struts.xml中为什么加上<constant name="struts.devMode" value="true" />就出错

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:3800)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4450)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:791)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:771)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:526)
    at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:987)
    at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:909)
    at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:495)
    at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1206)
    at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:314)
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053)
    at org.apache.catalina.core.StandardHost.start(StandardHost.java:722)
    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:516)
    at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:583)
    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)
2010-3-1 22:26:44 org.apache.catalina.core.StandardContext start
严重: Error filterStart

　　

经诊断,此为struts2.1的bug,此为tomcat安装目录中有空格如：Tomcat 6.0,将目录重命名为Tomcat6即可。