objects.hash(userAccount, userPassword);
    }

    @Override
    public String toString() {
        return "User{" +
                "userAccount='" + userAccount + '\'' +
                ", userPassword='" + userPassword + '\'' +
                '}';
    }

    public String getUserAccount() {
        return userAccount;
    }

    public void setUserAccount(String userAccount) {
        this.userAccount = userAccount;
    }

    public String getUserPassword() {
        return userPassword;
    }

    public void setUserPassword(String userPassword) {
        this.userPassword = userPassword;
    }
}

用户功能类UserService：

package com.tipdm.demo7;

import java.io.*;
import java.util.ArrayList;
import java.util.List;

public class UserService {
    public boolean checkLogin(User user){
        boolean login_flag = false;
        List<User> allUser = getAllUser();
        for (User currUser:
             allUser) {
            if (user.equals(currUser)){
                login_flag = true;
                break;
            }
        }
        return login_flag;
    }

    public List<User> getAllUser(){
        List <User> allUser = new ArrayList<>();
        File file = new File("day10-code\\user.txt");
        try {
            BufferedReader br = new BufferedReader(new FileReader(file));
            while (true){
                String str = br.readLine();
                if (str == null){
                    break;
                }
                String[] data = str.split("-");
                User user = new User(data[0], data[1]);
                allUser.add(user);
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
        return allUser;
    }
}

客户端类TestClient：

package com.tipdm.demo7;

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

public class TestClient {
    public static void main(String[] args) {
        while (true) {
            Scanner scanner = new Scanner(System.in);
            System.out.print("请输入用户名:");
            String account = scanner.next();
            System.out.print("请输入密码:");
            String password = scanner.next();
            User user = new User(account, password);

            try {
                Socket socket = new Socket("localhost", 7878);
                ObjectOutputStream oo = new ObjectOutputStream(socket.getOutputStream());
                oo.writeObject(user);
                oo.flush();
                socket.shutdownOutput();

                BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                String str = br.readLine();
                System.out.println("你好服务器，这里是客户端，我收到了你的响应信息。我登录请求状态是：" + str);
                br.close();
                socket.close();
                if (str.equals("true")){
                    System.out.println("登录成功！");
                    break;
                }
                System.out.println("===== 登录失败，请重新登录！=====");
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}

服务器线程类ServerThread：

package com.tipdm.demo7;

import java.io.BufferedWriter;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.OutputStreamWriter;
import java.net.Socket;

public class ServerThread extends Thread{
    private Socket socket;

    public ServerThread() {
    }

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

    @Override
    public void run() {
        try {
            ObjectInputStream oi = new ObjectInputStream(this.socket.getInputStream());
            User user = (User) oi.readObject();
            UserService us = new UserService();
            boolean login_glag = us.checkLogin(user);
            if (login_glag){
                System.out.println(user.getUserAccount() + "登录成功");
            }else {
                System.out.println(user.getUserAccount() + "登录失败");
            }
            this.socket.shutdownInput();
            BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(this.socket.getOutputStream()));
            bw.write("" + login_glag);
            bw.flush();
            bw.close();
            this.socket.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

服务器类TestServer：

package com.tipdm.demo7;

import java.net.ServerSocket;
import java.net.Socket;

public class TestServer {
    public static void main(String[] args) {
        System.out.println("====== 登录测试 =====");
        try {
            ServerSocket serverSocket = new ServerSocket(7878);
            while (true){
                Socket socket = serverSocket.accept();
                ServerThread serverThread = new ServerThread(socket);
                serverThread.start();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}