今天看视频看到struts2中的配置文件中只要添加以下配置，那么以后修改配置文件不用重启tomcat的方法。于是自己手动试了试，没想到这一试竟然试出问题来

要添加的代码：

<constant name="struts.devMode" value="http://www.mamicode.com/true" />

struts.devMode也就是struts的开发模式，默认值为false，这里修改为true就可以了，以后一旦就该这个文件中的配置就不用去重启tomcat，着实方便许多。但是问题也出现了：

严重: Exception starting filter struts2java.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

经过google一搜，有说将<constant name="struts.devMode" value="http://www.mamicode.com/true" />中的值改为false的，我要的就是true，改成false不违背了我本意，后来经过多次查找发现有人说这个属于struts2.1的bug，tomcat目录不能有空格。我仔细一瞧我的tomcat路径，还真出现空格的。。。

最后通过自己修改路径发现此方法可行。

struts2出现at com.opensymphony.xwork2.util.FileManager$FileRevision.needsReloading(FileManager.java:20 .