struts2.0学习问题集锦at sun.jkernel.DownloadManager.getBootClassPathEntryForClass

严重: Null component Catalina:type=JspMonitor,name=jsp,WebModule=//localhost/StrutsTest,J2EEApplication=none,J2EEServer=none
2011-5-1 11:21:49 org.apache.catalina.startup.HostConfig checkResources
警告: Error during context [/StrutsTest] restart
java.lang.NullPointerException
at sun.jkernel.DownloadManager.getBootClassPathEntryForClass(DownloadManager.java:928)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:293)
at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1275)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1206)
at org.apache.catalina.startup.WebAnnotationSet.loadClassAnnotation(WebAnnotationSet.java:145)
at org.apache.catalina.startup.WebAnnotationSet.loadApplicationFilterAnnotations(WebAnnotationSet.java:84)
at org.apache.catalina.startup.WebAnnotationSet.loadApplicationAnnotations(WebAnnotationSet.java:57)
at org.apache.catalina.startup.ContextConfig.applicationAnnotationsConfig(ContextConfig.java:297)
at org.apache.catalina.startup.ContextConfig.start(ContextConfig.java:1064)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:261)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4252)
at org.apache.catalina.startup.HostConfig.checkResources(HostConfig.java:1114)
at org.apache.catalina.startup.HostConfig.check(HostConfig.java:1212)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:293)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)
at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1337)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1601)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1610)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1590)
at java.lang.Thread.run(Thread.java:619)

错误原因：web.xml配置文件错误，
原错误：<filter>
<filter-name>struts2</filter-name>
<filter_class>org.apache.struts2.dispatcher.FilterDispatcher</filter_class>
</filter>
修改： <filter>
<filter-name>struts2</filter-name>
<filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class>
</filter>