struts2中使用@InterceptorRef注解时报错,找不到自定义拦截器

-----------------------------struts.xml中的配置--------------------------------------
<struts>
<package name="crm" extends="struts-default" namespace="/">
<interceptors>
<interceptor name="userInterceptor" class="com.itheima.interceptor.UserInterceptor"/> <interceptor-stack name="myStack">
<interceptor-ref name="userInterceptor"/>
<interceptor-ref name="defaultStack"/>
</interceptor-stack>
</interceptors>
        </package>
</struts>
@Controller("visitAction")
@Scope("prototype")
@Namespace("/")
@ParentPackage("struts-default")
@InterceptorRef("myStack")
public class VisitAction extends BaseAction implements ModelDriven<Visit>{}
启动服务时报错:

Caused by: Unable to load configuration. - [unknown location]
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:70)
at org.apache.struts2.dispatcher.Dispatcher.getContainer(Dispatcher.java:967)
at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:435)
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:479)
... 14 more
Caused by: Unable to find interceptor class referenced by ref-name userInterceptor - [unknown location]