The struts dispatcher cannot be found

1、错误描述

     严重：Servlet.service() for servlet jsp threw exception

               The struts dispatcher cannot be found.This is usually called by using struts tags without

               the associated filters.Struts tags are only usable when the request has passed through its

               servlet filters,which initializes the struts dispatcher needed for this tag.-[unknown location]

2、错误原因

3、解决办法