未找到类: org/apache/commons/io/FileUtils和org.apache.commons.lang3.StringUtils

问题描述：
警告: Could not create JarEntryRevision for [jar:file:/D:/jbpmworkspaces/.metadata/.plugins/org.eclipse.wst.server.core/tmp0/wtpwebapps/ssh/WEB-INF/lib/struts2-core-2.3.15.jar]!
java.lang.NoClassDefFoundError: org/apache/commons/io/FileUtils
at com.opensymphony.xwork2.util.fs.JarEntryRevision.build(JarEntryRevision.java:50)
at com.opensymphony.xwork2.util.fs.DefaultFileManager.monitorFile(DefaultFileManager.java:97)
at com.opensymphony.xwork2.util.fs.DefaultFileManager.loadFile(DefaultFileManager.java:74)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadConfigurationFiles(XmlConfigurationProvider.java:1011)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadDocuments(XmlConfigurationProvider.java:165)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.init(XmlConfigurationProvider.java:132)
at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:225)
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:67)
at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:446)
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:490)
at org.apache.struts2.dispatcher.ng.InitOperations.initDispatcher(InitOperations.java:74)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.init(StrutsPrepareAndExecuteFilter.java:57)
at org.apache.catalina.core.ApplicationFilterConfig.initFilter(ApplicationFilterConfig.java:279)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:260)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:105)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4958)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5652)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1571)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1561)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.io.FileUtils
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1892)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1735)
... 24 more
解决办法：因为缺少commons-io、commons-lang或commons-lang3包，这两个jar包是干什么用的呢？为什么要在搭建矿建的时候引用呢？commons-io是处理IO的工具类包，对java.io进行扩展，提供了更加方便的IO操作；commons-lang是处理Java基本对象方法的工具类包，该类包提供对字符、数组等基本对象的操作，弥补了java.lang api基本处理方法上的不足。FileUtils在commons-io中，该类主要对文件进行操作，更加方便；StringUtils在commons-lang中，该类主要提供对字符串的操作,对null是安全的,主要提供了字符串查找,替换,分割,去空白,去掉非法字符等等操作。
解决了这个问题之后又报：java.lang.NoClassDefFoundError: org/apache/commons/fileupload/RequestContext错误，分析发现，自己少引用了Struts2.x中的不少包，找到并把相关的common包引用进来，能解决很多commons相关的异常，注意不要跟其他框架中有冲突就可以。相关commons的jar包如下图：