异常java.lang.UnsupportedClassVersionError: Bad version number in .class file

昨天在中心建立了一个非常简单的struts1.x的工程，但是今天到家里怎么都打不开，一直报这样的错误：

严重: Begin event threw exception 

java.lang.reflect.InvocationTargetException 

    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 

    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) 

    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) 

    at java.lang.reflect.Method.invoke(Unknown Source) 

    at org.apache.commons.beanutils.PropertyUtilsBean.invokeMethod(PropertyUtilsBean.java:1773) 

    at org.apache.commons.beanutils.PropertyUtilsBean.setSimpleProperty(PropertyUtilsBean.java:1759) 

    at org.apache.commons.beanutils.PropertyUtilsBean.setNestedProperty(PropertyUtilsBean.java:1648) 

    at org.apache.commons.beanutils.PropertyUtilsBean.setProperty(PropertyUtilsBean.java:1677) 

    at org.apache.commons.beanutils.BeanUtilsBean.setProperty(BeanUtilsBean.java:1022) 

    at org.apache.commons.beanutils.BeanUtilsBean.populate(BeanUtilsBean.java:811) 

    at org.apache.commons.beanutils.BeanUtils.populate(BeanUtils.java:298) 

    at org.apache.commons.digester.SetPropertiesRule.begin(SetPropertiesRule.java:217) 

    at org.apache.commons.digester.Rule.begin(Rule.java:152) 

    at org.apache.commons.digester.Digester.startElement(Digester.java:1286) 

    at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.startElement(Unknown Source) 

    at com.sun.org.apache.xerces.internal.impl.dtd.XMLDTDValidator.startElement(Unknown Source) 

    at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.scanStartElement(Unknown Source) 

    at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown Source) 

    at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source) 

    at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source) 

    at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source) 

    at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(Unknown Source) 

    at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(Unknown Source) 

    at org.apache.commons.digester.Digester.parse(Digester.java:1572) 

    at org.apache.struts.action.ActionServlet.parseModuleConfigFile(ActionServlet.java:738) 

    at org.apache.struts.action.ActionServlet.initModuleConfig(ActionServlet.java:687) 

    at org.apache.struts.action.ActionServlet.init(ActionServlet.java:333) 

    at javax.servlet.GenericServlet.init(GenericServlet.java:212) 

    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1172) 

    at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:992) 

    at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4058) 

    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4371) 

    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:791) 

    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:771) 

    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:525) 

    at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:926) 

    at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:889) 

    at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:492) 

    at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1149) 

    at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:311) 

    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117) 

    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053) 

    at org.apache.catalina.core.StandardHost.start(StandardHost.java:719) 

    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045) 

    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443) 

    at org.apache.catalina.core.StandardService.start(StandardService.java:516) 

    at org.apache.catalina.core.StandardServer.start(StandardServer.java:710) 

    at org.apache.catalina.startup.Catalina.start(Catalina.java:578) 

    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 

    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) 

    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) 

    at java.lang.reflect.Method.invoke(Unknown Source) 

    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288) 

    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413) 

Caused by: java.lang.UnsupportedClassVersionError: Bad version number in .class file (unable to load class com.kay.web.form.UserForm) 

    at org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:1851) 

    at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:890) 

    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1354) 

    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1233) 

    at org.apache.struts.config.FormBeanConfig.formBeanClass(FormBeanConfig.java:358) 

    at org.apache.struts.config.FormBeanConfig.setType(FormBeanConfig.java:152) 

    ... 54 more 

2009-4-14 10:42:02 org.apache.struts.action.ActionServlet handleConfigException 

严重: Parsing error processing resource path /WEB-INF/struts-config.xml 

java.lang.reflect.InvocationTargetException 

    at org.apache.commons.digester.Digester.createSAXException(Digester.java:2792) 

    at org.apache.commons.digester.Digester.createSAXException(Digester.java:2818) 

    at org.apache.commons.digester.Digester.startElement(Digester.java:1289) 

    at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.startElement(Unknown Source) 

    at com.sun.org.apache.xerces.internal.impl.dtd.XMLDTDValidator.startElement(Unknown Source) 

    at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.scanStartElement(Unknown Source) 

    at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown Source) 

    at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source) 

    at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source) 

    at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source) 

    at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(Unknown Source) 

    at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(Unknown Source) 

    at org.apache.commons.digester.Digester.parse(Digester.java:1572) 

    at org.apache.struts.action.ActionServlet.parseModuleConfigFile(ActionServlet.java:738) 

    at org.apache.struts.action.ActionServlet.initModuleConfig(ActionServlet.java:687) 

    at org.apache.struts.action.ActionServlet.init(ActionServlet.java:333) 

    at javax.servlet.GenericServlet.init(GenericServlet.java:212) 

    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1172) 

    at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:992) 

    at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4058) 

    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4371) 

    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:791) 

    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:771) 

    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:525) 

    at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:926) 

    at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:889) 

    at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:492) 

    at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1149) 

    at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:311) 

    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117) 

    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053) 

    at org.apache.catalina.core.StandardHost.start(StandardHost.java:719) 

    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045) 

    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443) 

    at org.apache.catalina.core.StandardService.start(StandardService.java:516) 

    at org.apache.catalina.core.StandardServer.start(StandardServer.java:710) 

    at org.apache.catalina.startup.Catalina.start(Catalina.java:578) 

    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 

    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) 

    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) 

    at java.lang.reflect.Method.invoke(Unknown Source) 

    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288) 

    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413) 

2009-4-14 10:42:02 org.apache.catalina.core.ApplicationContext log 

信息: Marking servlet action as unavailable 

2009-4-14 10:42:02 org.apache.catalina.core.StandardContext loadOnStartup 

严重: Servlet /struts threw load() exception 

javax.servlet.UnavailableException: Parsing error processing resource path /WEB-INF/struts-config.xml 

    at org.apache.struts.action.ActionServlet.handleConfigException(ActionServlet.java:769) 

    at org.apache.struts.action.ActionServlet.parseModuleConfigFile(ActionServlet.java:745) 

    at org.apache.struts.action.ActionServlet.initModuleConfig(ActionServlet.java:687) 

    at org.apache.struts.action.ActionServlet.init(ActionServlet.java:333) 

    at javax.servlet.GenericServlet.init(GenericServlet.java:212) 

    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1172) 

    at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:992) 

    at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4058) 

    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4371) 

    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:791) 

    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:771) 

    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:525) 

    at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:926) 

    at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:889) 

    at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:492) 

    at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1149) 

    at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:311) 

    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117) 

    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053) 

    at org.apache.catalina.core.StandardHost.start(StandardHost.java:719) 

    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045) 

    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443) 

    at org.apache.catalina.core.StandardService.start(StandardService.java:516) 

    at org.apache.catalina.core.StandardServer.start(StandardServer.java:710) 

    at org.apache.catalina.startup.Catalina.start(Catalina.java:578) 

    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 

    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) 

    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) 

    at java.lang.reflect.Method.invoke(Unknown Source) 

    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288) 

    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:413)

后来发现是在中心创建这个工程的时候，使用的JDK是Java5但是家里是JDK6，所以或造成编译出错，解决方案如下（在Eclipse中）：

启动tomcat，OK！