文件上传出现这样的错误提示Unable to load bean org.apache.struts2.dispatcher.multipart.MultiPartRequest (jakarta)

这个问题是在使用Struts2想做一个上传文件的页面时候Tomcat报出来的错误，详细信息如下：
2007-7-19 21:34:09 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet jsp threw exception
java.lang.RuntimeException: Unable to load bean org.apache.struts2.dispatcher.multipart.MultiPartRequest (jakarta) - [unknown location]
    at com.opensymphony.xwork2.inject.ContainerBuilder$4.create(ContainerBuilder.java:136)
    at com.opensymphony.xwork2.inject.ContainerImpl.getInstance(ContainerImpl.java:476)
    at com.opensymphony.xwork2.inject.ContainerImpl.getInstance(ContainerImpl.java:486)
    at com.opensymphony.xwork2.inject.ContainerImpl$9.call(ContainerImpl.java:517)
    at com.opensymphony.xwork2.inject.ContainerImpl.callInContext(ContainerImpl.java:542)
    at com.opensymphony.xwork2.inject.ContainerImpl.getInstance(ContainerImpl.java:515)
    at org.apache.struts2.dispatcher.Dispatcher.wrapRequest(Dispatcher.java:697)
    at org.apache.struts2.dispatcher.FilterDispatcher.prepareDispatcherAndWrapRequest(FilterDispatcher.java:330)
    at org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:390)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:210)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:174)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:151)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:870)
    at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
    at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
    at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
    at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:685)
    at java.lang.Thread.run(Thread.java:595)
Caused by: Unable to load bean org.apache.struts2.dispatcher.multipart.MultiPartRequest (jakarta) - [unknown location]
    at org.apache.struts2.config.BeanSelectionProvider$ObjectFactoryDelegateFactory.create(BeanSelectionProvider.java:246)
    at com.opensymphony.xwork2.inject.ContainerBuilder$4.create(ContainerBuilder.java:134)
    ... 22 more

最后Google了不少文章，找到了原因：（缺少了必要的jar包）

Struts2使用开源项目Apache Jakarta Commons FileUpload和内建的FileUploadInterceptor拦截器实现文件上传，所需的jar包如下：

commons-logging-1.1.jar
freemarker-2.3.8.jar
ognl-2.6.11.jar
struts2-core-2.0.6.jar
xwork-2.0.1.jar
commons-io-1.3.1.jar
commons-fileupload-1.2.jar

参考资料：

在Struts 2中实现文件上传

Struts2文件上传