1、ActionServlet、ActionMapping、ActionForm、ActionForward

2、config = "/WEB-INF/struts-config.xml";

chainConfig = "org/apache/struts/chain/chain-config.xml";

configDigester = null;

convertNull = false;

internal = null;

internalName = "org.apache.struts.action.ActionResources";

registrations

servletMapping

servletName

3、ActionMapping继承至ActionConfig

ActionConfig ：exceptions、forwards、moduleConfig、attribute、actionId、inherit、cancellableSet、cancellable、extensionProcessed、forward、include、input、multipartClass、name、parameter、path、prefix、roles、roleNames、scope、suffix、type、unknown、validateSet、validate、command、catalog

4、ActionForm：servlet、multipartRequestHandler

5、ActionForward：inherit、extensionProcessed、name、path、module、redirect、command、catalog

6、ActionServlet继承至HttpServlet，处理execute里边有四个参数，最后两个是HttpServeltRequest，HttpServeltResonpse