这个demo来说明怎样排查一个spring boot 1应用升级到spring boot 2时可能出现的java.lang.ArrayStoreException
。
demo地址:https://github.com/hengyunabc/spring-boot-inside/tree/master/demo-ArrayStoreException
demo里有两个模块,springboot1-starter
和springboot2-demo
。
在springboot1-starter
模块里,是一个简单的HealthIndicator
实现
public class MyHealthIndicator extends AbstractHealthIndicator { @Override protected void doHealthCheck(Builder builder) throws Exception { builder.status(Status.UP); builder.withDetail("hello", "world"); } }
@Configuration @AutoConfigureBefore(EndpointAutoConfiguration.class) @AutoConfigureAfter(HealthIndicatorAutoConfiguration.class) @ConditionalOnClass(value = { HealthIndicator.class }) public class MyHealthIndicatorAutoConfiguration { @Bean @ConditionalOnMissingBean(MyHealthIndicator.class) @ConditionalOnEnabledHealthIndicator("my") public MyHealthIndicator myHealthIndicator() { return new MyHealthIndicator(); } }
springboot2-demo
则是一个简单的spring boot2应用,引用了springboot1-starter
模块。
把工程导入IDE,执行springboot2-demo
里的ArrayStoreExceptionDemoApplication
,抛出的异常是
Caused by: java.lang.ArrayStoreException: sun.reflect.annotation.TypeNotPresentExceptionProxy at sun.reflect.annotation.AnnotationParser.parseClassArray(AnnotationParser.java:724) ~[na:1.8.0_112] at sun.reflect.annotation.AnnotationParser.parseArray(AnnotationParser.java:531) ~[na:1.8.0_112] at sun.reflect.annotation.AnnotationParser.parseMemberValue(AnnotationParser.java:355) ~[na:1.8.0_112] at sun.reflect.annotation.AnnotationParser.parseAnnotation2(AnnotationParser.java:286) ~[na:1.8.0_112] at sun.reflect.annotation.AnnotationParser.parseAnnotations2(AnnotationParser.java:120) ~[na:1.8.0_112] at sun.reflect.annotation.AnnotationParser.parseAnnotations(AnnotationParser.java:72) ~[na:1.8.0_112] at java.lang.Class.createAnnotationData(Class.java:3521) ~[na:1.8.0_112] at java.lang.Class.annotationData(Class.java:3510) ~[na:1.8.0_112] at java.lang.Class.createAnnotationData(Class.java:3526) ~[na:1.8.0_112] at java.lang.Class.annotationData(Class.java:3510) ~[na:1.8.0_112] at java.lang.Class.getAnnotation(Class.java:3415) ~[na:1.8.0_112] at java.lang.reflect.AnnotatedElement.isAnnotationPresent(AnnotatedElement.java:258) ~[na:1.8.0_112] at java.lang.Class.isAnnotationPresent(Class.java:3425) ~[na:1.8.0_112] at org.springframework.core.annotation.AnnotatedElementUtils.hasAnnotation(AnnotatedElementUtils.java:575) ~[spring-core-5.0.4.RELEASE.jar:5.0.4.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.isHandler(RequestMappingHandlerMapping.java:177) ~[spring-webmvc-5.0.4.RELEASE.jar:5.0.4.RELEASE] at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.initHandlerMethods(AbstractHandlerMethodMapping.java:217) ~[spring-webmvc-5.0.4.RELEASE.jar:5.0.4.RELEASE] at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.afterPropertiesSet(AbstractHandlerMethodMapping.java:188) ~[spring-webmvc-5.0.4.RELEASE.jar:5.0.4.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.afterPropertiesSet(RequestMappingHandlerMapping.java:129) ~[spring-webmvc-5.0.4.RELEASE.jar:5.0.4.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1769) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1706) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE] ... 16 common frames omitted
使用 Java Exception Breakpoint
下面来排查这个问题。
在IDE里,新建一个断点,类型是Java Exception Breakpoint
(如果不清楚怎么添加,可以搜索对应IDE的使用文档),异常类是上面抛出来的java.lang.ArrayStoreException
。
当断点起效时,查看AnnotationUtils.findAnnotation(Class<?>, Class<A>, Set<Annotation>) line: 686
函数的参数。
可以发现
- clazz是
class com.example.springboot1starter.MyHealthIndicatorAutoConfiguration$$EnhancerBySpringCGLIB$$945c1f
- annotationType是
interface org.springframework.boot.actuate.endpoint.annotation.Endpoint
说明是尝试从MyHealthIndicatorAutoConfiguration
里查找@Endpoint
信息时出错的。
MyHealthIndicatorAutoConfiguration
上的确没有@Endpoint
,但是为什么抛出java.lang.ArrayStoreException
?
尝试以简单例子复现异常
首先尝试直接 new MyHealthIndicatorAutoConfiguration :
public static void main(String[] args) { MyHealthIndicatorAutoConfiguration cc = new MyHealthIndicatorAutoConfiguration(); }
本以为会抛出异常来,但是发现执行正常。
再仔细看异常栈,可以发现是在at java.lang.Class.getDeclaredAnnotation(Class.java:3458)
抛出的异常,则再尝试下面的代码:
public static void main(String[] args) { MyHealthIndicatorAutoConfiguration.class.getDeclaredAnnotation(Endpoint.class); }
发现可以复现异常了:
Exception in thread "main" java.lang.ArrayStoreException: sun.reflect.annotation.TypeNotPresentExceptionProxy at sun.reflect.annotation.AnnotationParser.parseClassArray(AnnotationParser.java:724) at sun.reflect.annotation.AnnotationParser.parseArray(AnnotationParser.java:531) at sun.reflect.annotation.AnnotationParser.parseMemberValue(AnnotationParser.java:355) at sun.reflect.annotation.AnnotationParser.parseAnnotation2(AnnotationParser.java:286) at sun.reflect.annotation.AnnotationParser.parseAnnotations2(AnnotationParser.java:120) at sun.reflect.annotation.AnnotationParser.parseAnnotations(AnnotationParser.java:72) at java.lang.Class.createAnnotationData(Class.java:3521) at java.lang.Class.annotationData(Class.java:3510) at java.lang.Class.getDeclaredAnnotation(Class.java:3458)
为什么会是java.lang.ArrayStoreException
再仔细看异常信息:java.lang.ArrayStoreException: sun.reflect.annotation.TypeNotPresentExceptionProxy
ArrayStoreException
是一个数组越界的异常,它只有一个String信息,并没有cause
。
那么我们尝试在 sun.reflect.annotation.TypeNotPresentExceptionProxy
的构造函数里打断点。
public class TypeNotPresentExceptionProxy extends ExceptionProxy { private static final long serialVersionUID = 5565925172427947573L; String typeName; Throwable cause; public TypeNotPresentExceptionProxy(String typeName, Throwable cause) { this.typeName = typeName; this.cause = cause; }
在断点里,我们可以发现:
- typeName是
org.springframework.boot.actuate.autoconfigure.EndpointAutoConfiguration
- cause是
java.lang.ClassNotFoundException: org.springframework.boot.actuate.autoconfigure.EndpointAutoConfiguration
终于真相大白了,是找不到org.springframework.boot.actuate.autoconfigure.EndpointAutoConfiguration
这个类。
那么它是怎么变成ArrayStoreException
的呢?
仔细看下代码,可以发现AnnotationParser.parseClassValue
把异常包装成为Object
//sun.reflect.annotation.AnnotationParser.parseClassValue(ByteBuffer, ConstantPool, Class<?>) private static Object parseClassValue(ByteBuffer buf, ConstantPool constPool, Class<?> container) { int classIndex = buf.getShort() & 0xFFFF; try { try { String sig = constPool.getUTF8At(classIndex); return parseSig(sig, container); } catch (IllegalArgumentException ex) { // support obsolete early jsr175 format class files return constPool.getClassAt(classIndex); } } catch (NoClassDefFoundError e) { return new TypeNotPresentExceptionProxy("[unknown]", e); } catch (TypeNotPresentException e) { return new TypeNotPresentExceptionProxy(e.typeName(), e.getCause()); } }
然后在sun.reflect.annotation.AnnotationParser.parseClassArray(int, ByteBuffer, ConstantPool, Class<?>)
里尝试直接设置到数组里
// sun.reflect.annotation.AnnotationParser.parseClassArray(int, ByteBuffer, ConstantPool, Class<?>) result[i] = parseClassValue(buf, constPool, container);
而这里数组越界了,ArrayStoreException
只有越界的Object
的类型信息,也就是上面的
java.lang.ArrayStoreException: sun.reflect.annotation.TypeNotPresentExceptionProxy
解决问题
发现是java.lang.ClassNotFoundException: org.springframework.boot.actuate.autoconfigure.EndpointAutoConfiguration
,则加上@ConditionalOnClass
的检查就可以了:
@Configuration @AutoConfigureBefore(EndpointAutoConfiguration.class) @AutoConfigureAfter(HealthIndicatorAutoConfiguration.class) @ConditionalOnClass(value = {HealthIndicator.class, EndpointAutoConfiguration.class}) public class MyHealthIndicatorAutoConfiguration {
准确来说是spring boot2把一些类的package改了:
spring boot 1里类名是:
- org.springframework.boot.actuate.autoconfigure.EndpointAutoConfiguration
spring boot 2里类名是:
- org.springframework.boot.actuate.autoconfigure.endpoint.EndpointAutoConfiguration
总结
- 当类加载时,并不会加载它的annotation的field所引用的
Class<?>
,当调用Class.getDeclaredAnnotation(Class<A>)
里才会加载以上面的例子来说,就是
@AutoConfigureBefore(EndpointAutoConfiguration.class)
里的EndpointAutoConfiguration
并不会和MyHealthIndicatorAutoConfiguration
一起被加载。 - jdk内部的解析字节码的代码不合理,把
ClassNotFoundException
异常吃掉了 - 排查问题需要一步步深入调试