纯struts2环境搭建

 <filter><!-- 核心控制器Fileter -->
  <filter-name>struts2</filter-name>
  <filter-class>
  org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter
  </filter-class>
  </filter>
  <filter-mapping>
  <filter-name>struts2</filter-name>
  <url-pattern>/*</url-pattern>
  </filter-mapping>

一下两个类都实现了filter类，都是struts的控制器

 <filter-class><!--
  org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter
  -->
  org.apache.struts2.dispatcher.FilterDispatcher
  </filter-class>

extends="struts-default" //默认的package继承