【示例代码】Jquery仿WebQQ桌面程序特效~~附源码哦

实在是不好意思 跑这上面来问这种问题
只是我搞了好久
在网上也找了好久没找到解决的方法
还是得来啊
这是我的过滤器的代码

package com.yourcompany.tools;
import java.io.IOException;
import java.io.PrintWriter;
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.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class GuoLvQi  implements Filter {
/**
* Destruction of the servlet. <br>
*/
public void doFilter(ServletRequest request,
ServletResponse response,
FilterChain chain)throws ServletException, IOException
{
HttpServletRequest req = (HttpServletRequest)request;
HttpServletResponse res= (HttpServletResponse)response;
String uri=req.getContextPath()+"/form/renshi.jsp";
try{
if(req.getSession().getAttribute("用户名")==null)
res.sendRedirect(uri);
//req.getRequestDispatcher(uri).forward(req,response);
else
chain.doFilter(request, response);
}catch(Exception ex){ex.printStackTrace();}	}
public void destroy() {
// Just puts "destroy" string in log
// Put your code here

}
/**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {

}
public boolean test(int arg0) {
// TODO Auto-generated method stub
return false;
}
public void init(FilterConfig arg0) throws ServletException {
// TODO Auto-generated method stub
}
}

这下面是我的web.xml关于过滤器的配置

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.4" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee   http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <filter>
<filter-name>GuoLvQi</filter-name>
<filter-class>com.yourcompany.tools.GuoLvQi</filter-class>
</filter>
<filter-mapping>
<filter-name>GuoLvQi</filter-name>
<url-pattern>*.do</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>GuoLvQi</filter-name>
<url-pattern>*.jsp</url-pattern>
</filter-mapping>

我现在不想过滤器登录页面
如果过滤的话 那浏览器下面老是显示进入/form/renshi.jsp(登录页面)可老是进不去 就在那里打转
下面是我的过滤条件

if(req.getSession().getAttribute("用户名")==null)
res.sendRedirect(uri);

如果我把过滤条件注释的话

try{
//if(req.getSession().getAttribute("用户名")==null)
//res.sendRedirect(uri);
//req.getRequestDispatcher(uri).forward(req,response);
//else
chain.doFilter(request, response);
}catch(Exception ex){ex.printStackTrace();}

那么所有的页面都能进去了
请问怎么配置web.xml让它对登录页面不过滤呢
请大虾们帮我看下啊 谢谢！！！