Introducing new functionality with Spring AOP
I am learning Spring using the Spring In Action (Edition 3) book. I have come across an example in the book thats not working for me. Following is the detail:
I am trying to use Spring AOP to introduce new functionality in a bean:
Here is the class structure:
- Instrumentalist implements Performer
- GraciousContestant implements Contestant
Performer interface
public interface Performer {
void perform();
}
Class Instrumentalist
package chapter4;
public class Instrmentalist implements Performer {
public void perform() {
System.out.println("Sining hey hey, hey");
}
}
Contestant Interface
package chapter4;
public interface Contestant {
void receiveAward();
}
GraciousContestant Class
package chapter4;
public class GraciousContestant implements Contestant {
public void receiveAward() {
System.out.println("Won a car worth 4K!");
}
}
My spring configuaration file called "spring-idol2.xml" is as below:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.1.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd">
<bean id="ken" class="chapter4.Instrmentalist" />
<bean id="contestantDelegate" class="chapter4.GraciousContestant" />
<aop:config>
<aop:aspect>
<aop:declare-parents
types-matching="chapter4.Performer+"
implement-interface="chapter4.Contestant"
delegate-ref="contestantDelegate"/>
</aop:aspect>
<aop:aspect ref="ken">
<aop:pointcut id="performance"
expression="execution(* chapter4.Performer.perform(..))" />
<aop:after pointcut-ref="performance" method="receiveAward"/>
</aop:aspect>
</aop:config>
</beans>
My Main method looks like this:
package chapter4;
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class TestMain {
public static void main(String[] args) {
AbstractApplicationContext context =
new ClassPathXmlApplicationContext("/chapter4/spring-idol2.xml");
Performer p1 = (Performer) context.getBean("ken");
p1.perform();
}
}
What is supposed to be printed out is as follows:
Sining hey hey, hey
Won a car worth 4K!
However I get the following error:
Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'ken' defined in class path resource [chapter4/spring-idol2.xml]: BeanPostProcessor before instantiation of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.aop.aspectj.DeclareParentsAdvisor#0': Cannot resolve reference to bean 'contestantDelegate' while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'contestantDelegate' defined in class path resource [chapter4/spring-idol2.xml]: BeanPostProcessor before instantiation of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.aop.aspectj.AspectJPointcutAdvisor#0': Cannot create inner bean '(inner bean)' of type [org.springframework.aop.aspectj.AspectJAfterAdvice] while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)': Cannot create inner bean '(inner bean)' of type [org.springframework.aop.config.MethodLocatingFactoryBean] while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)': Initialization of bean failed; nested exception is java.lang.IllegalArgumentException: Unable to locate method [receiveAward] on bean [ken]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:452)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:295)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:580)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:900)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:455)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)
at chapter4.TestMain.main(TestMain.java:13)
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.aop.aspectj.DeclareParentsAdvisor#0': Cannot resolve reference to bean 'contestantDelegate' while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'contestantDelegate' defined in class path resource [chapter4/spring-idol2.xml]: BeanPostProcessor before instantiation of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.aop.aspectj.AspectJPointcutAdvisor#0': Cannot create inner bean '(inner bean)' of type [org.springframework.aop.aspectj.AspectJAfterAdvice] while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)': Cannot create inner bean '(inner bean)' of type [org.springframework.aop.config.MethodLocatingFactoryBean] while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)': Initialization of bean failed; nested exception is java.lang.IllegalArgumentException: Unable to locate method [receiveAward] on bean [ken]
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:328)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:106)
at org.springframework.beans.factory.support.ConstructorResolver.resolveConstructorArguments(ConstructorResolver.java:616)
at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:148)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1003)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:907)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:485)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:295)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:198)
at org.springframework.aop.framework.autoproxy.BeanFactoryAdvisorRetrievalHelper.findAdvisorBeans(BeanFactoryAdvisorRetrievalHelper.java:86)
at org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator.findCandidateAdvisors(AbstractAdvisorAutoProxyCreator.java:100)
at org.springframework.aop.aspectj.autoproxy.AspectJAwareAdvisorAutoProxyCreator.shouldSkip(AspectJAwareAdvisorAutoProxyCreator.java:107)
at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.postProcessBeforeInstantiation(AbstractAutoProxyCreator.java:278)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInstantiation(AbstractAutowireCapableBeanFactory.java:848)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.resolveBeforeInstantiation(AbstractAutowireCapableBeanFactory.java:820)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:446)
... 10 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'contestantDelegate' defined in class path resource [chapter4/spring-idol2.xml]: BeanPostProcessor before instantiation of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.aop.aspectj.AspectJPointcutAdvisor#0': Cannot create inner bean '(inner bean)' of type [org.springframework.aop.aspectj.AspectJAfterAdvice] while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)': Cannot create inner bean '(inner bean)' of type [org.springframework.aop.config.MethodLocatingFactoryBean] while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)': Initialization of bean failed; nested exception is java.lang.IllegalArgumentException: Unable to locate method [receiveAward] on bean [ken]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:452)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:295)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:322)
... 28 more
开发者_如何转开发Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.aop.aspectj.AspectJPointcutAdvisor#0': Cannot create inner bean '(inner bean)' of type [org.springframework.aop.aspectj.AspectJAfterAdvice] while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)': Cannot create inner bean '(inner bean)' of type [org.springframework.aop.config.MethodLocatingFactoryBean] while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)': Initialization of bean failed; nested exception is java.lang.IllegalArgumentException: Unable to locate method [receiveAward] on bean [ken]
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:281)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:125)
at org.springframework.beans.factory.support.ConstructorResolver.resolveConstructorArguments(ConstructorResolver.java:630)
at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:148)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1003)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:907)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:485)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:295)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:198)
at org.springframework.aop.framework.autoproxy.BeanFactoryAdvisorRetrievalHelper.findAdvisorBeans(BeanFactoryAdvisorRetrievalHelper.java:86)
at org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator.findCandidateAdvisors(AbstractAdvisorAutoProxyCreator.java:100)
at org.springframework.aop.aspectj.autoproxy.AspectJAwareAdvisorAutoProxyCreator.shouldSkip(AspectJAwareAdvisorAutoProxyCreator.java:107)
at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.postProcessBeforeInstantiation(AbstractAutoProxyCreator.java:278)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInstantiation(AbstractAutowireCapableBeanFactory.java:848)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.resolveBeforeInstantiation(AbstractAutowireCapableBeanFactory.java:820)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:446)
... 33 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)': Cannot create inner bean '(inner bean)' of type [org.springframework.aop.config.MethodLocatingFactoryBean] while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)': Initialization of bean failed; nested exception is java.lang.IllegalArgumentException: Unable to locate method [receiveAward] on bean [ken]
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:281)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:125)
at org.springframework.beans.factory.support.ConstructorResolver.resolveConstructorArguments(ConstructorResolver.java:616)
at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:148)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1003)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:907)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:485)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:270)
... 51 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)': Initialization of bean failed; nested exception is java.lang.IllegalArgumentException: Unable to locate method [receiveAward] on bean [ken]
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.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:270)
... 59 more
Caused by: java.lang.IllegalArgumentException: Unable to locate method [receiveAward] on bean [ken]
at org.springframework.aop.config.MethodLocatingFactoryBean.setBeanFactory(MethodLocatingFactoryBean.java:75)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeAwareMethods(AbstractAutowireCapableBeanFactory.java:1440)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1408)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
... 61 more
Could someone kindly explain to me why it says "Unable to locate method [receiveAward] on bean [ken]" even though I have declared a parent? Is the syntax wrong?
Thank you very much,
regards,
Khush.
Note that <aop:config> sees beans before aspects are applied, therefore I guess that you can't use methods introduced by <aop:declare-parents> in other aspect declarations.
If you want to check whether <aop:declare-parents> worked, you can do something like this:
Performer p1 = (Performer) context.getBean("ken");
p1.perform();
((Contestant) p1).reveiveAward();
I think when you write
<aop:aspect ref="ken">
...
</aop:aspect>
what you are saying is that the aspect is implemented in the bean named "ken". This is not the case in your example, the aspect is in the bean "contestantDelegate". So I would try with;
<aop:aspect ref="contestantDelegate">
...
</aop:aspect>
加载中,请稍侯......
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