@WebServlet("/login")
public class LoginServlet extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        // 根据用户数据库验证用户名和密码
        if (isValidUser(username, password)) {
            //登陆成功
            request.getSession().setAttribute("username", username);
            response.sendRedirect("dashboard.jsp"); // Redirect to the dashboard or another secure page
        } else {
            // 登录失败
            response.sendRedirect("login.jsp?error=true");
        }
    }

    private boolean isValidUser(String username, String password) {
        // 实现逻辑来验证用户(例如，检查数据库）
        // 如果用户有效则返回true，否则返回false
        //这是一个基本示例
        return "demo".equals(username) && "password123".equals(password);
    }
}
@WebServlet("/logout")
public class LogoutServlet extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 使会话失效以注销用户
        request.getSession().invalidate();
        response.sendRedirect("login.jsp");
    }
}
@WebServlet("/dashboard")
public class DashboardServlet extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 检查用户是否通过认证
        if (request.getSession().getAttribute("username") == null) {
            response.sendRedirect("login.jsp");
            return;
        }

        // 显示仪表板
        // 您的安全页面逻辑在这里
        response.getWriter().println("Welcome to the dashboard, " + request.getSession().getAttribute("username"));
    }
}
@WebServlet("/dashboard")
public class DashboardServlet extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 检查用户是否通过认证
        if (request.getSession().getAttribute("username") == null) {
            response.sendRedirect("login.jsp");
            return;
        }

        // 显示仪表板
        // 安全页面逻辑在这里
        response.getWriter().println("Welcome to the dashboard, " + request.getSession().getAttribute("username"));
    }
}

//1、添加MyBatis和MySQL JDBC驱动的依赖：
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.5.7</version>
</dependency>

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.27</version>
</dependency>

    //配置MyBatis的SQL映射文件（user_mapper.xml）：
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="UserMapper">

  <select id="getAllUsers" resultType="User">
    SELECT * FROM users
  </select>
</mapper>

    //创建User类和UserMapper接口：
public class User {
    private int id;
    private String username;
    private String email;
    private String password_hash;
    private String role;
    private Date created_at;
    private Date updated_at;

    // Getters and setters
}

public interface UserMapper {
    List<User> getAllUsers();
}

//2、配置MyBatis的数据库连接信息和映射文件路径：
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;

public class MyBatisConfig {

    private static SqlSessionFactory sqlSessionFactory;

    static {
        try {
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static SqlSessionFactory getSqlSessionFactory() {
        return sqlSessionFactory;
    }
}

//3、创建一个Java类来执行查询：
import org.apache.ibatis.session.SqlSession;

import java.util.List;

public class Main {
    public static void main(String[] args) {
        SqlSession sqlSession = MyBatisConfig.getSqlSessionFactory().openSession();
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        List<User> users = userMapper.getAllUsers();
        for (User user : users) {
            System.out.println("id: " + user.getId());//用户的唯一标识符，通常是自增的。
            System.out.println("username: " + user.getUsername());//用户的用户名，必须是唯一的。
            System.out.println("email: " + user.getEmail());//用户的电子邮件地址，也必须是唯一的。
            System.out.println("password_hash: " + user.getPassword_hash());//用户的密码哈希值，
            System.out.println("role: " + user.getRole());//用户的角色，通常用于区分不同用户的权限。
            System.out.println("created_at: " + user.getCreated_at());//用户的创建时间，记录用户账户的创建时间。
            System.out.println("updated_at: " + user.getUpdated_at());//用户的更新时间，记录用户账户的最后更新时间。
        }
        sqlSession.close();
    }
}