严重Exception starting filter struts2

严重: Exception starting filter struts2
java.lang.NullPointerException
    at com.opensymphony.xwork2.spring.SpringObjectFactory.getClassInstance(SpringObjectFactory.java:189)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.verifyResultType(XmlConfigurationProvider.java:479)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addResultTypes(XmlConfigurationProvider.java:450)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addPackage(XmlConfigurationProvider.java:407)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadPackages(XmlConfigurationProvider.java:239)
    at org.apache.struts2.config.StrutsXmlConfigurationProvider.loadPackages(StrutsXmlConfigurationProvider.java:111)
    at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reload(DefaultConfiguration.java:152)
    at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:52)
    at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:395)
    at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:452)
    at org.apache.struts2.dispatcher.FilterDispatcher.init(FilterDispatcher.java:201)
    at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:295)
    at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:422)
    at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:115)
    at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4072)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4726)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:799)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:779)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:601)
    at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1079)
    at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:1002)
    at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:506)
    at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1317)
    at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:324)
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:142)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1065)
    at org.apache.catalina.core.StandardHost.start(StandardHost.java:840)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057)
    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
    at org.apache.catalina.core.StandardService.start(StandardService.java:525)
    at org.apache.catalina.core.StandardServer.start(StandardServer.java:754)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)