导入的struts2的包：
commons-fileupload-1.2.2.jar
commons-io-2.0.1.jar
commons-logging-1.1.1.jar
ognl-3.0.4.jar
struts2-core-2.3.1.2.jar
xwork-core-2.3.1.2.jar
tomcat启动时的错误：
严重: Exception starting filter struts2
java.lang.NoClassDefFoundError: org/apache/commons/lang/StringUtils
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.register(XmlConfigurationProvider.java:201)
at org.apache.struts2.config.StrutsXmlConfigurationProvider.register(StrutsXmlConfigurationProvider.java:102)
at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:180)
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.ng.InitOperations.initDispatcher(InitOperations.java:69)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.init(StrutsPrepareAndExecuteFilter.java:51)
at org.apache.catalina.core.ApplicationFilterConfig.initFilter(ApplicationFilterConfig.java:277)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:258)
at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:382)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:103)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4638)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5294)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:895)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:871)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:615)
at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1095)
at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1617)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.lang.StringUtils
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1701)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1546)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
... 26 more
2012-3-21 23:02:10 org.apache.catalina.core.StandardContext startInternal
严重: Error filterStart
2012-3-21 23:02:10 org.apache.catalina.core.StandardContext startInternal
严重: Context [/struts22] startup failed due to previous errors
2012-3-21 23:02:10 org.apache.coyote.AbstractProtocol start
------解决方案--------------------
缺少commons-lang.jar
------解决方案--------------------
赞同楼上的推荐你struts的包直接拷贝！这样的不容易出错
------解决方案--------------------
缺少commons-lang.jar