记一次jdk升级引起的 Unsupported major.minor version 51.0

之前jdk 一直是1.6，tomcat 是6.x 版本，， 现在引入的新的jar， 出现

Caused by: java.lang.UnsupportedClassVersionError: org/apache/lucene/search/TopDocs : Unsupported major.minor version 51.0 (unable to load class org.apache.lucene.search.TopDocs)
at org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:2779)
at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:1126)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1614)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1493)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Class.java:2427)
at java.lang.Class.getDeclaredMethods(Class.java:1791)
at org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:460)
at org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:443)
at org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor.findPersistenceMetadata(PersistenceAnnotationBeanPostProcessor.java:363)
at org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor.postProcessMergedBeanDefinition(PersistenceAnnotationBeanPostProcessor.java:296)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyMergedBeanDefinitionPostProcessors(AbstractAutowireCapableBeanFactory.java:745)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:448)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory$1.run(AbstractAutowireCapableBeanFactory.java:409)
at java.security.AccessController.doPrivileged(Native Method)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:380)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:283)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:185)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:164)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:269)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:104)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1245)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1010)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:472)
... 30 more

难道是lucene 版本过高吗？ 51 表示的是jdk7， 于是乎升级jdk 吧！ 呼呼呼从1.6 升级到 1.7， 可是还有。。。

java.lang.reflect.InvocationTargetException
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.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
Caused by: java.lang.UnsupportedClassVersionError: net/jweb/listener/AppInitializerListener : Unsupported major.minor version 51.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:621)
at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.zeroturnaround.javarebel.yy.defineRebelClass(JRebel:180)
at com.zeroturnaround.javarebel.Cr.a(JRebel:660)
at com.zeroturnaround.javarebel.yA.a(JRebel:263)
at com.zeroturnaround.javarebel.ym.a(JRebel:182)
at com.zeroturnaround.javarebel.yA.loadReloadableClass(JRebel:324)
at com.zeroturnaround.javarebel.SDKIntegrationImpl.findReloadableClass(JRebel:85)
at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1614)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1493)
at org.apache.catalina.startup.WebAnnotationSet.loadClassAnnotation(WebAnnotationSet.java:145)
at org.apache.catalina.startup.WebAnnotationSet.loadApplicationListenerAnnotations(WebAnnotationSet.java:73)
at org.apache.catalina.startup.WebAnnotationSet.loadApplicationAnnotations(WebAnnotationSet.java:56)
at org.apache.catalina.startup.ContextConfig.applicationAnnotationsConfig(ContextConfig.java:297)
at org.apache.catalina.startup.ContextConfig.start(ContextConfig.java:1078)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:261)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:142)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4578)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:785)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
at org.apache.catalina.core.StandardService.start(StandardService.java:525)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:701)
at org.apache.catalina.startup.Catalina.start(Catalina.java:585)
... 6 more

检查一下errors 面板：
Description Resource Path Location Type
Java compiler level does not match the version of the installed Java project facet. lkStoreServer Unknown Faceted Project Problem (Java Version Mismatch)

哦！怎么会出现这个！ 机智的我网上一把搜，原来是这里：

重启，还是不行！

而且errors 面板还是各种错误：
Description Resource Path Location Type
Access restriction: The constructor BASE64Decoder() is not accessible due to restriction on required library E:\Java\jdk1.7.0\jre\lib\rt.jar DESUtil.java /lkStoreServer/src/java/net/jweb/common/util line 74 Java Problem
...

突然想到， java web 项目的依赖jdk 改成了1.7， 但是 编译的level 还是 1.6， 于是， 改！

重启， 还是一样的。。

...
Caused by: java.lang.UnsupportedClassVersionError: net/jweb/listener/AppInitializerListener : Unsupported major.minor version 51.0
...

郁闷， 我老油条了， 还会遇到这样的问题啊！ 网上搜索下 ， 在stackoverflow 看到，

This is because of a higher JDK during compile time and lower JDK during runtime. So you just need to update your JDK version, possible to JDK 7

http://stackoverflow.com/questions/10382929/how-to-fix-java-lang-unsupportedclassversionerror-unsupported-major-minor-versi

这个道理已经很明了了， 而且很容易理解 ， 我的运行时 jdk 版本低于编译时版本51， 也就是1.7， 想到自己本地安装了好几个版本的jdk ， 又想到tomcat 运行也是依赖jdk 的， 于是 检查一下， 果然这里有问题

把其中的 jdk 改成1.7 的， 重启tomcat ， 没那个错误了！！