求助！运行一个用ssh框架做的网站报错！

错误代码如下：
2013-12-11 17:08:00 org.apache.catalina.startup.HostConfig checkResources
信息: Reloading context [/mydang]
log4j:WARN No appenders could be found for logger (com.opensymphony.xwork2.config.providers.XmlConfigurationProvider).
log4j:WARN Please initialize the log4j system properly.
2013-12-11 17:08:00 org.apache.catalina.core.StandardContext filterStart
严重: Exception starting filter struts2
Unable to load configuration. - [unknown location]
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:431)
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:277)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:258)
at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:382)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:103)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4624)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5281)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.startup.HostConfig.checkResources(HostConfig.java:1362)
at org.apache.catalina.startup.HostConfig.check(HostConfig.java:1450)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:295)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1338)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1496)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1506)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1485)
at java.lang.Thread.run(Thread.java:619)
Caused by: Unable to load configuration. - [unknown location]
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:58)
at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:374)
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:418)
... 19 more
Caused by: Caught exception while loading file struts-default.xml - [unknown location]
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadConfigurationFiles(XmlConfigurationProvider.java:902)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadDocuments(XmlConfigurationProvider.java:143)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.init(XmlConfigurationProvider.java:110)
at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:168)
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:55)
... 21 more
Caused by: java.lang.ClassCastException: org.apache.xerces.parsers.XML11Configuration cannot be cast to org.apache.xerces.xni.parser.XMLParserConfiguration
at org.apache.xerces.parsers.DOMParser.<init>(Unknown Source)
at org.apache.xerces.parsers.DOMParser.<init>(Unknown Source)
at org.apache.xerces.jaxp.DocumentBuilderImpl.<init>(Unknown Source)
at org.apache.xerces.jaxp.DocumentBuilderFactoryImpl.newDocumentBuilder(Unknown Source)
at com.sun.org.apache.xalan.internal.xsltc.trax.SAX2DOM.<init>(SAX2DOM.java:69)
at com.sun.org.apache.xalan.internal.xsltc.runtime.output.TransletOutputHandlerFactory.getSerializationHandler(TransletOutputHandlerFactory.java:187)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.getOutputHandler(TransformerImpl.java:392)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerHandlerImpl.setResult(TransformerHandlerImpl.java:137)
at com.opensymphony.xwork2.util.DomHelper$DOMBuilder.setup(DomHelper.java:205)
at com.opensymphony.xwork2.util.DomHelper$DOMBuilder.<init>(DomHelper.java:190)
at com.opensymphony.xwork2.util.DomHelper$DOMBuilder.<init>(DomHelper.java:181)
at com.opensymphony.xwork2.util.DomHelper$DOMBuilder.<init>(DomHelper.java:167)
at com.opensymphony.xwork2.util.DomHelper.parse(DomHelper.java:107)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadConfigurationFiles(XmlConfigurationProvider.java:893)
... 25 more
2013-12-11 17:08:00 org.apache.catalina.core.StandardContext startInternal
严重: Error filterStart
2013-12-11 17:08:00 org.apache.catalina.core.StandardContext startInternal
严重: Context [/mydang] startup failed due to previous errors
希望高手能帮我看下是怎么回事？谢谢！ --------------------编程问答-------------------- struts.xml
配置错误。
贴一下看看哪里错了 --------------------编程问答-------------------- Caused by: Caught exception while loading file struts-default.xml - [unknown location]
楼上说的对，仔细检查一下 --------------------编程问答-------------------- --------------------编程问答-------------------- <?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.1.7//EN"
"http://struts.apache.org/dtds/struts-2.1.7.dtd">
<struts>
<include file="struts-user.xml"></include>
<include file="struts-main.xml"></include>
<include file="struts-cart.xml"></include>
<include file="struts-order.xml"></include>
<package name="dangdang-default" namespace="/" extends="struts-default.xml">
<interceptors>
<interceptor name="checklogin"
class="org.tarena.dang.common.CheckLoginInterceptor"></interceptor>
<interceptor-stack name="loginStack">
<interceptor-ref name="checklogin"></interceptor-ref>
<interceptor-ref name="defaultStack"></interceptor-ref>
</interceptor-stack>
</interceptors>
<global-results>
<result name="login">/user/login_form.jsp</result>
</global-results>
</package>
</struts>
这是我配置的struts.xml --------------------编程问答-------------------- 十几天了，才贴上

你不会这个问题还在吧 --------------------编程问答-------------------- 是的呢一直还没解决呢！
--------------------编程问答-------------------- 顶一下~!顶一下~!顶一下~! --------------------编程问答-------------------- extends="struts-default.xml"> =====>extends="struts-default"> --------------------编程问答-------------------- extends="struts-default.xml"> =====>extends="struts-default">
这个不是问题的关键啊？

补充：Java ,  Web 开发