struts2 的问题（tomcat启动报错），太搞人了
贴出具体情况，大家看有没碰到这种情况，
我只用到了struts2，使用到的jar包如下：
commons-logging-1.0.4.jar
freemarker-2.3.15.jar 
struts2-core-2.1.8.jar 
xwork-core-2.1.6.jar
commons-io-1.3.2.jar
commons-fileupload-1.2.1.jar
ognl-2.7.3.jar
启动tomcat报错，错误信息如下：
log4j:WARN No appenders could be found for logger (com.opensymphony.xwork2.config.providers.XmlConfigurationProvider).
log4j:WARN Please initialize the log4j system properly.
2010-11-3 14:48:46 org.apache.catalina.core.StandardContext filterStart
严重: Exception starting filter struts2
Class: com.opensymphony.xwork2.spring.SpringObjectFactory
File: SpringObjectFactory.java
Method: getClassInstance
Line: 209 - com/opensymphony/xwork2/spring/SpringObjectFactory.java:209:-1
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:431)
at org.apache.struts2.dispatcher.FilterDispatcher.init(FilterDispatcher.java:190)
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:3838)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4488)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:785)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
at org.apache.catalina.core.StandardService.start(StandardService.java:519)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
at org.apache.catalina.startup.Catalina.start(Catalina.java:581)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
Caused by: java.lang.NullPointerException
at com.opensymphony.xwork2.spring.SpringObjectFactory.getClassInstance(SpringObjectFactory.java:209)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.verifyResultType(XmlConfigurationProvider.java:519)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addResultTypes(XmlConfigurationProvider.java:490)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addPackage(XmlConfigurationProvider.java:446)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadPackages(XmlConfigurationProvider.java:264)
at org.apache.struts2.config.StrutsXmlConfigurationProvider.loadPackages(StrutsXmlConfigurationProvider.java:111)
at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:193)
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:55)
at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:374)
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:418)
... 19 more
2010-11-3 14:48:46 org.apache.catalina.core.StandardContext start
严重: Error filterStart
2010-11-3 14:48:46 org.apache.catalina.core.StandardContext start
严重: Context [/Others] startup failed due to previous errors

本人从网上搜到的主要说法
1.lib中多导入包的大原因：去掉struts2-spring-plugin-2.1.8包即可，因为没有用到spring。
2.还有的原因是用spring了，却没加监听器，在web.xml里面加上
跟本人情况不符
希望各位大哥帮忙解决，对症下药

------解决方案--------------------