The workflow of strust2:
The client sends a request to the Tomcat container through HttpServletRequest ----> filter (core controller StrutsPrepareAndexecuteFiler) ---->
The core controller accesses ActionMapper to decide whether to call an action (if it is a jsp page, etc., the action will not be called) ------>
Core control ActionProxy (action proxy)---->ConfigurationManager (configuration manager) load struts.xml to find the action to be called--->
ActionProxy (action proxy) creates an instance of Action invocation ---> Calling the interceptor 123 ------ "The action is executed after the interceptor is executed.
Call the action business processing method and this method returns a string result ---> match the view according to the string ---> execute the interceptor in reverse order again 321
----Finally respond to the request through HttpServletRequest