CAS异常之context[]startup failed due to previous errors

localhost.log中报错的错误： 
java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory 

原因： 
缺少jar:commons-logging-1.1.jar 

解决办法： 
将commons-logging-1.1.jar拷贝到tomcat的lib目录下，重启tomcat，即可。