eclipse配置Struts2的问题，class文件在哪儿

我把struts例子中的class文件复制到classes目录下action能够执行，把class文件删掉不能执行，在action中class=“…………”的位置是正确的，按住ctrl能够进去，就是不能生成class文件，启动tomcat的时候提示重大: Dispatcher initialization failed
Unable to load configuration. - action - file:/D:/workspace/Struts2_0200/WebRoot/WEB-INF/classes/example.xml:10:56
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:69)
at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:380)
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:424)
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:273)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:254)
at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:372)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:98)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4584)
at org.apache.catalina.core.StandardContext$2.call(StandardContext.java:5262)
at org.apache.catalina.core.StandardContext$2.call(StandardContext.java:5257)
at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
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: Action class [example.HelloWorld] not found - action - file:/D:/workspace/Struts2_0200/WebRoot/WEB-INF/classes/example.xml:10:56
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.verifyAction(XmlConfigurationProvider.java:420)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addAction(XmlConfigurationProvider.java:365)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addPackage(XmlConfigurationProvider.java:479)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.reloadRequiredPackages(XmlConfigurationProvider.java:301)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadPackages(XmlConfigurationProvider.java:286)
at org.apache.struts2.config.StrutsXmlConfigurationProvider.loadPackages(StrutsXmlConfigurationProvider.java:111)
at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:204)
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:66)
... 16 more9 28, 2011 2:05:17 午後 org.apache.catalina.core.StandardContext filterStart
重大: フィルタ struts2 の起動中の例外です
Unable to load configuration. - action - file:/D:/workspace/Struts2_0200/WebRoot/WEB-INF/classes/example.xml:10:56
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:437)
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:273)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:254)
at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:372)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:98)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4584)
at org.apache.catalina.core.StandardContext$2.call(StandardContext.java:5262)
at org.apache.catalina.core.StandardContext$2.call(StandardContext.java:5257)
at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
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: Unable to load configuration. - action - file:/D:/workspace/Struts2_0200/WebRoot/WEB-INF/classes/example.xml:10:56
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:69)
at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:380)
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:424)
... 14 more
Caused by: Action class [example.HelloWorld] not found - action - file:/D:/workspace/Struts2_0200/WebRoot/WEB-INF/classes/example.xml:10:56
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.verifyAction(XmlConfigurationProvider.java:420)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addAction(XmlConfigurationProvider.java:365)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addPackage(XmlConfigurationProvider.java:479)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.reloadRequiredPackages(XmlConfigurationProvider.java:301)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadPackages(XmlConfigurationProvider.java:286)
at org.apache.struts2.config.StrutsXmlConfigurationProvider.loadPackages(StrutsXmlConfigurationProvider.java:111)
at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:204)
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:66)
... 16 more这是什么问题啊，已经调了一天了