请教各位大哥大姐一下这个是什么问题
严重: Exception starting filter struts2
java.lang.NoClassDefFoundError: org/apache/commons/lang/StringUtils
at com.opensymphony.xwork2.config.providers.XmlHelper.getLoadOrder(XmlHelper.java:117)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider$1.compare(XmlConfigurationProvider.java:965)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider$1.compare(XmlConfigurationProvider.java:963)
at java.util.Arrays.mergeSort(Arrays.java:1270)
at java.util.Arrays.sort(Arrays.java:1210)
at java.util.Collections.sort(Collections.java:159)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadConfigurationFiles(XmlConfigurationProvider.java:963)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadDocuments(XmlConfigurationProvider.java:155)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.init(XmlConfigurationProvider.java:122)
at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:179)
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:66)
at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:390)
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:436)
at org.apache.struts2.dispatcher.FilterDispatcher.init(FilterDispatcher.java:195)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:295)
at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:422)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:115)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4038)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4692)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:799)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:779)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:546)
at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1041)
at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:964)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:502)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1277)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:321)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:142)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1061)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:785)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
at org.apache.catalina.core.StandardService.start(StandardService.java:525)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:701)
at org.apache.catalina.startup.Catalina.start(Catalina.java:585)
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:289)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.lang.StringUtils
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1647)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1493)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
... 41 more
2012-1-13 23:07:11 org.apache.catalina.core.StandardContext start