eclipse运行时tomcat报出下列的异常是什么原因

java.lang.ExceptionInInitializerError
at org.apache.catalina.startup.ContextConfig.createWebXmlDigester(ContextConfig.java:527)
at org.apache.catalina.startup.ContextConfig.init(ContextConfig.java:1015)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:276)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:142)
at org.apache.catalina.core.StandardContext.init(StandardContext.java:5703)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4453)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:799)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:779)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:583)
at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:675)
at org.apache.catalina.startup.HostConfig.deployDescriptors(HostConfig.java:601)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:502)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1317)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:324)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:142)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1065)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:822)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
at org.apache.catalina.core.StandardService.start(StandardService.java:525)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:754)
at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
Caused by: java.lang.NullPointerException
at org.apache.tomcat.util.descriptor.DigesterFactory.idFor(DigesterFactory.java:98)
at org.apache.tomcat.util.descriptor.DigesterFactory.(DigesterFactory.java:76)
... 28 more

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