tree其余代码均拷贝自org.jasig.cas.client.authentication.AuthenticationFilter-authentication.AuthenticationFilter

耶鲁大学开发的单点登录（Single Sign On）系统称为CAS（Central Authentication Service）被设计成一个独立的Web应用程序(cas.war)。它目前用几个Java Servlet作为实现并且通过一个Https服务器来运行。-Yale development of Single sign-on (use On) system is called the CAS (Central Authentication Service) is designed to