Spring表达式语言不适用于spring aop(Spring expression language not working with spring aop)

Spring表达式语言不适用于spring aop(Spring expression language not working with spring aop) <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>

在上面的代码中，我使用spring表达式语言注入了eddie bean的song ， instrument属性。 但是， song属性没有正确注入..我得到以下错误：

线程“main”org.springframework.beans.factory.BeanCreationException中的异常：在类路径资源[spring-config.xml]中定义名称为'eddie'的bean时出错：bean的初始化失败; 嵌套异常是org.springframework.beans.factory.BeanExpressionException：表达式解析失败; 嵌套异常是org.springframework.expression.spel.SpelEvaluationException：EL1008E：（pos 6）：在org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory上的'$ Proxy4'类型的对象上找不到字段或属性'song'。 org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean（AbstractAutowireCapableBeanFactory.java:450）中的doCreateBean（AbstractAutowireCapableBeanFactory.java:519）位于org.springframework.beans.factory.support.AbstractBeanFactory $ 1.getObject（AbstractBeanFactory.java:290） ）org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton（DefaultSingletonBeanRegistry.java:222）位于org.springframework.beans的org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean（AbstractBeanFactory.java:287）。 factory.support.AbstractBeanFactory.getBean（AbstractBeanFactory.java:189）at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons（DefaultListableBeanFa） ctory.java:557）atg.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization（AbstractApplicationContext.java:842）位于org.springframework.context的org.springframework.context.support.AbstractApplicationContext.refresh（AbstractApplicationContext.java:416） .support.ClassPathXmlApplicationContext。（ClassPathXmlApplicationContext.java:139）位于com.springinaction.Main.main（Main.java:10）的org.springframework.context.support.ClassPathXmlApplicationContext。（ClassPathXmlApplicationContext.java:83）。

如果没有注入歌曲属性，则会正确注入乐器属性，因为只有aop才会发生这种情况。

当我评论<aop:config>它工作正常..

哪里不对了？

<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?

最满意答案

你试过了吗

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

这样您就可以获得动态子类，并且该属性应该在通过Spring AOP创建的代理中可用。

Spring AOP的默认行为是为接口创建Java代理，因此无法通过代理访问任何类的属性。

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.