Mr.张小白（案例：基于Spring MVC实现后台登陆系统验证）

基于Spring MVC实现后台登陆系统验证

一、步骤

1.引入相关依赖pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.zjd</groupId>
    <artifactId>chapter13</artifactId>
    <version>1.0-SNAPSHOT</version>

    <packaging>war</packaging>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.7</maven.compiler.source>
        <maven.compiler.target>1.7</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.8.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.2.8.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.1</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>
</project>

2.搭建Spring MVC环境（配置前端控制器）web.xml

<?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">
    <servlet>
        <servlet-name>DispatcherServlet</servlet-name>
        <servlet-class>
            org.springframework.web.servlet.DispatcherServlet
        </servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring-mvc.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>DispatcherServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

3.创建User类User.java

package com.zjd.pojo;
/*
* 用户类
* */
public class User {
    private String username;        //用户名
    private String password;        //用户密码

    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;
    }
}

4.创建User控制类UserController.java

package com.zjd.controller;

import com.zjd.pojo.User;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.servlet.http.HttpSession;

@Controller
public class UserController {
    //跳转到系统页面
    @RequestMapping("/main")
    public String toMainPage() {
        return "main";
    }
    //跳转到登陆页面
    @RequestMapping("/tologin")
    public String toLoginPage(){
        return "login";
    }
    //跳转到订单信息页面
    @RequestMapping("/orderinfo")
    public String orderinfo(){
        return "orderinfo";
    }
    /*
    * 用户登录
    * */
    @RequestMapping("/login")
    public String login(User user, Model model, HttpSession httpSession){
        //获取用户名和密码
        String username=user.getUsername();
        String password=user.getPassword();
        //此处模拟从数据库中获取用户名和密码后进行判断
        if (username!=null&&username.equals("zjd")&&password!=null&&password.equals("123")){
            //将用户添加到session
            httpSession.setAttribute("USER_SESSION",user);
            //用户登陆成功，转发到系统页面
            return "main";
        }
        //如果用户名和密码不匹配，转发到登陆页面，并进行提醒
        model.addAttribute("msg","用户名或密码错误，请重新登录");
        return "login";
    }
    /*
    * 用户退出
    * */
    @RequestMapping("/logout")
    public String logout(HttpSession httpSession){
        //清除session
        httpSession.invalidate();
        //退出登陆后重定向到登陆页面
        return "redirect:tologin";
    }
}

5.创建拦截器LoginInterceptor.java

package com.zjd.interceptor;

import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class LoginInterceptor extends HandlerInterceptorAdapter {
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response,Object handler) throws Exception{
        //获取请求的路径
        String uri=request.getRequestURI();
        //对用户登录的相关请求进行判断
        if (uri.indexOf("/login")>=0){
            return true;
        }
        HttpSession session=request.getSession();
        //如果用户是已登录状态，放行
        if (session.getAttribute("USER_SESSION")!=null){
            return true;
        }
        //其他情况都直接跳转到登陆页面
        request.setAttribute("msg","您还没有登录，请先登录！");
        request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request,response);
        return false;
    }
}

6.创建Spring MVC配置文件spring-mvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd  ">
    <!--    配置创建spring容器要扫描的包-->
    <context:component-scan base-package="com.zjd.controller"/>
    <!--    配置注解驱动-->
    <mvc:annotation-driven/>
    <!--    配置视图解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>
    <!--    配置拦截器-->
    <mvc:interceptors>
        <bean class="com.zjd.interceptor.LoginInterceptor"/>
    </mvc:interceptors>
    <!--    配置静态资源的访问映射，此配置中的文件将不被前端控制器拦截-->
    <mvc:resources mapping="/js/**" location="/js/"/>
</beans>

6.创建系统首页main.jsp

<%--
  Created by IntelliJ IDEA.
  User: 24360
  Date: 2022/11/27
  Time: 12:36
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>后台系统</title>
</head>
<body>
<li>您好：${USER_SESSION.username}</li>
<li><a href="${pageContext.request.contextPath}/logout">退出</a></li>
<li><a href="${pageContext.request.contextPath}/orderinfo">订单信息</a></li>

</body>
</html>

7.创建系统登录页login.jsp

<%--
  Created by IntelliJ IDEA.
  User: 24360
  Date: 2022/11/24
  Time: 21:00
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>用户登录</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/login" method="post">
    <div>${msg}</div>
    用户名：<input type="text" name="username"/><br/>
    密&nbsp;&nbsp;码：<input type="password" name="password"/><br/>
    <input type="submit" value="登录"/>
</form>
</body>
</html>

8.创建订单信息页面orderinfo.jsp

<%--
  Created by IntelliJ IDEA.
  User: 24360
  Date: 2022/11/24
  Time: 21:04
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>订单信息</title>
</head>
<body>
您好：${USER_SESSION.username}
<a href="${pageContext.request.contextPath}/logout">退出</a>
<table border="1" width="80%">
    <tr align="center"><td colspan="2">订单id：D001</td></tr>
    <tr align="center"><td>商品Id</td><td>商品名称</td></tr>
    <tr align="center"><td>P001</td><td>三文鱼</td></tr>
    <tr align="center"><td>P002</td><td>红牛</td></tr>
</table>
</body>
</html>

二、项目结构

三、本次完成案例：基于Spring MVC实现后台登陆系统验证

主要是对用户登陆状态的验证，只有登陆成功的用户才可以访问系统中的资源。

四、重要讯息！！！！！

各位小伙伴有疑问可以私聊我，我会在每周日统一查看回复

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五、下方评论区见该案例源代码

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