刚学struts2，总是报错Caused by Action class not found
小弟初学struts2，按书上写了个程序但是运行总是报错。。Caused by Action class not found，但是我按着ctrl点击struts.xml中zhang.LoginAction也能定位到LoginAction类，研究了一天还是没有找到原因，特来求教


三月 01, 2014 11:34:32 下午 org.apache.struts2.dispatcher.Dispatcher error
SEVERE: Dispatcher initialization failed
Unable to load configuration. - action - file:/D:/workspace/.metadata/.plugins/org.eclipse.wst.server.core/tmp0/wtpwebapps/StrutsTestDemo/WEB-INF/classes/struts.xml:12:50
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:70)
at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:445)
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:489)
at org.apache.struts2.dispatcher.FilterDispatcher.init(FilterDispatcher.java:193)
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:4809)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5485)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
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 [zhang.LoginAction] not found - action - file:/D:/workspace/.metadata/.plugins/org.eclipse.wst.server.core/tmp0/wtpwebapps/StrutsTestDemo/WEB-INF/classes/struts.xml:12:50
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.verifyAction(XmlConfigurationProvider.java:482)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addAction(XmlConfigurationProvider.java:426)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.addPackage(XmlConfigurationProvider.java:552)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadPackages(XmlConfigurationProvider.java:292)
at org.apache.struts2.config.StrutsXmlConfigurationProvider.loadPackages(StrutsXmlConfigurationProvider.java:112)
at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:258)
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:67)
... 15 more


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struts.xml
<?xml version="1.0" encoding="GBK"?>
<!DOCTYPE struts PUBLIC  
    "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"  
    "http://struts.apache.org/dtds/struts-2.0.dtd">  
<struts>
<!-- 指定全局国际化资源文件base名 -->
<constant name="struts.custom.i18n.resources" value="messageResource"/>
<!-- 指定国际化编码所使用的字符集 -->
<constant name="struts.i18n.en