FAQ（48）：java.lang.NoClassDefFoundError: Could not initialize class com.smbms.controller.IndexControl

2018/1/5

看Log：

exception
javax.servlet.ServletException: Servlet.init() for servlet springmvc threw exception
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:504)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:502)
org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1132)
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)
org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2527)
org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2516)
java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
java.lang.Thread.run(Unknown Source)

root cause
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'hello' defined in class path resource [springmvc-servlet.xml]: Instantiation of bean failed; nested exception is java.lang.NoClassDefFoundError:Could not initialize class com.smbms.controller.IndexController
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1155)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1099)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761)
org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867)
org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543)
org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:668)
org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:634)
org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:682)
org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:553)
org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:494)
org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:171)
javax.servlet.GenericServlet.init(GenericServlet.java:158)
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:504)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:502)
org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1132)
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)
org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2527)
org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2516)
java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
java.lang.Thread.run(Unknown Source)

root cause
java.lang.NoClassDefFoundError:Could not initialize class com.smbms.controller.IndexController
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
java.lang.reflect.Constructor.newInstance(Unknown Source)
org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:142)
org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:89)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1147)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1099)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761)
org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867)
org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543)
org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:668)
org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:634)
org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:682)
org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:553)
org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:494)
org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:171)
javax.servlet.GenericServlet.init(GenericServlet.java:158)
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:504)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:502)
org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1132)
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)
org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2527)
org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2516)
java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
java.lang.Thread.run(Unknown Source)

解决：

【1】首先是要搞清楚哪里引发了bug：最内层的bug是 NoClassDefFoundError--

Could not initialize class com.smbms.controller.IndexController

初始化我的 IndexController 失败。然后我查了一下 “NoClassDefFoundError 和 ClassNotFoundException 的区别”，得出以下结果：

（1）我们经常被java.lang.ClassNotFoundException和java.lang.NoClassDefFoundError这两个错误迷惑不清，尽管他们都与Java classpath有关，但是他们完全不同。

（2）NoClassDefFoundError发生在JVM在动态运行时，根据你提供的类名，在classpath中找到对应的类进
4000
行加载，但当它找不到这个类时，就发生了java.lang.NoClassDefFoundError的错误；

（3）ClassNotFoundException是在编译的时候在classpath中找不到对应的类而发生的错误。

（4）ClassNotFoundException比NoClassDefFoundError容易解决，是因为在编译时我们就知道错误发生，并且完全是由于环境的问题导致。而如果你在J2EE的环境下工作，并且得到NoClassDefFoundError的异常，而且对应的错误的类是确实存在的，这说明这个类对于类加载器来说，可能是不可见的。

【2】理顺异常的发送情况后，确定是controller的问题。
然后我在源代码中发现使用了log4j包，并且声明并使用了static变量。

static Logger log = Logger.getLogger(IndexController.class.getName());
log.debug("****************8hello,springmvc!");

【3】注释掉该段落后，bug消失。（还有两个问题，一是springmvc 的日志调试使用哪个包呢？二是去掉static后我把log变量移动到 handleRequestInternal() 方法内后依旧报错，后续解决！）

【4】参考博文：

1. http://blog.csdn.net/kikyo_wp/article/details/62216796 ；

2. http://blog.csdn.net/jamesjxin/article/details/46606307；