webwork疑问请教?

Question

本人刚开始学webwork,做第一个示例就碰到一个问题,报错如下:java.lang.NoClassDefFoundError: com/uwyn/rife/continuations/ContinuationConfig
com.opensymphony.webwork.dispatcher.mapper.ActionMapperFactory.getMapper(ActionMapperFactory.java:31)
com.opensymphony.webwork.dispatcher.ServletDispatcher.service(ServletDispatcher.java:88)
javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
可我不知道com/uwyn/rife/continuations/ContinuationConfig这个Class是哪个jar包里面的,请教各位大侠,小弟先谢过了.