一个离奇的ArrayIndexOutOfBoundsException异常的排查过程

今天同事遇到了一个离奇的ArrayIndexOutOfBoundsException，找我协助定位，定位的过程很有意思，故而记录一下。

先按时序复盘一下

• 项目原先可正常运行。
• 没有修改任何依赖的情况下，从另一个项目移植了工具类BeanValidationUtil 后，报如下异常： org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:307) | Context initialization failed org.springframework.beans.factory.BeanDefinitionStoreException: Failed to read candidate component class: file [/Users/xxxxxxxxx/BeanValidationUtil.class]; nested exception is java.lang.ArrayIndexOutOfBoundsException: 48959 at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.findCandidateComponents(ClassPathScanningCandidateComponentProvider.java:260) 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:1419) at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1409) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:184) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:140) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:111) 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:131) at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:522) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:436) at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:384) at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:283) at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:111) at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:5135) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5658) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145) at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:1015) at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:991) at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:652) at org.apache.catalina.startup.HostConfig.manageApp(HostConfig.java:2015) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:301) at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819) at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801) at org.apache.catalina.mbeans.MBeanFactory.createContext(MBeanFactory.java:789) at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:573) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:301) at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819) at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801) at javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1468) at javax.management.remote.rmi.RMIConnectionImpl.access$300(RMIConnectionImpl.java:76) at javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1309) at javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1401) at javax.management.remote.rmi.RMIConnectionImpl.invoke(RMIConnectionImpl.java:829) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:324) at sun.rmi.transport.Transport$1.run(Transport.java:200) at sun.rmi.transport.Transport$1.run(Transport.java:197) at java.security.AccessController.doPrivileged(Native Method) at sun.rmi.transport.Transport.serviceCall(Transport.java:196) at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:568) at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:826) at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:683) at java.security.AccessController.doPrivileged(Native Method) at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:682) 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: java.lang.ArrayIndexOutOfBoundsException: 48959 at org.springframework.asm.ClassReader.readUnsignedShort(Unknown Source) at org.springframework.asm.ClassReader.accept(Unknown Source) at org.springframework.asm.ClassReader.accept(Unknown Source) at org.springframework.core.type.classreading.SimpleMetadataReader.<init>(SimpleMetadataReader.java:54) at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:80) at org.springframework.core.type.classreading.CachingMetadataReaderFactory.getMetadataReader(CachingMetadataReaderFactory.java:101) at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.findCandidateComponents(ClassPathScanningCandidateComponentProvider.java:236) ... 68 more

造成异常的工具类

/**
 * JSR349 Bean Validation工具类
 *
 * @author limu.zl
 */
public class BeanValidationUtil {
    /**
     * 验证失败时抛出ConstraintViolationException
     *
     * @param object 待验证对象
     * @param groups 验证group
     */
    public static void validateWithException(Object object, Class<?>... groups) {
        ValidatorFactory validatorFactory = Validation.buildDefaultValidatorFactory();

        // 国际化，强制用中文，ref：https://docs.oracle.com/javase/tutorial/i18n/locale/create.html
        Locale locale = new Locale.Builder().setLanguage("zh").setRegion("CN").build();

        // 国际化，指定语言，ref：https://www.ibm.com/developerworks/cn/java/j-cn-hibernate-validator/index.html
        MessageInterpolator interpolator = new LocalizedMessageInterpolator(validatorFactory.getMessageInterpolator(), locale);

        Validator classValidator = validatorFactory.usingContext()
                .messageInterpolator(interpolator)
                .getValidator();

        Set<ConstraintViolation<Object>> constraintViolations = classValidator.validate(object, groups);
        if (!constraintViolations.isEmpty()) {
            String messages = constraintViolations.stream()
                    .filter(t -> t instanceof ConstraintViolationImpl)
                    .map(t -> {
                        ConstraintViolationImpl t1 = (ConstraintViolationImpl) t;
                        return String.format("出问题的字段：%s，问题：%s", t1.getPropertyPath(), t1.getMessage());
                    })
                    .collect(Collectors.toList())
                    .toString();
            throw new IllegalArgumentException(messages);
        }
    }
}

分析

如代码所示，BeanValidationUtil 是个工具类，根本不在Spring容器上下文里，但异常栈却报到Spring的包里去了。

• 由于项目没有修改依赖，所以包冲突问题不太可能出现（这个项目原先也使用JSR349做Bean Validation），而且冲突的话异常应该是NoClassDefFoundError之类的异常。
• 尝试降低Hibernate Validation的版本到4.x，故障依旧。
• 百度、谷歌类似异常，无果。

经过20分钟的源码定位也没找到问题所在，于是我尝试逐步删除BeanValidationUtil的代码。发现当把lambda语法删光之后，项目就能正常启动了。

突然灵光一现，问同事 ： “这TM是不是个非常古老的项目啊？”

同事：“对啊，四五年了吧……”

于是分析了下pom.xml，发现用的是Spring 3 。隐约记得Spring 3不完全兼容JDK8，这个类中使用了Java 8的语法，所以导致了问题。

结果确认

既然猜测是Spring 3和Java 8不兼容导致，故而在搜索时，将关键词改为：spring 3 java 8 ArrayIndexOutOfBoundsException ，果然印证了自己的想法。

• ArrayOutOfBoundsException on Bean creation while using Java 8 constructs
• Spring BeanDefinitionStoreExcept-nested exception is java.lang.ArrayIndexOutOfBoundsException: 53804

反思

犯了经验主义错误，基于Spring 3的项目已经三四年没有见过了（Dubbo不算，哈哈哈。因为Dubbo当初的版本虽然依赖了Spring 3，但其实实际项目一般都会exclude掉，换上Spring 4），一直以为是个Spring 4的项目，没有从Spring版本与JDK的兼容性的方向上去考虑。

浪费了半小时。