JavaWeb 三层架构模拟登录登出实现案例 jsp

目录

一、架构图

二、目录结构

三、实现

（1）Dao层实现

（2）服务层处理业务

（3）控制器给视图返回数据

三、其他

一、架构图

二、目录结构

三、实现

（1）Dao层实现

数据库访问的基类：

package com.wxl.dao;


import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

//操作数据库的公共类
public class BaseDao {
    private static String driver;
    private static String url;
    private static String username;
    private static String password;

    //静态代码块，类加载的时候就初始化了
    static {
        Properties properties = new Properties();
        //通过类加载器读取对应的资源
        InputStream is = BaseDao.class.getClassLoader().getResourceAsStream("db.properties");

        try {
            properties.load(is);
        } catch (IOException e) {
            e.printStackTrace();
        }

        driver = properties.getProperty("driver");
        url = properties.getProperty("url");
        username = properties.getProperty("username");
        password = properties.getProperty("password");

    }

    //获取数据库的链接
    public static Connection getConnection() {
        Connection connection = null;
        try {
            Class.forName(driver);
            connection = DriverManager.getConnection(url, username, password);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
        return connection;
    }

    //编写查询公共类
    public static ResultSet execute(Connection connection, String sql, Object[] params, ResultSet resultSet, PreparedStatement preparedStatement) throws SQLException {
        //预编译的sql,在后面直接执行就可以了
        preparedStatement = connection.prepareStatement(sql);

        for (int i = 0; i < params.length; i++) {
            //setObject,占位符从1开始，但是我们的数组是从0开始！
            preparedStatement.setObject(i + 1, params[i]);
        }

        resultSet = preparedStatement.executeQuery();
        return resultSet;
    }

    //编写增删改公共方法
    public static int execute(Connection connection, String sql, Object[] params, PreparedStatement preparedStatement) throws SQLException {
        preparedStatement = connection.prepareStatement(sql);

        for (int i = 0; i < params.length; i++) {
            //setObject,占位符从1开始，但是我们的数组是从0开始！
            preparedStatement.setObject(i + 1, params[i]);
        }

        int updateRows = preparedStatement.executeUpdate(sql);
        return updateRows;
    }

    //释放资源
    public static boolean closeResource(Connection connection, PreparedStatement preparedStatement, ResultSet resultSet) {
        boolean flag = true;

        if (resultSet != null) {
            try {
                resultSet.close();
                resultSet = null;
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                flag = false;
            }
        }

        if (preparedStatement != null) {
            try {
                preparedStatement.close();
                preparedStatement = null;
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                flag = false;
            }
        }

        if (connection != null) {
            try {
                connection.close();
                connection = null;
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                flag = false;
            }
        }

        return flag;
    }
}

先创建dao的实现接口

package com.wxl.dao.user;

import com.wxl.model.User;

import java.sql.Connection;
import java.sql.SQLException;

public interface UserDao {

    //得到要登录的用户
    public User getLoginUser(Connection connection, String userCode) throws SQLException;

}

 实现类，查询数据库信息

package com.wxl.dao.user;

import com.wxl.dao.BaseDao;
import com.wxl.model.User;

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

public class UserDaoImpl implements UserDao {
    //得到要登录的用户
    public User getLoginUser(Connection connection, String userCode) throws SQLException {
        PreparedStatement pstm = null;
        ResultSet rs = null;
        User user = null;

        if (connection != null) {
            String sql = "select * from smbms_user where userCode=?";
            Object[] params = {userCode};
            rs = BaseDao.execute(connection, sql, params, rs, pstm);
            if (rs.next()) {
                user = new User();
                user.setId(rs.getInt("id"));
                user.setUserCode(rs.getString("userCode"));
                user.setUserName(rs.getString("userName"));
                user.setUserPassword(rs.getString("userPassword"));
                user.setGender(rs.getInt("gender"));
                user.setBirthday(rs.getDate("birthday"));
                user.setPhone(rs.getString("phone"));
                user.setAddress(rs.getString("address"));
                user.setUserRole(rs.getInt("userRole"));
                user.setCreatedBy(rs.getInt("createdBy"));
                user.setCreationDate(rs.getTimestamp("creationDate"));
                user.setModifyBy(rs.getInt("modifyBy"));
                user.setModifyDate(rs.getTimestamp("modifyDate"));
            }
            BaseDao.closeResource(null, pstm, rs);
        }
        return user;
    }

    //修改当前用户密码
    @Override
    public int updatePwd(Connection connection, int id, String password) throws SQLException {

        PreparedStatement pstm=null;
        int execute=0;
        if(connection!=null){
            String sql="update smbms_user set userPassword=? where id=?";
            Object params[]={password,id};
            execute=BaseDao.execute(connection,sql,params,pstm);
            BaseDao.closeResource(null,pstm,null);
        }
        return execute;
    }
}

（2）服务层处理业务

业务接口：

package com.wxl.service.user;

import com.wxl.model.User;

public interface UserService {

    //用户登录
    public User login(String userCode, String password);
}

实现业务的类：

package com.wxl.service.user;

import com.wxl.dao.BaseDao;
import com.wxl.dao.user.UserDao;
import com.wxl.dao.user.UserDaoImpl;
import com.wxl.model.User;

import java.sql.Connection;
import java.sql.SQLException;

public class UserServiceImpl implements UserService {

    //业务层都会调用dao层，所以我们要引入Dao层；
    private UserDao userDao;

    public UserServiceImpl() {
        userDao = new UserDaoImpl();
    }


    public User login(String userCode, String password) {
        Connection connection = null;
        User user = null;

        try {
            connection = BaseDao.getConnection();
            //通过业务层调用对应的具体的数据库操作
            user = userDao.getLoginUser(connection, userCode);
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            BaseDao.closeResource(connection, null, null);
        }

        if (user != null) {
            if (!password.equals(user.getUserPassword())) {
                user = new User();
            }
        }

        return user;
    }

}

（3）控制器给视图返回数据

登录

package com.wxl.controller.user;

import com.wxl.model.User;
import com.wxl.service.user.UserService;
import com.wxl.service.user.UserServiceImpl;
import com.wxl.util.Constants;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class LoginServlet extends HttpServlet {

    //Servlet:控制层，调用业务层代码

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        System.out.println("LoginServlet--start...");

        //获取用户名和密码
        String userCode = req.getParameter("userCode");
        String userPassword = req.getParameter("userPassword");

        //和数据库中的密码进行比对，调用业务层：
        UserService userService = new UserServiceImpl();
        User user = userService.login(userCode, userPassword);

        if (user != null) {//查有此人
            if (user.getUserPassword() != null) {//密码验证正确
                //将用户的信息放到Session中
                req.getSession().setAttribute(Constants.USER_SESSION, user);//这里已经把登录的人给查出来了
                //跳转到主页
                resp.sendRedirect("/jsp/frame.jsp");
            } else {//密码错误
                req.setAttribute("error", "密码错误");
                req.getRequestDispatcher("/login.jsp").forward(req, resp);
            }

        } else {//查无此人，无法登录
            //转发回登录页面，顺带提示它，用户名或者密码错误
            req.setAttribute("error", "用户名不存在");
            req.getRequestDispatcher("/login.jsp").forward(req, resp);
        }
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

登出

package com.wxl.controller.user;

import com.wxl.util.Constants;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class LogoutServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //移除用户的Constants.USER_SESSION
        req.getSession().removeAttribute(Constants.USER_SESSION);
        resp.sendRedirect("/login.jsp");//返回登录页面
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req,resp);
    }
}

三、其他

模型：

package com.wxl.model;

import java.util.Date;

public class User {
    private Integer id; //id
    private String userCode; //用户编码
    private String userName; //用户名称
    private String userPassword; //用户密码
    private Integer gender;  //性别
    private Date birthday;  //出生日期
    private String phone;   //电话
    private String address; //地址
    private Integer userRole;    //用户角色
    private Integer createdBy;   //创建者
    private Date creationDate; //创建时间
    private Integer modifyBy;     //更新者
    private Date modifyDate;   //更新时间

    private Integer age;//年龄
    private String userRoleName;    //用户角色名称


    public String getUserRoleName() {
        return userRoleName;
    }
    public void setUserRoleName(String userRoleName) {
        this.userRoleName = userRoleName;
    }
    public Integer getAge() {
        Date date = new Date();
        Integer age = date.getYear()-birthday.getYear();
        return age;
    }
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getUserCode() {
        return userCode;
    }
    public void setUserCode(String userCode) {
        this.userCode = userCode;
    }
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getUserPassword() {
        return userPassword;
    }
    public void setUserPassword(String userPassword) {
        this.userPassword = userPassword;
    }
    public Integer getGender() {
        return gender;
    }
    public void setGender(Integer gender) {
        this.gender = gender;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    public String getPhone() {
        return phone;
    }
    public void setPhone(String phone) {
        this.phone = phone;
    }
    public String getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }
    public Integer getUserRole() {
        return userRole;
    }
    public void setUserRole(Integer userRole) {
        this.userRole = userRole;
    }
    public Integer getCreatedBy() {
        return createdBy;
    }
    public void setCreatedBy(Integer createdBy) {
        this.createdBy = createdBy;
    }
    public Date getCreationDate() {
        return creationDate;
    }
    public void setCreationDate(Date creationDate) {
        this.creationDate = creationDate;
    }
    public Integer getModifyBy() {
        return modifyBy;
    }
    public void setModifyBy(Integer modifyBy) {
        this.modifyBy = modifyBy;
    }
    public Date getModifyDate() {
        return modifyDate;
    }
    public void setModifyDate(Date modifyDate) {
        this.modifyDate = modifyDate;
    }

}

页面访问限制过滤器：

package com.wxl.filter;

import com.wxl.model.User;
import com.wxl.util.Constants;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * author: Dragon Wu
 * date: 2022-01-22 18:42
 */
public class SysFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request=(HttpServletRequest) servletRequest;
        HttpServletResponse response=(HttpServletResponse) servletResponse;

        //过滤器，从Session中获取用户
        User user=(User) request.getSession().getAttribute(Constants.USER_SESSION);

        if(user==null){//已经被移除或注销了，或者未登录
            response.sendRedirect("/login.jsp");
        }else {
            filterChain.doFilter(request,response);
        }

    }

    @Override
    public void destroy() {

    }
}

web.xml配置：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
    <!--设置首页-->
    <welcome-file-list>
        <welcome-file>/login.jsp</welcome-file>
    </welcome-file-list>
    
    <servlet>
        <servlet-name>LoginServlet</servlet-name>
        <servlet-class>com.wxl.controller.user.LoginServlet</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>LogoutServlet</servlet-name>
        <servlet-class>com.wxl.controller.user.LogoutServlet</servlet-class>
    </servlet>
    
    
    <!--字符编码过滤器-->
    <filter>
        <filter-name>CharacterEncodingFilter</filter-name>
        <filter-class>com.wxl.filter.CharacterEncodingFilter</filter-class>
    </filter>
    <!--用户登录过滤器-->
    <filter>
        <filter-name>SysFilter</filter-name>
        <filter-class>com.wxl.filter.SysFilter</filter-class>
    </filter>

    <servlet-mapping>
        <servlet-name>LoginServlet</servlet-name>
        <url-pattern>/user/login.do</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>LogoutServlet</servlet-name>
        <url-pattern>/user/logout.do</url-pattern>
    </servlet-mapping>

    <filter-mapping>
        <filter-name>CharacterEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <filter-mapping>
        <filter-name>SysFilter</filter-name>
        <url-pattern>/jsp/*</url-pattern>
    </filter-mapping>

</web-app>

数据库信息配置：db.properties

driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/smbms?useUnicode=true&characterEncoding=utf-8
username=root
password=root

login.jsp:

<%@ page language="java" contentType="text/html; charset=UTF-8"
         pageEncoding="UTF-8" %>
<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title>系统登录 - 超市订单管理系统</title>
    <link type="text/css" rel="stylesheet" href="${pageContext.request.contextPath }/css/style.css"/>
    <script type="text/javascript">
        /* if(top.location!=self.location){
              top.location=self.location;
         } */
    </script>
<body class="login_bg">
<section class="loginBox">
    <header class="loginHeader">
        <h1>超市订单管理系统</h1>
    </header>
    <section class="loginCont">
        <form class="loginForm" action="${pageContext.request.contextPath}/user/login.do" name="actionForm"
              id="actionForm" method="post">
            <div class="info" style="position: relative;bottom: 20px;">${error}</div>
            <div class="inputbox">
                <label for="userCode">用户名：</label>
                <input type="text" class="input-text" id="userCode" name="userCode" placeholder="请输入用户名" required/>
            </div>
            <div class="inputbox">
                <label for="userPassword">密码：</label>
                <input type="password" id="userPassword" name="userPassword" placeholder="请输入密码" required/>
            </div>
            <div class="subBtn">
                <input type="submit" value="登录"/>
                <input type="reset" value="重置"/>
            </div>
        </form>
    </section>
</section>
</body>
</html>