AOP problem running Spring unit tests

Question

I have a Spring web application which is configured to use JDK proxying for AOP. The AOP annotations (such as @Transactional) are declared on the interfaces, rather than the implementation classes.

The application itself works fine, but when I run the unit tests, it seems to be attempting to use CGLIB for the AOP functionality (instead of JDK proxying). This causes the tests to fail - I've appended the stack trace below.

I don't understand why CGLIB is being used when I run the tests, because the Spring configuration is largely the same as when the application is running. One possibly significant difference is that the test configuration uses a DataSourceTransactionManager instead of a JTA transaction manager. The test classes themselves all extend AbstractJUnit4SpringContextTests, could it be that this class is somehow hard-wired to use CGLIB?

Caused by: org.springframework.aop.framework.AopConfigException: Could not generate CGLIB subclass of class [class $Proxy25]: 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 class $Proxy25
    at org.springframework.aop.framework.Cglib2AopProxy.getProxy(Cglib2AopProxy.java:213)
    at org.springframework.aop.framework.ProxyFactory.getProxy(ProxyFactory.java:110)
    at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.createProxy(AbstractAutoProxyCreator.java:488)
    at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.wrapIfNecessary(AbstractAutoProxyCreator.java:363)
    at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.postProcessAfterInitialization(AbstractAutoProxyCreator.java:324)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsAfterInitialization(AbstractAutowireCapableBeanFactory.java:361)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1343)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:473)
    ... 79 more
Caused by: java.lang.IllegalArgumentException: Cannot subclass final class class $Proxy25
    at net.sf.cglib.proxy.Enhancer.generateClass(Enhancer.java:446)
    at net.sf.cglib.transform.TransformingClassGenerator.generateClass(TransformingClassGenerator.java:33)
    at net.sf.cglib.core.DefaultGeneratorStrategy.generate(DefaultGeneratorStrategy.java:25)
    at net.sf.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:216)
    at net.sf.cglib.proxy.Enhancer.createHelper(Enhancer.java:377)
    at net.sf.cglib.proxy.Enhancer.create(Enhancer.java:285)
    at org.springframework.aop.framework.Cglib2AopProxy.getProxy(Cglib2AopProxy.java:201)
    ... 86 more

EDIT: One of the commentators requested that I post the Spring configuration. I've included it below in abbreviated form (i.e. irrelevant beans and XML namespaces omitted).

spring-servlet.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans>        
    <!-- ANNOTATION SUPPORT -->
    <!-- Include basic annotation support -->
    <context:annotation-config/>  

    <!-- CONTROLLERS -->
    <!-- Controllers, force scanning -->
    <context:component-scan base-package="com.onebigplanet.web.controller,com.onebigplanet.web.ws.*"/> 

    <!-- Post-processor for @Aspect annotated beans, which converts them into AOP advice -->
    <bean class="org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator">
        <property name="proxyTargetClass" value="true"/>
    </bean>

    <!-- An @Aspect bean that converts exceptions thrown in POJO service implementation classes to runtime exceptions  -->
    <bean id="permissionAdvisor" class="com.onebigplanet.web.advisor.PermissionAdvisor"/>
    <bean id="businessIntelligenceAdvisor" class="com.onebigplanet.web.advisor.bi.BusinessIntelligenceAdvisor"/>  

    <!-- Finds the controllers and sets an interceptor on each one -->
    <bean class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping">
     <property name="interceptors">
         <list>
             <bean class="com.onebigplanet.web.interceptor.PortalInterceptor"/>    
         </list>
     </property>
    </bean> 

    <!-- METHOD HANDLER ADAPTER --> 
    <!-- Finds mapping of url through annotation on methods of Controller -->
    <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
        <property name="cacheSeconds" value="0"/>
        <property name="webBindingInitializer">
            <bean class="com.onebigplanet.web.binder.WebBindingInitializer"/>
        </property>
    </bean> 
</beans>

applicationContext-service.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans> 
    <!-- Declares a bunch of bean post-processors -->
    <context:annotation-config/>

    <context:component-scan base-package="com.onebigplanet.service.impl,com.onebigplanet.dao.impl.mysql" annotation-config="false"/> 

    <!-- Property configurer -->
    <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
     <property name="location" value="/WEB-INF/obp-service.properties" />
    </bean> 

    <!-- Post-processor for @Aspect annotated beans, which converts them into AOP advice -->
    <bean class="org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator"/>

    <!-- An @Aspect bean that converts exceptions thrown in service implementation classes to runtime exceptions  -->
    <bean id="exceptionAdvisor" class="com.onebigplanet.service.advisor.ExceptionAdvisor"/>
    <bean id="cachingAdvisor" class="com.onebigplanet.service.advisor.CacheAdvisor"/> 
    <bean id="businessIntelligenceAffiliateAdvisor" class="com.onebigplanet.service.advisor.BusinessIntelligenceAffiliateAdvisor"/>

    <!-- Writable datasource -->
    <jee:jndi-lookup id="dataSource" jndi-name="java:/ObpDS"/>

    <!-- ReadOnly datasource -->
    <jee:jndi-lookup id="readOnlyDataSource" jndi-name="java:/ObpReadOnlyDS"/> 

    <!-- Map the transaction manager to allow easy lookup of a UserTransaction -->
    <bean id="transactionManager" class="org.springframework.transaction.jta.JtaTransactionManager"/>

    <!-- Annotation driven transaction management -->
    <tx:annotation-driven transaction-manager="transactionManager"/>
</beans>

applicationContext-test.xml This is only included when running the unit tests. It's purpose is to overwrite some of the beans declared in the other config files.

<?xml version="1.0" encoding="UTF-8"?>
<beans>         
    <!-- Overwrite the property configurer bean such that it reads the test properties file instead -->
    <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
     <property name="location" value="/obp-test.properties"/>
    </bean> 

    <!-- All DAOs should use the test datasource -->
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
     <property name="driverClassName" value="${testDataSource.driverClassName}"/>
     <property name="url" value="${testDataSource.url}"/>
     <property name="username" value="${testDataSource.username}"/>
     <property name="password" value="${testDataSource.password}"/>
    </bean>

    <bean id="readOnlyDataSource" class="org.apache.commons.dbcp.BasicDataSource">
     <property name="driverClassName" value="${testDataSource.driverClassName}"/>
     <property name="url" value="${testDataSource.url}"/>
     <property name="username" value="${testDataSource.username}"/>
     <property name="password" value="${testDataSource.password}"/>
    </bean>

    <!-- 
     Overwrite the JTA transaction manager bean defined in applicationContent-service.xml with this one because
     the implementation of the former is provided by JBoss
    -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
     <property name="dataSource" ref="dataSource" />
    </bean>
<beans>

Answer 1

Sounds like you're referencing an implementation class instead of an interface. There is an excerpt here with more detail.

A Spring forum post: "Mixing JDK and CGLIB proxies"

A great blog post explaining pros and cons of JDK vs. CGLIB proxies.

Answer 2

Hey Jean, CGLib proxies are created by subclassing the class to be proxied -- you're attempting to proxy another proxy which isn't allowed since proxies are themselves final classes. Hence:

Caused by: java.lang.IllegalArgumentException: Cannot subclass final class class $Proxy25

Answer 3

I don't know if the solution was already shared and I am also sure the original requester must have found a solution, since it is a one year old query. For public interest however let me mention it here. Spring was using CGLIB because of the following declaration.

<!-- Post-processor for @Aspect annotated beans, which converts them into AOP advice --> 
<bean class="org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator">
      <property name="proxyTargetClass" value="true"/>
</bean>

The property should be set to false, so that the CGLIB is not triggered instead JDK Dynamic Proxying.

<property name="proxyTargetClass" value="false"/>

Hope that helps.