http://www.ibm.com/developerworks/cn/opensource/os-cn-cas/
http://steven-wiki.readthedocs.org/en/latest/security/cas-tomcat/#authenticationhanlder
http://blog.sina.com.cn/s/articlelist_1549622495_0_1.html
原文：http://www.cnblogs.com/tzhz/p/3532199.html