MVC3中,怎么触发MvcHandler.ProcessRequest(HttpContextBase httpContext)方法

Question

Reflector查看MVC3,看到UrlRoutingModule的Init方法中调用的 PostResolveRequestCache方法中,

当IHttpHandler httpHandler = routeHandler.GetHttpHandler(requestContext);
获取完默认的MvcHandler后,下一步怎么触发MvcHandler.ProcessRequest(HttpContextBase httpContext)方法,求解! 谢谢