Session超时跳转到指定页面（filter实现）解决了图片被过滤问题_session超时filter

package com.myplan.checkloginfilter;
 
import javax.servlet.*;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.io.PrintWriter;
 
/**   
 * 用于检测用户是否登陆的过滤器，如果未登录或超时，则重定向到指的登录页面<p>     
 */
public class CheckLoginFilter extends HttpServlet implements Filter {
 
    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain filterChain) {
        try {
            HttpServletRequest hsr = (HttpServletRequest) request;
            HttpSession session = hsr.getSession();
            if (hsr.getRequestURI().startsWith(
                    hsr.getContextPath() + "/login.jsp")
                    || hsr.getRequestURI().startsWith(
                            hsr.getContextPath() + "/login.do")
                    || hsr.getRequestURI().equals(hsr.getContextPath() + "/")
                    ) {
                // 请求登陆页面，所以放过  
                System.out.println("放过login");
                filterChain.doFilter(request, response);
            } else {
                if (session.getAttribute("employeeEmail") != null) {
                    //这里session存在，那么则登陆，放过session  
                    // 已登录，放过请求  
                    System.out.println("test filter chain");
                    filterChain.doFilter(request, response);
                } else {
                    //session超期后，自然session就是空了，那么则跳转到指定的页面就可以了  
                    // 未登录，跳转到登录页  
                    
                    PrintWriter out = response.getWriter();
                    out.print("<script>window.top.location.href='http://blog.163.com/girl_lihuiyue@126/blog/"
                            + hsr.getContextPath() + "';</script>");
                }
            }
        } catch (ServletException sx) {
        } catch (IOException iox) {
        }
    }
 
    public void destroy() {
 
    }
 
    public void init(FilterConfig filterConfig) throws ServletException {
 
    }
}

使用filter导致跳转到登陆页面的图片不显示。添加红色字体部分，跳过图片的过滤。

web.xml相应的配置

<filter> 
      <filter-name>CheckLoginFilter</filter-name> 
      <filter-class>com.myplan.checkloginfilter.CheckLoginFilter</filter-class> 
 </filter> 
  <filter-mapping> 
     <filter-name>CheckLoginFilter</filter-name> 
     <url-pattern>*.jsp</url-pattern>
   </filter-mapping> 
<span style="color:#FF0000;">如果使用session的话，配置
 <session-config> 
      <!-- 以分钟为单位 --> 
      <session-timeout>30</session-timeout> 
  </session-config></span>