Spring Data JPA forces CGLib proxying to non repos

Question

I am trying to migrate an existing Spring 3 JPA 2 Hibernate web application to Spring Data JPA. However just by adding the latest Spring Data JPA to the Maven project and configuring Spring Data as following

<jpa:repositories 
    base-package="myapp.persistence.spring" 
    entity-manager-factory-ref="entityManagerFactory"
    transaction-manager-ref="transactionManager" />

Spring starts complaining:

2012-07-31 16:54:23,153 ERROR [ContextLoader       ] - [Context initialization failed                                                                       ] - [remoteAddress=, remoteHost=, thread=pool-2-thread-1] org.springframework.web.context.ContextLoader
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'companyRepository' defined in file [C:\Development\ApplicationServer\apache-tomcat-7.0.27\webapps\myapp\WEB-INF\classes\myapp\persistence\CompanyRepository.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) ~[spring-beans-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456) ~[spring-beans-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294) ~[spring-beans-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225) ~[spring-beans-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291) ~[spring-beans-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193) ~[spring-beans-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:609) ~[spring-beans-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918) ~[spring-context-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:469) ~[spring-context-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:282) ~[spring-web-3.0.7.RELEASE.jar:3.0.7.RELEASE]
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:204) ~[spring-web-3.0.7.RELEASE.jar:3.0.7.RELEASE]
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:47) [spring-web-3.0.7.RELEASE.jar:3.0.7.RELEASE]
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4779) [catalina.jar:7.0.27]
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5273) [catalina.jar:7.0.27]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) [catalina.jar:7.0.27]
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1566) [catalina.jar:7.0.27]
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1556) [catalina.jar:7.0.27]
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303) [na:1.6.0_24]
    at java.util.concurrent.FutureTask.run(FutureTask.java:138) [na:1.6.0_24]
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) [na:1.6.0_24]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) [na:1.6.0_24]
    at java.lang.Thread.run(Thread.java:662) [na:1.6.0_24]
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) ~[spring-aop-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.aop.framework.ProxyCreatorSupport.createAopProxy(ProxyCreatorSupport.java:104) ~[spring-aop-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.aop.framework.ProxyFactory.getProxy(ProxyFactory.java:112) ~[spring-aop-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor.postProcessAfterInitialization(PersistenceExceptionTranslationPostProcessor.java:133) ~[spring-tx-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsAfterInitialization(AbstractAutowireCapableBeanFactory.java:407) ~[spring-beans-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1461) ~[spring-beans-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519) ~[spring-beans-3.1.2.RELEASE.jar:3.1.2.RELEASE]
    ... 21 common frames omitted

Notice that Spring Data is configured to scan package myapp.persistence.spring while the error above references a class from package myapp.persistence. When I add CGlib to the project everything including Spring Data works fine. But what's happening? I am a Spring rookie and quite puzzled. I could not figure out how Spring Data does it's proxy magic. At least the official examples do not include CGlib at all. Further information:

CompanyRepository is a simple self-made JPA-DAO using EntityManager:

@Repository
@Transactional(propagation = Propagation.MANDATORY)
public class CompanyRepository extends AbstractRepository<Company, Long> {
  …
}

Transactions are enabled via @Transactional and AspectJ compile time weaving. Context configuration snippet:

<tx:annotation-driven proxy-target-class="true" mode="aspectj"/>
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    <property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>

Deployed to Tomcat 7.0.27

Answer 1

As described in the reference documentation using <jpa:repositories /> activates persistence exception translation for Spring beans annotated with @Repository. As of the JavaDoc of @Repository the primary purpose of the annotation is exception translation which will be applied to the component annotated with it. If your class implements an interface plain JDK proxies can be used. If it does not - as in your case - CGLib is required to create the proxy. More details on that in the Spring reference documentation.

To use <jpa:repositories /> without CGLib you essentially have two choices in your scenario:

1. Introduce an interface for each component annotated with @Repository. This will still apply the persistence exception translation which is probably what you want.
2. Not use @Repository in the first place but rather @Component essentially disabling exception translation for these components.