今天做了個Struts2.0 + tiles的實例，結果在啓動tomcat的時候，老是報錯：
2009-12-3 2:06:06 org.apache.catalina.core.StandardContext listenerStart
嚴重: Exception sending context initialized event to listener instance of class org.apache.struts2.tiles.StrutsTilesListener
java.lang.NoClassDefFoundError: org/apache/commons/collections/ArrayStack
at org.apache.commons.digester.Digester.<init>(Digester.java:142)
at org.apache.tiles.definition.digester.DigesterDefinitionsReader.<init>(DigesterDefinitionsReader.java:188)
at org.apache.tiles.definition.UrlDefinitionsFactory.init(UrlDefinitionsFactory.java:118)
at org.apache.tiles.impl.BasicTilesContainer.initializeDefinitionsFactory(BasicTilesContainer.java:185)
at org.apache.tiles.impl.BasicTilesContainer.init(BasicTilesContainer.java:121)
at org.apache.tiles.factory.TilesContainerFactory.initializeContainer(TilesContainerFactory.java:232)
at org.apache.tiles.factory.TilesContainerFactory.createTilesContainer(TilesContainerFactory.java:198)
at org.apache.tiles.factory.TilesContainerFactory.createContainer(TilesContainerFactory.java:163)
at org.apache.tiles.web.startup.TilesListener.createContainer(TilesListener.java:90)
at org.apache.struts2.tiles.StrutsTilesListener.createContainer(StrutsTilesListener.java:66)
at org.apache.tiles.web.startup.TilesListener.contextInitialized(TilesListener.java:57)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3764)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4216)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:760)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:740)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:544)
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:1022)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:736)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1014)
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:700)
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:585)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:295)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:433)
2009-12-3 2:06:06 org.apache.catalina.core.StandardContext start
嚴重: Error listenerStart
2009-12-3 2:06:06 org.apache.catalina.core.StandardContext start
嚴重: Context [/struts2.0] startup failed due to previous errors
2009-12-3 2:06:06 org.apache.tiles.access.TilesAccess setContainer
信息: Removing TilesContext for context: org.apache.catalina.core.ApplicationContextFacade
2009-12-3 2:06:06 org.apache.tiles.impl.BasicTilesContainer init
信息: Initializing Tiles2 container. . .
2009-12-3 2:06:06 org.apache.tiles.impl.BasicTilesContainer initializeDefinitionsFactory
信息: Tiles2 container initialization complete.
2009-12-3 2:06:06 org.apache.tiles.access.TilesAccess setContainer
信息: Publishing TilesContext for context: org.apache.catalina.core.ApplicationContextFacade
2009-12-3 2:06:06 com.opensymphony.xwork2.config.providers.XmlConfigurationProvider register
信息: Parsing configuration file [struts-default.xml]
2009-12-3 2:06:06 com.opensymphony.xwork2.config.providers.XmlConfigurationProvider register
信息: Parsing configuration file [struts-plugin.xml]
2009-12-3 2:06:06 com.opensymphony.xwork2.config.providers.XmlConfigurationProvider register
信息: Parsing configuration file [struts.xml]
2009-12-3 2:06:06 org.apache.struts2.config.Settings getLocale
警告: Settings: Could not parse struts.locale setting, substituting default VM locale
2009-12-3 2:06:07 com.opensymphony.xwork2.util.ObjectTypeDeterminerFactory <clinit>
信息: Setting DefaultObjectTypeDeterminer as default ...
2009-12-3 2:06:07 org.apache.coyote.http11.Http11BaseProtocol start
信息: Starting Coyote HTTP/1.1 on http-6866
2009-12-3 2:06:07 org.apache.jk.common.ChannelSocket init
信息: JK: ajp13 listening on /0.0.0.0:8009
2009-12-3 2:06:07 org.apache.jk.server.JkMain start
信息: Jk running ID=0 time=0/15 config=null
2009-12-3 2:06:07 org.apache.catalina.storeconfig.StoreLoader load
信息: Find registry server-registry.xml at classpath resource
2009-12-3 2:06:07 org.apache.catalina.startup.Catalina start
信息: Server startup in 2484 ms
查了半天，終於功夫不負苦心人，原來是commons-beanutils-1.6.0.jar的問題，升級到commons-beanutils-1.7.0.jar，問題迎刃而解！