1、在springmvc-config.xml中添加一下配置

• 注意：这里拦截的是请求、而不是页面

   <!-- 配置拦截器 -->
   <mvc:interceptors>
     <mvc:interceptor>
         <mvc:mapping path="/user/*"/>
         <bean class="cn.com.Interceptor.MyInterceptor"></bean>
     </mvc:interceptor>
   </mvc:interceptors>
  

2、编写Interceptor、拦截相关请求

• 1、实现 HandlerInterceptor 接口

• 2、继承自HandlerInterceptorAdapter 抽象类

• 示例代码

        package cn.com.Interceptor;
        import javax.servlet.http.HttpServletRequest;
        import javax.servlet.http.HttpServletResponse;
        import org.springframework.web.servlet.HandlerInterceptor;
        import org.springframework.web.servlet.ModelAndView;
  
        public class MyInterceptor implements HandlerInterceptor{
  
            @Override
        public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3)
                throws Exception {
            // TODO Auto-generated method stub
  
        }
  
        @Override
        public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, ModelAndView arg3)
                throws Exception {
            // TODO Auto-generated method stub
  
        }
  
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object arg2) throws Exception {
            Object object = request.getSession().getAttribute("user");
            System.out.println("进入拦截器");
            if(object!=null){
                System.out.println("用户已登录");
                return true;            
            }
            System.out.println("非法访问");
            request.getRequestDispatcher("user/toLogin").forward(request, response);
            return false; //拦截
        }
  
    }