cas客户端报错
java.net.unknowhostexception:www.w3.org
这个错误

java.lang.NullPointerException
    at java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:768)
    at org.jasig.cas.client.proxy.ProxyGrantingTicketStorageImpl.retrieve(ProxyGrantingTicketStorageImpl.java:85)
    at org.jasig.cas.client.validation.Cas20ServiceTicketValidator.parseResponseFromServer(Cas20ServiceTicketValidator.java:91)
    at org.jasig.cas.client.validation.AbstractUrlBasedTicketValidator.validate(AbstractUrlBasedTicketValidator.java:217)
    at org.jasig.cas.client.validation.AbstractTicketValidationFilter.doFilter(AbstractTicketValidationFilter.java:169)
还有这个
谁遇到过啊
------解决方案--------------------
连不上外网
确定你的服务器能够访问http://www.w3.org/，是不是没配好dns之类的