spring的权限控制，过滤器

spring的过滤器可以实现登录状态问题

1.创建一个AccessFilter类，基础代码

package com.ujia.util.access;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;import com.ujia.entity.User;public class AccessFilter implements HandlerInterceptor {    @Override
    public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3) throws Exception {    }    @Override
    public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, ModelAndView arg3) throws Exception {    }    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //获取登录session
        User user=(User) request.getSession().getAttribute("user");
        //如果访问路径为登录首页，通过
        if(request.getRequestURI().startsWith(request.getContextPath()+"/user/login.htm")){
            return true;
        }
        //如果请求路径为登录,通过
        else if(request.getRequestURI().startsWith(request.getContextPath()+"/user/login")){
            return true;
        }
        //如果没有登录session，则返回到登录页面
        else if(null==user){
            response.sendRedirect(request.getContextPath()+"/user/login.htm");
            return false;
        }
        return true;
    }
}

springMVC配置

<!-- 过滤器 -->
        <mvc:interceptors>
            <bean class="com.ujia.util.access.AccessFilter"></bean>
        </mvc:interceptors>