<!-- 配置用于session验证的拦截器 -->

    <!--

        如果有多个拦截器满足拦截处理的要求，则依据配置的先后顺序来执行

     -->

    <mvc:interceptors>

        <mvc:interceptor>

            <!-- 拦截所有的请求，这个必须写在前面，也就是写在【不拦截】的上面 -->

            <mvc:mapping path="/**" />

            <!-- 但是排除下面这些，也就是不拦截请求 -->

            <mvc:exclude-mapping path="/login.html" />

            <mvc:exclude-mapping path="/account/login.do" />

            <mvc:exclude-mapping path="/account/regist.do" />

            <bean class="com.msym.cloudnote.interceptors.SessionInterceptor" />

        </mvc:interceptor>
        <!--可有多个mvc:interceptor-->

    </mvc:interceptors>

package com.msym.cloudnote.interceptors;

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;

/**

 * 判断是否登录的拦截器

 */

public class SessionInterceptor  implements HandlerInterceptor {

    @Override

    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,

            ModelAndView modelAndView) throws Exception {

    }

    @Override

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

            throws Exception {

    }

    @Override

    public boolean preHandle(HttpServletRequest req, HttpServletResponse res, Object handel) throws Exception {

        HttpSession session = req.getSession();

        // 从session当中获取特定的数据

        Object obj = session.getAttribute("userInfo");

        if (obj == null) {

            // 未登录，重定向到登录页面

            res.sendRedirect(req.getContextPath()+"/login.html");

            return false;

        }

        // 已登录，继续向后调用

        return true;

    }

}