struts2 execAndWait拦截器空指针

程序运行数据量大速度慢，于是想做个loading页，配置了execAndWait这个拦截器之后，此Action下的所有方法都变成了空指针，请问为什么会这样，如何解决？具体如下：<action name="everydayStatisticsAction" class="everydayStatisticsAction">
         <interceptor-ref name="execAndWait">
         <param name="includeMethods">duanxin</param>
         </interceptor-ref>
         <result name="userStatistics">/statistics/everyday/userStatistic.jsp</result>
         <result name="mapStatistics">/statistics/everyday/duanxinStatistic.jsp</result>
         <result name="wait">/statistics/everyday/wait.jsp</result>
</action>
wait.jsp中加入了<meta http-equiv="refresh" content="10;url=<s:url includeParams='all'/>" />Action中实现了接口SessionAware，如
protected Map<String, Object> session;
public void setSession(Map<String, Object> session) {
        this.session = session;
    }