java.lang.UnsupportedClassVersionError: org/eclipse/jetty/util/annotation/ManagedObject : Unsupporte

今天 在 eclipse 运行 junit 单元测试，报错如下：

java.lang.UnsupportedClassVersionError: org/eclipse/jetty/util/annotation/ManagedObject : Unsupported major.minor version 51.0
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
	at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
	at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
	at java.net.URLClassLoader.access$000(URLClassLoader.java:56)
	at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:276)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
	at org.springframework.core.type.classreading.RecursiveAnnotationAttributesVisitor.visitEnd(AnnotationAttributesReadingVisitor.java:181)
	at org.springframework.asm.ClassReader.readAnnotationValues(ClassReader.java:1788)
	at org.springframework.asm.ClassReader.accept(ClassReader.java:642)
	at org.springframework.asm.ClassReader.accept(ClassReader.java:508)
	at org.springframework.core.type.classreading.SimpleMetadataReader.<init>(SimpleMetadataReader.java:64)
	at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:82)
	at org.springframework.core.type.classreading.CachingMetadataReaderFactory.getMetadataReader(CachingMetadataReaderFactory.java:102)
	at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:77)
	at org.springframework.context.annotation.ConfigurationClassUtils.checkConfigurationClassCandidate(ConfigurationClassUtils.java:85)
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:278)
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:239)
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:254)
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:94)
	at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:606)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:462)
	at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
	at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)
	at com.baidu.rigel.dmap.dao.TaskDaoTest.before(TaskDaoTest.java:32)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:24)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
	at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

后来经过搜索 发现 这篇 blog： http://www.111cn.net/jsp/Jsp-Servlet/45158.htm

大意就是  

Unsupported major.minor version 51.0  表示 jdk版本不一致

<span style="color: rgb(51, 51, 51); font-family: Simsun; font-size: 15px; line-height: 28px;">用jdk7编译的class文件放到基于jdk6运行在tomcat之中，就会报这个错。</span>

<span style="color: rgb(51, 51, 51); font-family: Simsun; font-size: 15px; line-height: 28px;"><span style="color: rgb(51, 51, 51); font-family: Simsun; font-size: 14px; line-height: 28px;">总结：</span><span style="font-family: Simsun; font-size: 14px; line-height: 28px; color: rgb(255, 0, 0);">不同的JDK版本使用的major.minor不同，所以会导致这个错误。在项目中要使用当前电脑配置的JDK版本，切忌张冠李戴。</span><br style="color: rgb(51, 51, 51); font-family: Simsun; font-size: 14px; line-height: 28px;" /><span style="color: rgb(51, 51, 51); font-family: Simsun; font-size: 14px; line-height: 28px;">知识扩充：major.minor version，它相当于一个软件的主次版本号，只是在这里是标识的一个Java Class的主版本号和次版本号。</span>
</span>

解决办法： 就这个报错而言，我们的项目使用jdk6，但 maven 配置中 jetty的这个版本 为 9.2.2.v20140723。搜索发现，jetty该版本的最低要求为 jdk7.

故 不匹配 导致的。

解决办法就是  将maven中 依赖的 jetty的版本改一下，改成   8.1.16.v20140903 版本。

如下所示：

<dependency>
<groupId>org.eclipse.jetty.aggregate</groupId>
<artifactId>jetty-all</artifactId>
<version>8.1.16.v20140903</version>
</dependency>