java.lang.NoClassDefFoundError: org/apache/commons/io/output/NullOutputStream

java.lang.NoClassDefFoundError: org/apache/commons/io/output/NullOutputStream

 Could not create JarEntryRevision for [jar:file:/E:/JAVA/Tarena-FTP/apache-tomcat-6.0.30-win/apache-tomcat-6.0.30/webapps/demo03/WEB-INFb/struts2-core-2.2.1.jar]!
java.lang.NoClassDefFoundError: org/apache/commons/io/output/NullOutputStream
at com.opensymphony.xwork2.util.FileManager$JarEntryRevision.build(FileManager.java:307)
at com.opensymphony.xwork2.util.FileManager.loadFile(FileManager.java:145)
at com.opensymphony.xwork2.util.FileManager.loadFile(FileManager.java:105)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadConfigurationFiles(XmlConfigurationProvider.java:898)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadDocuments(XmlConfigurationProvider.java:154)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.init(XmlConfigurationProvider.java:121)
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:371)
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:415)
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.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.io.output.NullOutputStream
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)
... 39 more

  在开发项目demo04时,每次启动Tomcat都会报上面的错误,仔细核对要导jar包有

                                                                                                                                           发现该导的都导了,但还是报错,而且运行该工程又没错误,实在令人费解,

暮然回首那人却在灯火南山处:原来报的错误是demo03!!!!!!!!!

所以说我们在做项目的时候不光光要关注当前的项目,也许是老项目在被加载时报的错,谨记!!!