我很好地在Eclipse中使用了Tomcat。现在，我无法启动服务器。尝试启动时出现以下异常。一切都很好。我不知道有什么改变，但是显然有些改变。

Apr 7, 2012 12:28:29 PM org.apache.catalina.core.StandardContext listenerStart
SEVERE: Exception sending context initialized event to listener instance of class org.apache.myfaces.webapp.StartupServletContextListener
java.lang.NoClassDefFoundError: org/apache/commons/digester/Digester
    at org.apache.myfaces.config.impl.digester.DigesterFacesConfigUnmarshallerImpl.<init>(DigesterFacesConfigUnmarshallerImpl.java:42)
    at org.apache.myfaces.config.FacesConfigurator.getUnmarshaller(FacesConfigurator.java:262)
    at org.apache.myfaces.config.FacesConfigurator.feedStandardConfig(FacesConfigurator.java:566)
    at org.apache.myfaces.config.FacesConfigurator.configure(FacesConfigurator.java:487)
    at org.apache.myfaces.webapp.AbstractFacesInitializer.buildConfiguration(AbstractFacesInitializer.java:296)
    at org.apache.myfaces.webapp.Jsp21FacesInitializer.initContainerIntegration(Jsp21FacesInitializer.java:73)
    at org.apache.myfaces.webapp.AbstractFacesInitializer.initFaces(AbstractFacesInitializer.java:118)
    at org.apache.myfaces.webapp.StartupServletContextListener.contextInitialized(StartupServletContextListener.java:111)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4779)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5273)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1566)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1556)
    at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
    at java.util.concurrent.FutureTask.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(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.digester.Digester
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1711)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1556)
    ... 18 more
Apr 7, 2012 12:28:29 PM org.apache.catalina.core.StandardContext startInternal
SEVERE: Error listenerStart
Apr 7, 2012 12:28:29 PM org.apache.catalina.core.StandardContext startInternal
SEVERE: Context [/webApp_appNameT] startup failed due to previous errors
Apr 7, 2012 12:28:29 PM org.apache.catalina.core.StandardContext listenerStop
SEVERE: Exception sending context destroyed event to listener instance of class org.apache.myfaces.webapp.StartupServletContextListener
java.lang.IllegalStateException: No Factories configured for this Application. This happens if the faces-initialization does not work at all - make sure that you properly include all configuration settings necessary for a basic faces application and that all the necessary libs are included. Also check the logging output of your web application and your container for any exceptions!
If you did that and find nothing, the mistake might be due to the fact that you use some special web-containers which do not support registering context-listeners via TLD files and a context listener is not setup in your web.xml.
A typical config looks like this;
<listener>
  <listener-class>org.apache.myfaces.webapp.StartupServletContextListener</listener-class>
</listener>

    at javax.faces.FactoryFinder.getFactory(FactoryFinder.java:172)
    at org.apache.myfaces.context.servlet.FacesContextImplBase.getApplication(FacesContextImplBase.java:131)
    at org.apache.myfaces.webapp.AbstractFacesInitializer._dispatchApplicationEvent(AbstractFacesInitializer.java:239)
    at org.apache.myfaces.webapp.AbstractFacesInitializer.destroyFaces(AbstractFacesInitializer.java:273)
    at org.apache.myfaces.webapp.StartupServletContextListener.contextDestroyed(StartupServletContextListener.java:153)
    at org.apache.catalina.core.StandardContext.listenerStop(StandardContext.java:4819)
    at org.apache.catalina.core.StandardContext.stopInternal(StandardContext.java:5466)
    at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:232)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:160)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1566)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1556)
    at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
    at java.util.concurrent.FutureTask.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Apr 7, 2012 12:28:29 PM org.apache.catalina.loader.WebappClassLoader checkThreadLocalMapForLeaks
SEVERE: The web application [/webApp_appNameT] created a ThreadLocal with key of type [java.lang.ThreadLocal] (value [java.lang.ThreadLocal@1d98a]) and a value of type [org.apache.myfaces.config.RuntimeConfig] (value [org.apache.myfaces.config.RuntimeConfig@1712651]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak.
Apr 7, 2012 12:28:29 PM org.apache.catalina.loader.WebappClassLoader checkThreadLocalMapForLeaks
SEVERE: The web application [/webApp_appNameT] created a ThreadLocal with key of type [java.lang.ThreadLocal] (value [java.lang.ThreadLocal@18aab40]) and a value of type [org.apache.myfaces.context.servlet.StartupFacesContextImpl] (value [org.apache.myfaces.context.servlet.StartupFacesContextImpl@f102d3]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak.
Apr 7, 2012 12:28:29 PM org.apache.catalina.loader.WebappClassLoader checkThreadLocalMapForLeaks
SEVERE: The web application [/webApp_appNameT] created a ThreadLocal with key of type [java.lang.ThreadLocal] (value [java.lang.ThreadLocal@f07355]) and a value of type [org.apache.myfaces.context.servlet.StartupFacesContextImpl] (value [org.apache.myfaces.context.servlet.StartupFacesContextImpl@23f1bb]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak.
Apr 7, 2012 12:28:29 PM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["http-bio-8080"]
Apr 7, 2012 12:28:29 PM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["ajp-bio-8009"]
Apr 7, 2012 12:28:29 PM org.apache.catalina.startup.Catalina start
INFO: Server startup in 1756 ms