SpringMVC之拦截器的的配置和使用

拦截器与过滤器的区别：拦截器只能拦截controller的请求，过滤器可以过滤所有请求

（1）实现HandlerInterceptor接口

　　　在执行控制器中的方法之前执行preHandle（）中的方法

 package com.eu.weh.web;

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

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

 import com.eu.weh.bean.User;

 /**
  *
  * @ClassName: LoginInterceptor
  * @Description: 登录拦截器
  * @author Administrator
  * @date 2019年4月29日 上午10:31:25
  *
  */
 public class LoginInterceptor implements HandlerInterceptor {

     public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
             throws Exception {

         //判断当前用户是否已经登录
         HttpSession session = request.getSession();
         User loginUser = (User) session.getAttribute("dbUser");
         if (loginUser == null) {
             String path = session.getServletContext().getContextPath();
             response.sendRedirect(path+"/login");
             return false;
         }else {
             return true;
         }
     }

     public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
             ModelAndView modelAndView) throws Exception {

     }

     public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
             throws Exception {

     }

 }

（2）SpringMVC配置文件

 <mvc:interceptors>
         <mvc:interceptor>
             <mvc:mapping path="/**" />
             <mvc:exclude-mapping path="/login" />
             <mvc:exclude-mapping path="/doAJAXlogin" />
             <mvc:exclude-mapping path="/bootstrap/**" />
             <mvc:exclude-mapping path="/css/**" />
             <mvc:exclude-mapping path="/fonts/**" />
             <mvc:exclude-mapping path="/img/**" />
             <mvc:exclude-mapping path="/jquery/**" />
             <mvc:exclude-mapping path="/layer/**" />
             <mvc:exclude-mapping path="/script/**" />
             <mvc:exclude-mapping path="/ztree/**" />
             <bean class="com.eu.weh.web.LoginInterceptor"></bean>
         </mvc:interceptor>
     </mvc:interceptors>