引言： 在基于Spring开发中碰到了一个异常，并解决之。
1. 环境信息：
Spring 3.2.6, JDK 1.8,Mybatis 3.2.4
2. 运行简单的程序，出现以下错误信息：
DEBUG - Resolved location pattern [classpath*:com/freemarker/**/*.class] to resources [file [D:\GeneralStudies\.metadata\.plugins\org.eclipse.wst.server.core\tmp2\wtpwebapps\freemarkerTest\WEB-INF\classes\com\freemarker\controller\UserController.class], file [D:\GeneralStudies\.metadata\.plugins\org.eclipse.wst.server.core\tmp2\wtpwebapps\freemarkerTest\WEB-INF\classes\com\freemarker\domain\User.class], file [D:\GeneralStudies\.metadata\.plugins\org.eclipse.wst.server.core\tmp2\wtpwebapps\freemarkerTest\WEB-INF\classes\com\freemarker\mapper\UserMapper.class], file [D:\GeneralStudies\.metadata\.plugins\org.eclipse.wst.server.core\tmp2\wtpwebapps\freemarkerTest\WEB-INF\classes\com\freemarker\service\impl\UserServiceImpl.class], file [D:\GeneralStudies\.metadata\.plugins\org.eclipse.wst.server.core\tmp2\wtpwebapps\freemarkerTest\WEB-INF\classes\com\freemarker\service\UserService.class]] ERROR - Context initialization failed org.springframework.beans.factory.BeanDefinitionStoreException: Failed to read candidate component class: file [D:\GeneralStudies\.metadata\.plugins\org.eclipse.wst.server.core\tmp2\wtpwebapps\freemarkerTest\WEB-INF\classes\com\freemarker\controller\UserController.class]; nested exception is org.springframework.core.NestedIOException: ASM ClassReader failed to parse class file - probably due to a new Java class file version that isn't supported yet: file [D:\GeneralStudies\.metadata\.plugins\org.eclipse.wst.server.core\tmp2\wtpwebapps\freemarkerTest\WEB-INF\classes\com\freemarker\controller\UserController.class]; nested exception is java.lang.IllegalArgumentException at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.findCandidateComponents(ClassPathScanningCandidateComponentProvider.java:290) at org.springframework.context.annotation.ClassPathBeanDefinitionScanner.doScan(ClassPathBeanDefinitionScanner.java:242) at org.springframework.context.annotation.ComponentScanBeanDefinitionParser.parse(ComponentScanBeanDefinitionParser.java:84) at org.springframework.beans.factory.xml.NamespaceHandlerSupport.parse(NamespaceHandlerSupport.java:73) at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1438) at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1428) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:195) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:139) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:108) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:493) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:390) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:334) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:302) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:174) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:209) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:180) at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:125) at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:94) at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:130) at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:537) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:451) at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:651) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:599) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:665) at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:518) at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:459) at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136) at javax.servlet.GenericServlet.init(GenericServlet.java:158) at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1241) at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1154) at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1041) at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4932) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5218) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1396) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1386) at java.util.concurrent.FutureTask.run(FutureTask.java:266) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at java.lang.Thread.run(Thread.java:745) Caused by: org.springframework.core.NestedIOException: ASM ClassReader failed to parse class file - probably due to a new Java class file version that isn't supported yet: file [D:\GeneralStudies\.metadata\.plugins\org.eclipse.wst.server.core\tmp2\wtpwebapps\freemarkerTest\WEB-INF\classes\com\freemarker\controller\UserController.class]; nested exception is java.lang.IllegalArgumentException at org.springframework.core.type.classreading.SimpleMetadataReader.<init>(SimpleMetadataReader.java:56) at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:80) at org.springframework.core.type.classreading.CachingMetadataReaderFactory.getMetadataReader(CachingMetadataReaderFactory.java:102) at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.findCandidateComponents(ClassPathScanningCandidateComponentProvider.java:266) ... 39 more Caused by: java.lang.IllegalArgumentException at org.springframework.asm.ClassReader.<init>(Unknown Source) at org.springframework.asm.ClassReader.<init>(Unknown Source) at org.springframework.asm.ClassReader.<init>(Unknown Source) at org.springframework.core.type.classreading.SimpleMetadataReader.<init>(SimpleMetadataReader.java:53) ... 42 more 一月 05, 2018 12:41:53 下午 org.apache.catalina.core.ApplicationContext log 严重: StandardWrapper.Throwable org.springframework.beans.factory.BeanDefinitionStoreException: Failed to read candidate component class: file [D:\GeneralStudies\.metadata\.plugins\org.eclipse.wst.server.core\tmp2\wtpwebapps\freemarkerTest\WEB-INF\classes\com\freemarker\controller\UserController.class]; nested exception is org.springframework.core.NestedIOException: ASM ClassReader failed to parse class file - probably due to a new Java class file version that isn't supported yet: file [D:\GeneralStudies\.metadata\.plugins\org.eclipse.wst.server.core\tmp2\wtpwebapps\freemarkerTest\WEB-INF\classes\com\freemarker\controller\UserController.class]; nested exception is java.lang.IllegalArgumentException at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.findCandidateComponents(ClassPathScanningCandidateComponentProvider.java:290) at org.springframework.context.annotation.ClassPathBeanDefinitionScanner.doScan(ClassPathBeanDefinitionScanner.java:242) at org.springframework.context.annotation.ComponentScanBeanDefinitionParser.parse(ComponentScanBeanDefinitionParser.java:84) at org.springframework.beans.factory.xml.NamespaceHandlerSupport.parse(NamespaceHandlerSupport.java:73) at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1438) at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1428) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:195) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:139) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:108) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:493) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:390) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:334) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:302) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:174) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:209) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:180) at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:125) at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:94) at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:130) at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:537) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:451) at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:651) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:599) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:665) at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:518) at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:459) at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136) at javax.servlet.GenericServlet.init(GenericServlet.java:158) at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1241) at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1154) at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1041) at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4932) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5218) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1396) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1386) at java.util.concurrent.FutureTask.run(FutureTask.java:266) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at java.lang.Thread.run(Thread.java:745) Caused by: org.springframework.core.NestedIOException: ASM ClassReader failed to parse class file - probably due to a new Java class file version that isn't supported yet: file [D:\GeneralStudies\.metadata\.plugins\org.eclipse.wst.server.core\tmp2\wtpwebapps\freemarkerTest\WEB-INF\classes\com\freemarker\controller\UserController.class]; nested exception is java.lang.IllegalArgumentException at org.springframework.core.type.classreading.SimpleMetadataReader.<init>(SimpleMetadataReader.java:56) at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:80) at org.springframework.core.type.classreading.CachingMetadataReaderFactory.getMetadataReader(CachingMetadataReaderFactory.java:102) at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.findCandidateComponents(ClassPathScanningCandidateComponentProvider.java:266) ... 39 more Caused by: java.lang.IllegalArgumentException at org.springframework.asm.ClassReader.<init>(Unknown Source) at org.springframework.asm.ClassReader.<init>(Unknown Source) at org.springframework.asm.ClassReader.<init>(Unknown Source) at org.springframework.core.type.classreading.SimpleMetadataReader.<init>(SimpleMetadataReader.java:53) ... 42 more 一月 05, 2018 12:41:53 下午 org.apache.catalina.core.StandardContext loadOnStartup 严重: Servlet /freemarkerTest threw load() exception java.lang.IllegalArgumentException at org.springframework.asm.ClassReader.<init>(Unknown Source) at org.springframework.asm.ClassReader.<init>(Unknown Source) at org.springframework.asm.ClassReader.<init>(Unknown Source) at org.springframework.core.type.classreading.SimpleMetadataReader.<init>(SimpleMetadataReader.java:53) at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:80) at org.springframework.core.type.classreading.CachingMetadataReaderFactory.getMetadataReader(CachingMetadataReaderFactory.java:102) at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.findCandidateComponents(ClassPathScanningCandidateComponentProvider.java:266) at org.springframework.context.annotation.ClassPathBeanDefinitionScanner.doScan(ClassPathBeanDefinitionScanner.java:242) at org.springframework.context.annotation.ComponentScanBeanDefinitionParser.parse(ComponentScanBeanDefinitionParser.java:84) at org.springframework.beans.factory.xml.NamespaceHandlerSupport.parse(NamespaceHandlerSupport.java:73) at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1438) at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1428) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:195) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:139) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:108) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:493) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:390) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:334) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:302) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:174) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:209) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:180) at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:125) at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:94) at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:130) at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:537) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:451) at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:651) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:599) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:665) at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:518) at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:459) at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136) at javax.servlet.GenericServlet.init(GenericServlet.java:158) at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1241) at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1154) at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1041) at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4932) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5218) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1396) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1386) at java.util.concurrent.FutureTask.run(FutureTask.java:266) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at java.lang.Thread.run(Thread.java:745)
3. 问题分析
"ASM ClassReader failed to parse class file"是其中主要的原因。检查Maven的类库，没有发现问题，无asm显性依赖，其依赖产生于spring本身。故分析有可能是spring本身的问题造成了；但是这么流行的spring，怎么会出错了，我不能这么牛x碰到这么简单的问题吧？
难道是版本？除了版本之外，spring无大区别。经过一般搜索，网上还真有类似的问题：
Note that the Java 8 bytecode level (-target 1.8, as required by -source 1.8) is only fully supported as of Spring Framework 4.0. In particular, Spring 3.2 based applications need to be compiled with a maximum of Java 7 as the target, even if they happen to be deployed onto a Java 8 runtime. <span style="font-family:Arial, 'Helvetica Neue', Helvetica, sans-serif;color:#222222;font-size: 15px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: 19.5px; orphans: auto; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; display: inline !important; float: none; background-color: rgb(255, 249, 227);">Please upgrade to Spring 4 for Java 8 based applications.</span>
所以，看明白了吧，方案有两条：
a. 使用jdk7
b. 升级spring 4
4. 问题解决
最终选择了使用jdk7 ， 然后问题解决。