我不明白当我在 tomcat 中启动我的 web 服务时，有时会得到这个空指针异常。并且需要 3-4 次重新启动，然后这个异常就消失了。这是什么原因？我的堆栈跟踪是：
org.springframework.beans.factory.BeanDefinitionStoreException: Unexpected exception parsing XML document from ServletContext resource [/WEB-INF/Beans.xml]; nested exception is java.lang.NullPointerException
at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:412)
at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:334)
at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:302)
at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:143)
at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:178)
at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:149)
at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:124)
at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:93)
at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:130)
at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:467)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:397)
at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:282)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:204)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:47)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4323)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:4780)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:139)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:988)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:771)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:139)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:988)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:275)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:139)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:427)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:139)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:649)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:139)
at org.apache.catalina.startup.Catalina.start(Catalina.java:585)
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:288)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:415)
我的 xml 文件是：
<jaxrs:server id="restContainer" address="/" staticSubresourceResolution="true"> <jaxrs:serviceBeans>
<ref bean="FooBar" />
</jaxrs:serviceBeans>
<jaxrs:providers>
<bean class="org.apache.cxf.jaxrs.provider.JSONProvider">
<property name="dropRootElement" value="true" />
<property name="supportUnwrapped" value="true" />
</jaxrs:providers>
<camelcxf:rsServer id="rsServer" address="/" serviceClass="com.camel.example.FooBar" /> <camel:camelContext id="camelContext-1">
<camel:route>
<camel:from uri="cxfrs:bean:rsServer" />
<camel:to uri="http://localhost:8080/Google/rest/search" />
</camel:route>
</camel:camelContext>