1. The purpose of this post

I would demo how to use java to solve this exception when @Autowire a property in spring.

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'myService': Injection of autowired dependencies failed; nested exception is org.springframework.aop.framework.AopConfigException: Could not generate CGLIB subclass of class [class java8.learn.autowire.MyObject]: Common causes of this problem include using a final class or a non-visible class; nested exception is java.lang.IllegalArgumentException: Cannot subclass final class java8.learn.autowire.MyObject
        at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:372) ~[spring-beans-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1268) ~[spring-beans-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553) ~[spring-beans-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:312) ~[spring-beans-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:308) ~[spring-beans-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761) ~[spring-beans-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867) ~[spring-context-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543) ~[spring-context-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693) [spring-boot-1.5.12.RELEASE.jar:1.5.12.RELEASE]
        at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360) [spring-boot-1.5.12.RELEASE.jar:1.5.12.RELEASE]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) [spring-boot-1.5.12.RELEASE.jar:1.5.12.RELEASE]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.12.RELEASE.jar:1.5.12.RELEASE]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.12.RELEASE.jar:1.5.12.RELEASE]
        at java8.learn.TestJava8App.main(TestJava8App.java:18) [classes/:na]
Caused by: org.springframework.aop.framework.AopConfigException: Could not generate CGLIB subclass of class [class java8.learn.autowire.MyObject]: Common causes of this problem include using a final class or a non-visible class; nested exception is java.lang.IllegalArgumentException: Cannot subclass final class java8.learn.autowire.MyObject
        at org.springframework.aop.framework.CglibAopProxy.getProxy(CglibAopProxy.java:211) ~[spring-aop-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.aop.framework.ProxyFactory.getProxy(ProxyFactory.java:109) ~[spring-aop-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.context.annotation.ContextAnnotationAutowireCandidateResolver.buildLazyResolutionProxy(ContextAnnotationAutowireCandidateResolver.java:115) ~[spring-context-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.context.annotation.ContextAnnotationAutowireCandidateResolver.getLazyResolutionProxyIfNecessary(ContextAnnotationAutowireCandidateResolver.java:50) ~[spring-context-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1063) ~[spring-beans-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585) ~[spring-beans-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) ~[spring-beans-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366) ~[spring-beans-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        ... 16 common frames omitted
Caused by: java.lang.IllegalArgumentException: Cannot subclass final class java8.learn.autowire.MyObject
        at org.springframework.cglib.proxy.Enhancer.generateClass(Enhancer.java:565) ~[spring-core-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.cglib.transform.TransformingClassGenerator.generateClass(TransformingClassGenerator.java:33) ~[spring-core-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.cglib.core.DefaultGeneratorStrategy.generate(DefaultGeneratorStrategy.java:25) ~[spring-core-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.aop.framework.CglibAopProxy$ClassLoaderAwareUndeclaredThrowableStrategy.generate(CglibAopProxy.java:999) ~[spring-aop-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.cglib.core.AbstractClassGenerator.generate(AbstractClassGenerator.java:329) ~[spring-core-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.cglib.proxy.Enhancer.generate(Enhancer.java:492) ~[spring-core-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:93) ~[spring-core-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:91) ~[spring-core-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.cglib.core.internal.LoadingCache$2.call(LoadingCache.java:54) ~[spring-core-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[na:1.8.0_121]
        at org.springframework.cglib.core.internal.LoadingCache.createEntry(LoadingCache.java:61) ~[spring-core-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.cglib.core.internal.LoadingCache.get(LoadingCache.java:34) ~[spring-core-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData.get(AbstractClassGenerator.java:116) ~[spring-core-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:291) ~[spring-core-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.cglib.proxy.Enhancer.createHelper(Enhancer.java:480) ~[spring-core-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.cglib.proxy.Enhancer.createClass(Enhancer.java:337) ~[spring-core-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.aop.framework.ObjenesisCglibAopProxy.createProxyClassAndInstance(ObjenesisCglibAopProxy.java:55) ~[spring-aop-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        at org.springframework.aop.framework.CglibAopProxy.getProxy(CglibAopProxy.java:201) ~[spring-aop-4.3.16.RELEASE.jar:4.3.16.RELEASE]
        ... 23 common frames omitted

2. Environments

  • java 1.8+
  • spring framework 4+

3. The Code

The object to be autowired:

@Component
public final class MyObject {
    public String getTime() {
        return (new Date()).toString();
    }
}

The class is final because I don’t want others to override its methods. But when I use @Autowire and @Lazy in other classes like this:

@Autowired @Lazy
private MyObject myObject;

Run the app, I got the above exceptions.

Because spring would use CGLIB to generate a subclass of the @Lazy class, and MyObject is final,so the exception occurred, I change the code like this:

@Component
public class MyObject { //remove final
    public String getTime() {
        return (new Date()).toString();
    }
}

Clean and re-run the app, everything works fine now.