java web 单点登录问题

如下是单点登录在web.xml中的配置，我的问题很简洁，就是，我请求的url是http://222.16.9.236:8080,直接跳转到登录页面，我的url不是以.action结尾的，为何也能被CAS Authentication Filter 这个过滤器过滤呢？哪位大神知道的，给小弟讲解下，不胜感激！
<!-- 单点登录 start-->
    <filter>
        <filter-name>CAS Single Sign Out Filter</filter-name>
        <filter-class>org.jasig.cas.client.session.SingleSignOutFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>CAS Single Sign Out Filter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <listener>
     <listener-class>org.jasig.cas.client.session.SingleSignOutHttpSessionListener</listener-class>
    </listener> 
    
<filter>
<filter-name>CAS Authentication Filter</filter-name>
<filter-class>org.jasig.cas.client.authentication.AuthenticationFilter</filter-class>
 
        <init-param>
            <param-name>casServerLoginUrl</param-name>
            <param-value>http://172.16.5.151:7103/sso/login</param-value>
        </init-param>
        <init-param>
            <param-name>renew</param-name>
            <param-value>false</param-value>
        </init-param>
        <init-param>
            <param-name>gateway</param-name>
            <param-value>false</param-value>
        </init-param>

        <init-param>
         <param-name>serverName</param-name>
         <param-value>http://127.0.0.1:8080</param-value>
        </init-param>
</filter>  

<filter>
<filter-name>CAS Validation Filter</filter-name>
<filter-class>org.jasig.cas.client.validation.Cas20ProxyReceivingTicketValidationFilter</filter-class>
        <init-param>
            <param-name>casServerUrlPrefix</param-name>
<param-value>http://172.16.5.151:7103/sso</param-value>
        </init-param>
       <init-param>
           <param-name>serverName</param-name>
           <param-value>http://127.0.0.1:8080</param-value>
 &nb