事件监听器 java.lang.NoClassDefFoundError

问题：配置事件监听器ContestStartedListener时出现错误。

问题代码如下：

java.lang.NoClassDefFoundError:org/springframework/aop/support/AopUtils

 

atorg.springframework.context.event.GenericApplicationListenerAdapter.supportsEventType(GenericApplicationListenerAdapter.java:59)

atorg.springframework.context.event.AbstractApplicationEventMulticaster.supportsEvent(AbstractApplicationEventMulticaster.java:241)

atorg.springframework.context.event.AbstractApplicationEventMulticaster.getApplicationListeners(AbstractApplicationEventMulticaster.java:170)

atorg.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:87)

atorg.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:333)

atorg.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:776)

atorg.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:485)

atorg.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)

atorg.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)

atlistener.testListeners.testResfreshed(testListeners.java:16)

atsun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

atsun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)

atsun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

atjava.lang.reflect.Method.invoke(Method.java:606)

atorg.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)

atorg.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)

atorg.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)

atorg.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)

atorg.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)

atorg.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)

atorg.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)

atorg.junit.runners.ParentRunner$3.run(ParentRunner.java:290)

atorg.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)

atorg.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)

atorg.junit.runners.ParentRunner.access$000(ParentRunner.java:58)

atorg.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)

atorg.junit.runners.ParentRunner.run(ParentRunner.java:363)

atorg.junit.runner.JUnitCore.run(JUnitCore.java:137)

atcom.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)

atcom.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:51)

atcom.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)

atcom.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

Caused by: java.lang.ClassNotFoundException:org.springframework.aop.support.AopUtils

atjava.net.URLClassLoader$1.run(URLClassLoader.java:366)

atjava.net.URLClassLoader$1.run(URLClassLoader.java:355)

atjava.security.AccessController.doPrivileged(Native Method)

atjava.net.URLClassLoader.findClass(URLClassLoader.java:354)

atjava.lang.ClassLoader.loadClass(ClassLoader.java:425)

atsun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)

atjava.lang.ClassLoader.loadClass(ClassLoader.java:358)

... 32 more

原因及解决过程：

1.由于listener不需要获取bean，因此在xml文件中没有放置id属性。百度有人说是xml文件配置出错，首先添加xml文件中的bean id属性，运行仍然报错。

2.报错aop工具包找不到类的异常，将aop核心包spring-aop-4.0.4RELEASE包导入，成功运行。

引伸：

1.这个不是复杂的java.lang.NoClassDefFoundError错误，NoClassDefFoundError错误涉及到JVM在编译运行时，根据类名在classpath中无法找到类。检查方面如下：

1）对应jar包是否存在 和定义  2）相应类库是否可用  3）相关静态初始化是否成功   4）是否使用多个类加载器

2.ClassNotFoundException异常是编译时异常，根据类名在classpath中找不到类。