过滤器 登录时seesion为空返回登录页

package com.spider.reader.common.filter;

 

import java.io.IOException;

 

import javax.servlet.Filter;

import javax.servlet.FilterChain;

import javax.servlet.FilterConfig;

import javax.servlet.ServletException;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

 

public class SecurityFilter implements Filter {

 

public void destroy() {

// TODO Auto-generated method stub

 

}

 

public void doFilter(ServletRequest request, ServletResponse response,

            FilterChain chain) throws IOException, ServletException {

        //Session属于HTTP范畴，所以ServletRequest对象需要先转换成HttpServletRequest对象

        HttpServletRequest req=(HttpServletRequest)request;

        HttpServletResponse res=(HttpServletResponse)response;

        //取得请求的URL

        String url = req.getRequestURL().toString();

        if(url.indexOf("login.action")!=-1 || url.indexOf("loginOut.action")!=-1 ){

        //过滤器放行ation

        }else{

        if(req.getSession() == null || req.getSession().getAttribute("loginname") == null){

                  res.sendRedirect(req.getContextPath()+"/login.action");  //跳回登录页

        }

        }

        chain.doFilter(request, response);

}

 

public void init(FilterConfig arg0) throws ServletException {

// TODO Auto-generated method stub

 

}

 

}

 

web.xml配置

          <filter>

<filter-name>sercurity</filter-name>

<filter-class>

com.spider.reader.common.filter.SecurityFilter

</filter-class>

          </filter>

          <filter-mapping>

<filter-name>sercurity</filter-name>

<url-pattern>*.action</url-pattern>

          </filter-mapping>