[WARN] [Configuration] HttpFlexSession has not been registered as a listener in web.xml for this application so no events will be dispatched to FlexSessionAttributeListeners or FlexSessionBindingListeners. To correct this, register flex.messaging.HttpFlexSession as a listener in web.xml.
报这种错的原因是：项目里，BlazeDS的jar包缺少的问题。（我想，因为基本上不会犯低级错误——没有在web.xml里面配置HttpFlexSession listener吧！）
正确的BlazeDS的jar包是（5个！）：
