cas客户端不能部署成功 出现404
需要说明的是在加上cas配置前http://localhost:18080/examples/servlets/servlet/HelloWorldExample
这样是可以出现heoolword界面的，但是在web.xml中加上下面的配置后就是404了，没有任何日志信息


<!-- ======================== 单点登录开始 ======================== -->
<!-- 用于单点退出，该过滤器用于实现单点登出功能，可选配置-->
<listener>
<listener-class>org.jasig.cas.client.session.SingleSignOutHttpSessionListener</listener-class>
</listener>

<!-- 该过滤器用于实现单点登出功能，可选配置。 -->
<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>/servlet/*</url-pattern>
</filter-mapping>

<filter>
<filter-name>CAS Filter</filter-name>
<filter-class>org.jasig.cas.client.authentication.AuthenticationFilter</filter-class>
<init-param>
<param-name>casServerLoginUrl</param-name>
<param-value>https://localhost:8443/cas/login</param-value>
</init-param>
<init-param>
<param-name>serverName</param-name>
<param-value>http://localhost:18080</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>CAS Filter</filter-name>
<url-pattern>/servlet/*</url-pattern>
</filter-mapping>
<!-- 该过滤器负责对Ticket的校验工作，必须启用它 -->
<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>https://localhost:8443/cas</param-value>
</init-param>
<init-param>
<param-name>serverName</param-name>
<param-value>http://localhost:18080</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>CAS Validation Filter</filter-name>
<url-pattern>/servlet/*</url-pattern>
</filter-mapping>

<!--
该过滤器负责实现HttpServletRequest请求的包裹，
比如允许开发者通过HttpServletRequest的getRemoteUser()方法获得SSO登录用户的登录名，可选配置。
-->
<filter>
<filter-name>CAS HttpServletRequest Wrapper Filter</filter-name>
<filter-class>
org.jasig.cas.client.util.HttpServletRequestWrapperFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>CAS HttpServletRequest Wrapper Filter</filter-name>
<url-pattern>/servlet/*</url-pattern>
</filter-mapping>

    <!--
该过滤器使得开发者可以通过org.jasig.cas.client.util.AssertionHolder来获取用户的登录名。
比如AssertionHolder.getAssertion().getPrincipal().getName()。
-->
<filter>
<filter-name>CAS Assertion Thread Local Filter</filter-name>
<filter-class>org.jasig.cas.client.util.AssertionThreadLocalFilter</filter-class>
</filter>
<filter-mapping&