把ApplicationResources.properties打进你的包packagename中,然后在web.xml中,加入以下内容:
<servlet>
    <servlet-name>action</servlet-name>
    <servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
    <!-- 这是你加入的内容 -->
    <init-param>
       <param-name>application</param-name>
       <param-value>packagename.ApplicationResources</param-value>
    </init-param>
    ......
</servlet>