我遇到的一个filter问题
filter代码如下：
package   util;

import   java.io.IOException;
import   javax.servlet.http.*;
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;

public   class   AdminFilter   extends   HttpServlet   implements   Filter  
{  
/**
  *  
  */
private   static   final   long   serialVersionUID   =   -5545950069282900798L;
protected   FilterConfig   filterConfig;
String   LOGIN_PAGE= "Login.jsp ";
public   void   doFilter(final   ServletRequest   req,   final   ServletResponse   res,final   FilterChain   chain)  
throws   IOException,   ServletException  
{
//   TODO   自动生成方法存根
HttpServletRequest   hreq=(HttpServletRequest)req;
HttpServletResponse   hres=(HttpServletResponse)res;
HttpSession   session=hreq.getSession();
String   flag= " ";
try
{
flag=(String)session.getAttribute( "isLogin ");
if( "true ".equals(flag))
{
chain.doFilter(hreq,   hres);
}
else
{
hres.sendRedirect(LOGIN_PAGE);
}
}
catch(Exception   e)
{
e.printStackTrace();
}
}

public   void   init(FilterConfig   config)   throws   ServletException  
{
//   TODO   自动生成方法存根
this.filterConfig=config;
}

public   void   setFilterConfig(FilterConfig   filterConfig)
{
this.filterConfig=filterConfig;
}

public   void   destroy()
{
this.filterConfig=null;
}

}


XML中配置如下：

    <servlet>
        <description> AdminFilter </description>
        <display-name> AdminFilter </display-name>
        <servlet-name> AdminFilter </servlet-name>
        <servlet-class> util.AdminFilter </servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name> AdminFilter </servlet-name>
        <url-pattern> /admin/* </url-pattern>
    </servlet-mapping>

我现在通过http://localhost/Infosite/Login.jsp登入到http://localhost/Infosite/admin/admin_.jsp，总是出现一下错误：

HTTP   Status   405   -   HTTP   method   GET   is   not   supported   by   this   URL

我尝试了/admin/下的其他页面登入，都出现相同错误。于是我将配置改成如下：

<servlet-mapping>
        <servlet-name> AdminFilter </servlet-name>
  &