Struts2 严重: Exception starting filter struts2 java.lang.NullPointerException

struts.xml

<constant name="struts.devMode" value="true" />

value值由false修改为true

restart tomcat 报错如下：

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:3709)

    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4363)

    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:525)

    at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:926)

    at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:889)

    at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:492)

    at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1149)

    at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:311)

    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)

    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053)

    at org.apache.catalina.core.StandardHost.start(StandardHost.java:719)

    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:578)

    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)

2012-4-16 17:09:31 org.apache.catalina.core.StandardContext start

严重: Error filterStart

2012-4-16 17:09:31 org.apache.catalina.core.StandardContext start

严重: Context [/Struts2_0100_Introduction] startup failed due to previous errors

2012-4-16 17:09:31 org.apache.coyote.http11.Http11Protocol start

信息: Starting Coyote HTTP/1.1 on http-8080

2012-4-16 17:09:31 org.apache.jk.common.ChannelSocket init

信息: JK: ajp13 listening on /0.0.0.0:8009

2012-4-16 17:09:31 org.apache.jk.server.JkMain start

信息: Jk running ID=0 time=0/15  config=null

2012-4-16 17:09:31 org.apache.catalina.startup.Catalina start

信息: Server startup in 1941 ms

引起这个问题的原因是tomcat的安装路径中包含空格。