JAVA高级面试进阶训练营视频教程

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今天在开发的过程中遇到一个错误与大家分享一下 :我遇到的错误是 java.lang.NoClassDefFoundError 这个错误的意思是什么了？没有找到定义的类的错误。与之相似的一个异常时java.lang.NotClassFound，这个异常表名没有找到类。马虎的开发人员可能会把 第一个错误当成第二个错误去处理，如果这样你就上当了。

• 先说一下java.lang.NotClassFound 与 java.lang.NoClassDefFoundError的区别：java.lang.NoClassDefFoundError 是unchecked Exception（也就是常说的运行时异常），java.lang.NotClassFound 是checkedException 对于这两种异常不熟悉的朋友请自行学习。
• java.lang.NotClassFound 造成的原因一般是缺少类文件，或者缺少jar造成的，解决方案是去查找异常指向的类，添加相应的jar或者类文件。
• java.lang.NoClassDefFoundError 产生的原因是 在类中有着静态的方法或者静态的方法块，去掉之后异常解除。具体原因有待分析

Caused by: java.lang.NoClassDefFoundError: Could not initialize class com.thinkgem.jeesite.common.sys.utils.UserUtils
    at com.thinkgem.jeesite.cms.service.CategoryServiceImpl.findByUser(CategoryServiceImpl.java:41)
    at com.thinkgem.jeesite.cms.service.CategoryServiceImpl$$FastClassBySpringCGLIB$$7d62ae78.invoke(<generated>)
    at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:708)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
    at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:98)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:262)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:95)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:644)
    at com.thinkgem.jeesite.cms.service.CategoryServiceImpl$$EnhancerBySpringCGLIB$$5b7c636a.findByUser(<generated>)
    at com.alibaba.dubbo.common.bytecode.Wrapper2.invokeMethod(Wrapper2.java)
    at com.alibaba.dubbo.rpc.proxy.javassist.JavassistProxyFactory$1.doInvoke(JavassistProxyFactory.java:46)
    at com.alibaba.dubbo.rpc.proxy.AbstractProxyInvoker.invoke(AbstractProxyInvoker.java:72)
    at com.alibaba.dubbo.rpc.protocol.InvokerWrapper.invoke(InvokerWrapper.java:53)
    at com.alibaba.dubbo.rpc.filter.ExceptionFilter.invoke(ExceptionFilter.java:64)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
    at com.alibaba.dubbo.rpc.filter.TimeoutFilter.invoke(TimeoutFilter.java:42)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
    at com.alibaba.dubbo.monitor.support.MonitorFilter.invoke(MonitorFilter.java:75)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
    at com.alibaba.dubbo.rpc.protocol.dubbo.filter.TraceFilter.invoke(TraceFilter.java:78)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
    at com.alibaba.dubbo.rpc.filter.ContextFilter.invoke(ContextFilter.java:60)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
    at com.alibaba.dubbo.rpc.filter.GenericFilter.invoke(GenericFilter.java:112)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
    at com.alibaba.dubbo.rpc.filter.ClassLoaderFilter.invoke(ClassLoaderFilter.java:38)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
    at com.alibaba.dubbo.rpc.filter.EchoFilter.invoke(EchoFilter.java:38)
    at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
    at com.alibaba.dubbo.rpc.protocol.dubbo.DubboProtocol$1.reply(DubboProtocol.java:108)
    at com.alibaba.dubbo.remoting.exchange.support.header.HeaderExchangeHandler.handleRequest(HeaderExchangeHandler.java:84)
    at com.alibaba.dubbo.remoting.exchange.support.header.HeaderExchangeHandler.received(HeaderExchangeHandler.java:170)
    at com.alibaba.dubbo.remoting.transport.DecodeHandler.received(DecodeHandler.java:52)
    at com.alibaba.dubbo.remoting.transport.dispatcher.ChannelEventRunnable.run(ChannelEventRunnable.java:82)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    ... 1 more