Spring expression language not working with spring aop

Question

<bean id="eddie" class="com.springinaction.Instrumentalist">
    <property name="instrument" value="#{violin}"></property>
    <property name="song" value="#{kenny.song}"></property>

</bean>

<bean id="violin" class="com.springinaction.Violin">
</bean>


<bean id="kenny" class="com.springinaction.Instrumentalist">
    <property name="song" value="Kenny is a star,kenny is a star"></property>
    <property name="instrument" ref="saxopone"></property>
</bean>

<aop:config>

    <aop:aspect ref="audience">

        <aop:before pointcut="execution(* com.springinaction.Performer.perform(..))" method="takeSeats()"/>

        <aop:after-throwing method="demandRefund" pointcut="execution(* com.springinaction.Performer.perform(..))"/>

    </aop:aspect>

</aop:config>

In the above code,I am injecting song , instrument property of eddie bean using spring expression language. But, song property not injected properly..and i am getting the below error:

Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'eddie' defined in class path resource [spring-config.xml]: Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanExpressionException: Expression parsing failed; nested exception is org.springframework.expression.spel.SpelEvaluationException: EL1008E:(pos 6): Field or property 'song' cannot be found on object of type '$Proxy4' at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:450) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:290) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:287) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:189) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:557) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:842) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:416) at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:139) at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:83) at com.springinaction.Main.main(Main.java:10)

Instrument property is injected properly where as song property is not injected and this is happening because of aop only..

when i comment out <aop:config> it is working fine..

Anything wrong?

Answer 1

Did you try

<aop:config proxy-target-class="true">
...
</aop:config>

This way you get a dynamic subclass and the property should be available in the proxy created via Spring AOP.

The default behaviour of Spring AOP is to create a Java proxy for the interfaces, so the properties of any classes won't be accessible through the proxy.