[Java知识库]XZK-JAVA-支线任务-010605-MVC，登陆案例

?实体类对象，对象名和数据库表名相同，成员变量和数据库的数据字段名相同

package bean;

public class User {
    private int id;
    private String username;
    private String password;

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

?这里的接口为了让后端和数据库操作分离

package dao;

import bean.User;

public interface UserDao {
    /**
     * 获取数据库中的登陆信息
     * @param loginUser 后端给一个包含username和password的User
     * @return 数据库返回null则说明登陆信息有误，否则登陆成功
     */
    public User getLoginInformation(User loginUser);
}

?数据库的具体的操作逻辑，他继承了Druid数据库操作，也实现了上面的接口

package dao.impl;

import bean.User;
import dao.UserDao;
import util.DruidUtil;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class UserDaoImpl extends DruidUtil implements UserDao {
    User user = new User();
    Connection connection = null;
    PreparedStatement preparedStatement = null;
    ResultSet resultSet = null;
    @Override
    public User getLoginInformation(User loginUser) {
        try {
            connection = getConnection();
            preparedStatement = connection.prepareStatement("select * from user where username = ? and password = ?");
            preparedStatement.setString(1,loginUser.getUsername());
            preparedStatement.setString(2,loginUser.getPassword());
            resultSet = preparedStatement.executeQuery();
            while (resultSet.next()){
                user.setId(resultSet.getInt("id"));
                user.setUsername(resultSet.getString("username"));
                user.setPassword(resultSet.getString("password"));
            }
            return user;
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            close(resultSet,preparedStatement,connection);
        }
        return null;
    }
}

?

这里是一个接口，如果是前后端一起开发则直接根据接口，前端需要给后端什么数据，后端返回给前端的数据就确定了?

package service.impl;

import bean.User;
import dao.impl.UserDaoImpl;
import service.UserService;

public class UserServiceImpl implements UserService {

    @Override
    public User getUserDao(User loginUser) {
        User loginInformation = new UserDaoImpl().getLoginInformation(loginUser);
        return loginInformation;
    }
}

package servlet;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

/**
 * 登陆验证的过滤器
 */
@WebFilter("/*")
public class LoginFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws ServletException, IOException {
        //强制转换
        HttpServletRequest request1 = (HttpServletRequest) request;
        //1判断是否是登陆相关的资源：获取与登陆相关的资源路径
        String requestURI = request1.getRequestURI();
        //2判断是否包含登陆相关资源路径
        if (requestURI.contains("/login.jsp") || requestURI.contains("/UserServlet")){
            //包含，证明用户就是想登陆，放行
            chain.doFilter(request, response);
        }else {
            //不包含，需要验证用户是否登陆
            //3从session中获取user
            Object user = request1.getSession().getAttribute("user");
            if (user != null){
                //登陆了，放行
                chain.doFilter(request, response);
            }else {
                //没有登陆，跳转登陆页面
                request1.setAttribute("login_msg","您尚未登陆，请登录");
                request1.getRequestDispatcher("/login.jsp").forward(request1,response);
            }
        }
    }
    public void init(FilterConfig config) throws ServletException {
    }
    public void destroy() {
    }
}

package servlet;

import javax.servlet.annotation.WebListener;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

@WebListener
public class SessionListener implements HttpSessionListener {
    /**
     * session的创建
     * @param httpSessionEvent
     */
    @Override
    public void sessionCreated(HttpSessionEvent httpSessionEvent) {
        System.out.println("session创建");
    }

    /**
     * session的销毁
     * @param httpSessionEvent
     */
    @Override
    public void sessionDestroyed(HttpSessionEvent httpSessionEvent) {
        System.out.println("session销毁");
    }
}

package servlet;

import bean.User;
import com.mysql.cj.Session;
import service.impl.UserServiceImpl;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;

@WebServlet("/UserServlet")
public class UserServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        HttpSession session = request.getSession();
        request.setCharacterEncoding("utf-8");

        String username = request.getParameter("username");
        String password = request.getParameter("password");

        User loginUser = new User();
        loginUser.setUsername(username);
        loginUser.setPassword(password);

        UserServiceImpl userService = new UserServiceImpl();
        User userDao = userService.getUserDao(loginUser);

        if (userDao.getId() == 0){
            //登陆失败,

            //提示信息
            request.setAttribute("login_msg","登陆失败，请检查账号或密码");
            //转发到login.jsp页面
            request.getRequestDispatcher("/login.jsp").forward(request,response);
        }else {
            //登陆成功，
            //将用户存入session
            session.setAttribute("user",userDao);
            //跳转页面
            response.sendRedirect(request.getContextPath()+"/success.jsp");
        }
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }
}

测试类，测试一下，上面的数据库操作是否没有问题?

package test;

import bean.User;
import org.junit.Test;
import service.impl.UserServiceImpl;

public class UserTest {
    @Test
    public void userTest(){
        User loginUser = new User();
        loginUser.setUsername("superbaby");
        loginUser.setPassword("123");
        UserServiceImpl userService = new UserServiceImpl();
        User userDao = userService.getUserDao(loginUser);
        System.out.println(userDao);
        //User{id=1, username='superbaby', password='123'}
    }
}

德鲁伊的实现代码?

package util;

import com.alibaba.druid.pool.DruidDataSourceFactory;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

public class DruidUtil {
    private static DataSource dataSource;
    static {
        try {
            //加载配置文件
            Properties properties = new Properties();
            properties.load(DruidUtil.class.getClassLoader().getResourceAsStream("druid.properties"));
            //获取DataSource
            dataSource = DruidDataSourceFactory.createDataSource(properties);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**获取连接的方法
     * @return
     * @throws SQLException
     */
    public static Connection getConnection() throws SQLException {
        return dataSource.getConnection();
    }
    /**
     * 获取连接池的方法
     */
    public static DataSource getDataSource(){
        return dataSource;
    }
    /**
     *DQL查询
     * 释放资源
     */
    public static void close(ResultSet rs, Statement stmt, Connection conn){
        if (rs != null){
            try {
                rs.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        if (stmt != null){
            try {
                stmt.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        if (conn != null){
            try {
                conn.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
    }
    /**
     * DML增删改
     * 释放资源
     */
    public static void close(Statement stmt, Connection conn){
        DruidUtil.close(null,stmt,conn);
    }
}

?德鲁伊的配置文件

driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/day14
username=root
password=xxxx
#初始化连接数量
initialSize=5
#最大连接数
maxActive=10
#最大等待时间
maxWait=3000

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>$Title$</title>
  </head>
  <body>
  $END$
  </body>
</html>

登陆页面?

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>登陆</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/UserServlet" method="post">
    用户名：<input type="text" name="username"><br>
    密码：<input type="password" name="password"><br>
    <input type="submit" value="登陆">
</form>
<!-- 出错显示的信息框 -->
<div class="alert alert-warning alert-dismissible" role="alert">
    <button type="button" class="close" data-dismiss="alert">
        <span>&times;</span>
    </button>
    <strong>${login_msg}</strong>
</div>

</body>
</html>

?退出的逻辑实现

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<%
    session.removeAttribute("user");
    Object user = session.getAttribute("user");
    if (user == null){
        response.sendRedirect(request.getContextPath()+"/login.jsp");
    }
%>

</body>
</html>

?登陆成功页面

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>Title</title>
  </head>
  <body>
  <%User user = (User) session.getAttribute("user");
    response.getWriter().write("登陆成功！"+user.getUsername()+"欢迎您");%>
  <br>
  <a href="${pageContext.request.contextPath}/session.jsp">退出</a>
  </body>
</html>