深入Spring Boot: 怎樣排查 java.lang.ArrayStoreException
這個demo來說明怎樣排查一個spring boot 1應用升級到spring boot 2時可能出現的java.lang.ArrayStoreException
。
demo地址:https://github.com/hengyunabc/spring-boot-inside/tree/master/demo-ArrayStoreException
demo裏有兩個模塊,springboot1-starter
和springboot2-demo
。
在springboot1-starter
模塊裏,是一個簡單的HealthIndicator
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
則是一個簡單的spring boot2應用,引用了springboot1-starter
模塊。
把工程導入IDE,執行springboot2-demo
裏的ArrayStoreExceptionDemoApplication
,拋出的異常是
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
下面來排查這個問題。
在IDE裏,新建一個斷點,類型是Java Exception Breakpoint
(如果不清楚怎麽添加,可以搜索對應IDE的使用文檔),異常類是上面拋出來的java.lang.ArrayStoreException
。
當斷點起效時,查看AnnotationUtils.findAnnotation(Class<?>, Class<A>, Set<Annotation>) line: 686
函數的參數。
可以發現
- clazz是
class com.example.springboot1starter.MyHealthIndicatorAutoConfiguration$$EnhancerBySpringCGLIB$$945c1f
- annotationType是
interface org.springframework.boot.actuate.endpoint.annotation.Endpoint
說明是嘗試從MyHealthIndicatorAutoConfiguration
裏查找@Endpoint
信息時出錯的。
MyHealthIndicatorAutoConfiguration
上的確沒有@Endpoint
,但是為什麽拋出java.lang.ArrayStoreException
?
嘗試以簡單例子復現異常
首先嘗試直接 new MyHealthIndicatorAutoConfiguration :
public static void main(String[] args) { MyHealthIndicatorAutoConfiguration cc = new MyHealthIndicatorAutoConfiguration(); }
本以為會拋出異常來,但是發現執行正常。
再仔細看異常棧,可以發現是在at java.lang.Class.getDeclaredAnnotation(Class.java:3458)
拋出的異常,則再嘗試下面的代碼:
public static void main(String[] args) { MyHealthIndicatorAutoConfiguration.class.getDeclaredAnnotation(Endpoint.class); }
發現可以復現異常了:
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)
為什麽會是java.lang.ArrayStoreException
再仔細看異常信息:java.lang.ArrayStoreException: sun.reflect.annotation.TypeNotPresentExceptionProxy
ArrayStoreException
是一個數組越界的異常,它只有一個String信息,並沒有cause
。
那麽我們嘗試在 sun.reflect.annotation.TypeNotPresentExceptionProxy
的構造函數裏打斷點。
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; }
在斷點裏,我們可以發現:
- typeName是
org.springframework.boot.actuate.autoconfigure.EndpointAutoConfiguration
- cause是
java.lang.ClassNotFoundException: org.springframework.boot.actuate.autoconfigure.EndpointAutoConfiguration
終於真相大白了,是找不到org.springframework.boot.actuate.autoconfigure.EndpointAutoConfiguration
這個類。
那麽它是怎麽變成ArrayStoreException
的呢?
仔細看下代碼,可以發現AnnotationParser.parseClassValue
把異常包裝成為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()); } }
然後在sun.reflect.annotation.AnnotationParser.parseClassArray(int, ByteBuffer, ConstantPool, Class<?>)
裏嘗試直接設置到數組裏
// sun.reflect.annotation.AnnotationParser.parseClassArray(int, ByteBuffer, ConstantPool, Class<?>) result[i] = parseClassValue(buf, constPool, container);
而這裏數組越界了,ArrayStoreException
只有越界的Object
的類型信息,也就是上面的
java.lang.ArrayStoreException: sun.reflect.annotation.TypeNotPresentExceptionProxy
解決問題
發現是java.lang.ClassNotFoundException: org.springframework.boot.actuate.autoconfigure.EndpointAutoConfiguration
,則加上@ConditionalOnClass
的檢查就可以了:
@Configuration @AutoConfigureBefore(EndpointAutoConfiguration.class) @AutoConfigureAfter(HealthIndicatorAutoConfiguration.class) @ConditionalOnClass(value = {HealthIndicator.class, EndpointAutoConfiguration.class}) public class MyHealthIndicatorAutoConfiguration {
準確來說是spring boot2把一些類的package改了:
spring boot 1裏類名是:
- org.springframework.boot.actuate.autoconfigure.EndpointAutoConfiguration
spring boot 2裏類名是:
- org.springframework.boot.actuate.autoconfigure.endpoint.EndpointAutoConfiguration
總結
- 當類加載時,並不會加載它的annotation的field所引用的
Class<?>
,當調用Class.getDeclaredAnnotation(Class<A>)
裏才會加載以上面的例子來說,就是
@AutoConfigureBefore(EndpointAutoConfiguration.class)
裏的EndpointAutoConfiguration
並不會和MyHealthIndicatorAutoConfiguration
一起被加載。 - jdk內部的解析字節碼的代碼不合理,把
ClassNotFoundException
異常吃掉了 - 排查問題需要一步步深入調試
深入Spring Boot: 怎樣排查 java.lang.ArrayStoreException