严重: Exception starting filter struts2

错误代码：
2010-5-6 13:39:32 org.apache.catalina.core.AprLifecycleListener init
信息: The Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: E:\MyEclipse 7.5\Genuitec\Common\binary\com.sun.java.jdk.win32.x86_1.6.0.013\bin;E:\Tomcat 6.0\bin
2010-5-6 13:39:32 org.apache.coyote.http11.Http11Protocol init
信息: Initializing Coyote HTTP/1.1 on http-8080
2010-5-6 13:39:32 org.apache.catalina.startup.Catalina load
信息: Initialization processed in 516 ms
2010-5-6 13:39:32 org.apache.catalina.core.StandardService start
信息: Starting service Catalina
2010-5-6 13:39:32 org.apache.catalina.core.StandardEngine start
信息: Starting Servlet Engine: Apache Tomcat/6.0.10
2010-5-6 13:39:33 com.opensymphony.xwork2.util.logging.commons.CommonsLogger info
信息: Parsing configuration file [struts-default.xml]
2010-5-6 13:39:34 com.opensymphony.xwork2.util.logging.commons.CommonsLogger info
信息: Unable to locate configuration files of the name struts-plugin.xml, skipping
2010-5-6 13:39:34 com.opensymphony.xwork2.util.logging.commons.CommonsLogger info
信息: Parsing configuration file [struts-plugin.xml]
2010-5-6 13:39:34 com.opensymphony.xwork2.util.logging.commons.CommonsLogger info
信息: Parsing configuration file [struts.xml]
2010-5-6 13:39:34 com.opensymphony.xwork2.util.logging.commons.CommonsLogger info
信息: Overriding property struts.i18n.reload - old value: false new value: true
2010-5-6 13:39:34 com.opensymphony.xwork2.util.logging.commons.CommonsLogger info
信息: Overriding property struts.configuration.xml.reload - old value: false new value: true
2010-5-6 13:39:34 org.apache.catalina.core.StandardContext filterStart
严重: Exception starting filter struts2
java.lang.NullPointerException
at com.opensymphony.xwork2.util.FileManager$FileRevision.needsReloading(FileManager.java:209)
at com.opensymphony.xwork2.util.FileManager.fileNeedsReloading(FileManager.java:60)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.needsReload(XmlConfigurationProvider.java:325)
at org.apache.struts2.config.StrutsXmlConfigurationProvider.needsReload(StrutsXmlConfigurationProvider.java:168)
at com.opensymphony.xwork2.config.ConfigurationManager.conditionalReload(ConfigurationManager.java:220)
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:61)
at org.apache.struts2.dispatcher.Dispatcher.getContainer(Dispatcher.java:774)
at org.apache.struts2.dispatcher.ng.InitOperations.initStaticContentLoader(InitOperations.java:77)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.init(StrutsPrepareAndExecuteFilter.java:49)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:275)
at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:397)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:108)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:3693)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4342)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:761)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:741)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:525)
at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:920)
at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:883)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:492)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1138)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:311)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:120)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1023)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:719)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1015)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
at org.apache.catalina.core.StandardService.start(StandardService.java:448)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
at org.apache.catalina.startup.Catalina.start(Catalina.java:552)
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)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)
2010-5-6 13:39:34 org.apache.catalina.core.StandardContext start
严重: Error filterStart
2010-5-6 13:39:34 org.apache.catalina.core.StandardContext start
严重: Context [/Struts2_0100_Introduction] startup failed due to previous errors
2010-5-6 13:39:35 org.apache.coyote.http11.Http11Protocol start
信息: Starting Coyote HTTP/1.1 on http-8080
2010-5-6 13:39:35 org.apache.jk.common.ChannelSocket init
信息: JK: ajp13 listening on /0.0.0.0:8009
2010-5-6 13:39:35 org.apache.jk.server.JkMain start
信息: Jk running ID=0 time=0/16  config=null
2010-5-6 13:39:35 org.apache.catalina.startup.Catalina start
信息: Server startup in 2718 ms

解决方案：

将struts.xml文件中的这句<constant name="struts.devMode" value="true" />  value值改为false  意思是就是没次更改struts.xml文件后就必须重启tomcat不然更改就无效。改为true 就是更改struts.xml文件 tomcat不用重启 文件自动生效。