启动cas server
启动客户端，访问url，org.jasig.cas.client.authentication.AuthenticationFilter.initInternal验证
cas server已经登陆时的流程
EncryptedCookieValueManager.obtainCookieValue(final Cookie cookie, final HttpServletRequest request) 获取cookie的值
CookieRetrievingCookieGenerator.retrieveCookieValue(final HttpServletRequest request) 检索cookie的值
ReflectionUtils.invokeMethod(Method method, @Nullable Object target, @Nullable Object... args)
GenericScope.invoke(MethodInvocation invocation)