spring mvc 拦截器实现用户验证

1，spring mvc 基本配置

（1）web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>spring_mvc</display-name>
  <!-- 配置前端处理器 (即前端总控)-->
  <servlet>
    <servlet-name>springMvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <!-- 通过初始参数指定 Spring Mvc 配置文件路径-->
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:springMvc-Config.xml</param-value>
    </init-param>
    <!-- 指定当启动web项目时 ，创建出servlet对象-->
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>springMvc</servlet-name>
    <url-pattern>*.action</url-pattern>
  </servlet-mapping>
<web-app>

（2）配置springmvc-config.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:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd ">

  
  <!-- 开启组件扫描 ，扫描base-package扫描该包下及其子包的所有注解-->
  <context:component-scan base-package="com.mvc.controller"/>
  <!-- 默认配置适配器。映射器 -->
  <mvc:annotation-driven/>
  <!-- <bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter"/>
  <bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping"/> -->
  <!-- 配置视图映射 -->
  <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix" value="/jsp/"></property>
    <property name="suffix" value=".jsp"></property>
  </bean>
<beans>

2，正式开始实现用户验证

（1）创建user实体类

package com.mvc.bean;

public class User {
	private Integer id;//id
    private String username;//用户名
    private String password;//密码

    public Integer getId() {
        return id;
    }

    public void setId(Integer 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;
    }
}

（2）配置UserController 控制器

package com.mvc.controller;

import javax.servlet.http.HttpSession;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import com.mvc.bean.User;

@Controller
public class UserController {
    /**
     * 向用户登录页面跳转
     */
    @RequestMapping(value = "/login.action",method = RequestMethod.GET)
    public String toLogin(){
        return  "login";
    }

    /**
     * 用户登录
     */
    @RequestMapping(value = "/login.action",method = RequestMethod.POST)
    public String login(User user, Model model, HttpSession session){
        //获取用户名和密码
        String username=user.getUsername();
        String password=user.getPassword();
        //些处横板从数据库中获取对用户名和密码后进行判断
        if(username!=null&&username.equals("admin")&&password!=null&&password.equals("admin")){
            //将用户对象添加到Session中
            session.setAttribute("USER_SESSION",user);
            //重定向到主页面的跳转方法
            return "redirect:main.action";
        }
        model.addAttribute("msg","用户名或密码错误，请重新登录！");
        return "login";
    }

    @RequestMapping(value = "/main.action")
    public String toMain(){
        return "main";
    }
    
    @RequestMapping(value = "/logout.action")
    public String logout(HttpSession session){
        //清除session
        session.invalidate();
        //重定向到登录页面的跳转方法
        return "redirect:login.action";
    }
}

（3）编写拦截器

package com.mvc.interceptor;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import com.mvc.bean.User;

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

public class LoginInterceptor implements HandlerInterceptor {

    //处理前
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object o) throws Exception {
        //获取请求的RUi:去除http:localhost:8080这部分剩下的
        String uri = request.getRequestURI();
        //UTL:除了login.jsp是可以公开访问的，其他的URL都进行拦截控制
        if (uri.indexOf("/login") >= 0) {
            return true;
        }
        //获取session
        HttpSession session = request.getSession();
        User user = (User) session.getAttribute("USER_SESSION");
        //判断session中是否有用户数据，如果有，则返回true，继续向下执行
        if (user != null) {
            return true;
        }
        //不符合条件的给出提示信息，并转发到登录页面
        request.setAttribute("msg", "您还没有登录，请先登录！");
        request.getRequestDispatcher("/jsp/login.jsp").forward(request, response);
        return false;
    }

    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {

    }

    //完成之后
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {

    }
}

（4）在springmvc-config.xml配置拦截器

即在beans标签中加入以下代码

​
    <!--配置拦截器-->
    <mvc:interceptors>
        
        <!--登录拦截器-->
        <mvc:interceptor>
            <mvc:mapping path="/**"/>
            <bean class="com.mvc.interceptor.LoginInterceptor"/>
        </mvc:interceptor>
    </mvc:interceptors>

​

（5）编写login.jsp和main.jsp

login.jsp就是一个提交给login.action的一个表单，并且包含 ${msg}用来展示反馈信息，此处不贴代码

main.jsp可以随便是啥

（6）测试:未登录时直接访问main.action会服务器跳转到login.jsp表明用户验证拦截器配置成功。