Spring: Is CGLIB required for injection of a concrete class using @Resource

Question

I have configured Spring 3.0.6 with AspectJ LTW using spring-instrument.jar and:

<context:load-time-weaver aspectj-weaving="on" weaver-class="org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver" />

When removing CGLIB from dependencies, I'm getting the following exception even after MyBean is created (and its @PostConstruct is run):

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'crawlItemService' defined in file [/path/to/project/foo/bar/MyBean.class]: Initialization of bean failed; nested exception is org.springframework.aop.framework.AopConfigException: Cannot proxy target class because CGLIB2 is not available. Add CGLIB to the class path or specify proxy interfaces.
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:527)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:291)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
    at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.autowireResource(CommonAnnotationBeanPostProcessor.java:435)
    at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.getResource(CommonAnnotationBeanPostProcessor.java:409)
    at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor$ResourceElement.getResourceToInject(CommonAnnotationBeanPostProcessor.java:541)
    at org.springframework.beans.factory.annotation.InjectionMetadata$InjectedElement.inject(InjectionMetadata.java:147)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:84)
    at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessPropertyValues(CommonAnnotationBeanPostProcessor.java:297)
    ... 72 more
Caused by: org.springframework.aop.framework.AopConfigException: Cannot proxy target class because CGLIB2 is not available. Add CGLIB to the class path or specify proxy interfaces.
    at org.springframework.aop.framework.DefaultAopProxyFactory.createAopProxy(DefaultAopProxyFactory.java:67)
    at org.springframework.aop.framework.ProxyCreatorSupport.createAopProxy(ProxyCreatorSupport.java:104)
    at org.springframework.aop.framework.ProxyFactory.getProxy(ProxyFactory.java:112)
    at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.createProxy(AbstractAutoProxyCreator.java:476)
    at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.wrapIfNecessary(AbstractAutoProxyCreator.java:362)
    at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.postProcessAfterInitialization(AbstractAutoProxyCreator.java:322)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsAfterInitialization(AbstractAutowireCapableBeanFactory.java:407)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1426)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
    ... 83 more

Does it mean that I should have CGLIB even in existence of a load time weaver?

Solution 1

After over 3 hours of investigations of the code and changing Spring bean definition XMLs, I finally found the problem. This could be found from this part of stacktrace, which I noticed after finding the solution:

at org.springframework.scheduling.annotation.AsyncAnnotationBeanPostProcessor.postProcessAfterInitialization(AsyncAnnotationBeanPostProcessor.java:126)

Based on the note here, I changed all proxy-target-class attributes to false in <aop:config>, <aop:aspectj-autoproxy>, and <tx:annotation-driven>, but to no success.

Then I started removing parts of my XML definition to find which one fixes this problem. Commenting <task:annotation-driven> helped and the problem resolved. I then saw that this element has a mode attribute which I didn't specified, so its default value, proxy, is used, and so CGLIB is required. As I changed mode="aspectj" the problem resolved:

<task:annotation-driven scheduler="dataProviderScheduler" executor="dataProviderExecutor" mode="aspectj" />

Solution 2

No, but it is required to create AOP proxies (Cannot proxy target class). Does your class have one of:

• @Transactional
• @Cacheable
• @Async
• ...

annotations? Or maybe there is some external aspect around methods of this class? Nevertheless, AspectJ compiler should take care of weaving, AFAIR CGLIB should not be used. Can you show us your code?

In my case to correctly enable load time weaving for transaction support I had to add:

 <context:load-time-weaver/>
 <tx:annotation-driven mode="aspectj"/>
 <aop:config proxy-target-class="true"/>

Have a look at a working example.

Solution 3

If you are using Spring APO you need to include CGLIB. There are two ways to add this to your project

1. Download CGLIB library file and add it to your library files. http://www.java2s.com/Code/Jar/c/Downloadcglib22jar.htm

2. Add the Maven dependency in your pom.xml file

   https://mvnrepository.com/artifact/cglib/cglib/2.2.2

---

<dependency>
    <groupId>cglib</groupId>
    <artifactId>cglib</artifactId>
    <version>2.2</version>
</dependency>