session超时或用户没有登陆时跳转到指定页面

用户登陆时把用户名放在session里面(也可以放别的)

   session.setAttribute("username",username);

做一个过滤器进行过滤

import javax.servlet.*;   
import javax.servlet.http.HttpServletRequest;   
import javax.servlet.http.HttpServletResponse;   
import javax.servlet.http.HttpSession;     
import java.io.IOException;   
  
/**  
 * 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   
 implements Filter   
{   
  
  
 public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException   
 {   
  HttpServletRequest request = (HttpServletRequest) servletRequest;   
  HttpServletResponse response = (HttpServletResponse) servletResponse;   
  
   HttpSession session = request.getSession(); 
   //用户超时或没有登陆时跳转到登陆页面
   if(session.Attribute("username")==null||session.isnew())
   {
     response.sendRedirect("登陆页面");
   }

   
  filterChain.doFilter(servletRequest, servletResponse);   
 }   
  
 public void destroy()   
 {   
 
 }   
  
  
 public void init(FilterConfig filterConfig) throws ServletException   
 {   

   
 }   
}  

在web.xml文件中进行配置

  <filter>
        <filter-name>..<filter-name>
        <filter-class>..<filter-class>
   <filter>
      
    <filter-mapping>
       <filter-name>..<filter-name>
       <url-pattern>...<url-pattern>

     <filter-mapping>

   <session-config>
        <!-- 以分钟为单位 -->
        <session-timeout>15</session-timeout>
    </session-config>

评论

1 楼 andey007518 2009-11-09  

只是大体示范了大体的写法，首先谢谢了，不过你看，session.Attribute("username")==nul，这样判断的话，项目启动后会一直进行循环的，造成死循环的，