Servlet.service() for servlet [jsp] in context with path [/struts2Study] threw exception
java.lang.IllegalStateException: Must have the StrutsPrepareFilter execute before this one
出现这个异常说明web.xml配置出现错误，说明没有 StrutsPrepareFilter过滤器，在web.xml中配置成org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter，而不是org.apache.struts2.dispatcher.ng.filter.StrutsExecuteFilter，