SSO单点登录一：cas单点登录防止登出退出后刷新后退ticket失效报500错，也有退出后直接重新登录报票根验证错误

问题1： 我登录了client2，又登录了client3，现在我把client2退出了，在client3里面我F5刷新了一下，结果页面报错：

未能够识别出目标 'ST-41-2VcnVMguCDWJX5zHaaaD-cas01.example.org'票根

问题2：登录了client，然后退出，再重新输入用户名，结果页面也会报错 验证 'ST-41-2VcnVMguCDWJX5zHaaaD-cas01.example.org'失败

解决方法：自己测试了多遍并在网上做了参考后修改，最后验证成功，之后就不报错了。解决办法如下：

单点登出，客户端配置。我尝试使用SAML作为认证和Ticket校验，但是调试时发现单点登出取标识的方式只能识别CAS的认证和校验。
认证：org.jasig.cas.client.authentication.AuthenticationFilter
校验：org.jasig.cas.client.validation.Cas20ProxyReceivingTicketValidationFilter
过滤器顺序：
1. CAS Single Sign Out Filter
2. CAS Validation Filter
3. CAS Authentication Filter
4. CAS HttpServletRequest Wrapper Filter
5. CAS Assertion Thread Local Filter
特别注意Validation在Authentication之前，因为我使用的是Cas20ProxyReceivingTicketValidationFilter。

根据CAS文档描述：If you are using proxy validation, you should map the validation filter before the authentication filter.

  <!--   /****cas配置******/ -->

 <filter>
     <filter-name>characterEncodingFilter</filter-name>
     <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
     <init-param>
         <param-name>encoding</param-name>
         <param-value>UTF-8</param-value>
     </init-param>
 </filter>
 <filter-mapping>
     <filter-name>characterEncodingFilter</filter-name>
     <url-pattern>/*</url-pattern>
 </filter-mapping>
 <!-- 与CAS Single Sign Out Filter配合，注销登录信息 -->
 <listener>
 <listener-class>org.jasig.cas.client.session.SingleSignOutHttpSessionListener</listener-class>
 </listener>
 <!-- CAS Server 通知 CAS Client，删除session,注销登录信息 -->
 <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>

 <!-- CAS Client向CAS Server进行ticket验证 -->
 <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://cas.youjiao.tjxddfdfqjy.com/cas</param-value>
     </init-param>
     <init-param>
         <param-name>serverName</param-name>
         <param-value>http://xxpt.yodfdfujiao.tjxqjy.com</param-value>
     </init-param>
 </filter>

 <filter-mapping>
     <filter-name>CAS Validation Filter</filter-name>
     <url-pattern>/system/login/fm.jsp</url-pattern>
 </filter-mapping>

 <!-- 登录认证，未登录用户导向CAS Server进行认证 -->
 <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>http://cas.youjiao.tjxqjdcfdy.com/cas/login</param-value>
     </init-param>
     <init-param>
         <param-name>serverName</param-name>
         <param-value>http://xxpt.youdfdjiao.1tssjxqjy.com</param-value>
     </init-param>
 </filter>
 <filter-mapping>
     <filter-name>CAS Filter</filter-name>
     <url-pattern>/system/login/fm.jsp</url-pattern>
 </filter-mapping>

 <!-- 封装request, 支持getUserPrincipal等方法 -->
 <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>/*</url-pattern>
 </filter-mapping>
 <!-- 存放Assertion到ThreadLocal中 -->
 <filter>
     <filter-name>CAS Assertion Thread Local Filter</filter-name>
     <filter-class>org.jasig.cas.client.util.AssertionThreadLocalFilter</filter-class>
 </filter>
 <filter-mapping>
     <filter-name>CAS Assertion Thread Local Filter</filter-name>
     <url-pattern>/*</url-pattern>
 </filter-mapping>

这样配置以后基本就解决这个问题了。