If there is no problem with the annotation, I suggest you check it web.xml Configuration, I was sliding monitoring class introduction error, resulting in an error.
That’s right:

<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>

This is hand skating:

<listener>
    <listener-class>org.springframework.web.context.ContextLoader</listener-class>
  </listener>