Not able to test AOP using AspectJ

[Niranjan Deshpande]

Hi all,

I am trying to use the auto proxying feature of Spring AOP. There are two ways to do it

1. using the basic auto proxying
2. using @AspectJ Annotation.

I tried running sample code for both, and could not see the auto prozying feature for both. But I am concentrating only on the way 2.

Here are the relevant code fragments:

The XML, the AOP part of it:

<aop:aspectj-autoproxy/>
<bean id="kenny" class="com.springinaction.springidol.Instrumentalist">
    <property name="song" value="Jingle Bells"/>
    <property name="stage" ref="theStage"/>
    <property name="instrument" ref="saxophone" />
</bean>
<bean id="saxophone" class="com.springinaction.springidol.Saxophone" />
<bean id="theStage" class="com.springinaction.springidol.Stage" factory-method="getInstance" />

The Java Classes:

package com.springinaction.springidol;
 
public class Saxophone implements Instrument {

public Saxophone() {}

public void play() {
System.out.println("TOOT TOOT TOOT");
}
 
public void clean() {
System.out.println("Cleaning : " + this.toString());
}
 
public void tune() {
System.out.println("Tuning :" + this.toString());

}

public String toString() {
return this.getClass().getSimpleName();
}
}

package com.springinaction.springidol;
 
public interface Instrument {
void play();

void tune();

void clean();
 
}

package com.springinaction.springidol;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.AfterThrowing;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
 
@Aspect
public class AudienceAspect {

public AudienceAspect() {}
@Pointcut("execution(* *.perform(..))")
public void performance() {}
 
@Before("performance()")
public void takeSeats() {
System.out.println("THE AUDIENCE IS TAKING THEIR SEATS.");
}
@Before("performance()")
public void turnOffCellPhones() {
System.out.println("THE AUDIENCE IS TURNIG OFF THEIR CELL PHONES");
}

@AfterReturning("performance()")
public void applaud() {
System.out.println("CLAP CLAP CLAP CLAP CLAP");
}

@AfterThrowing("performance()")
public void demandRefund() {
System.out.println("BOO WE WANT OUR MONEY BACK!");
}
}

I am using a plain java application that gets bean and uses them as:

XmlBeanFactory factory =
new XmlBeanFactory(new FileSystemResource("./src/spring-idol.xml"));
Performer performer1 = (Performer) factory.getBean("kenny");
performer1.perform();

The code for the Performer Interface:
package com.springinaction.springidol;

public interface Performer {
void perform() throws Exception; //PerformanceException;
}

When I run the application, I get to see only tthe sys outs of the Instrumentalist class and the Saxophone class. This shows that the functionality of the aspect is not associated with the bean. Am I missing something?

The code for Instrumentalist class

package com.springinaction.springidol;

import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;



public class Instrumentalist implements Performer, InitializingBean, DisposableBean {
private String song;
private Instrument instrument;
private Stage stage;

public Instrumentalist() {}

public void perform() throws Exception {//PerformanceException
System.out.print("Playing " + song + " : ");
instrument.play();
}

public void setSong(String song) {
this.song = song;
}

public void setInstrument(Instrument instrument) {
this.instrument = instrument;
}

public Stage getStage() {
return stage;
}

public void setStage(Stage stage) {
this.stage = stage;
}

public void tuneInstrument() {
instrument.tune();
}
public void cleanInstrument() {
instrument.clean();
}

public void afterPropertiesSet() throws Exception {
instrument.tune();

}

public void destroy() throws Exception {
instrument.clean();
}
}

[Christophe Verré]

From what I understand, any bean defined in the application context with the @AspectJ annotation will be detected by Spring. So unless the AudienceAspect is loaded, I don't think Spring will know about it. Please try the following :

1. Add the @AspectJ annotated bean in the context file

<bean id="audienceAspect" class="com.springinaction.springidol.AudienceAspect"/>

2. Use the ApplicationContext, so that your beans will be loaded by Spring

public static void main(String[] args) {
try {
ApplicationContext context = new FileSystemXmlApplicationContext("./src/spring-idol.xml");
Performer performer1 = (Performer) context.getBean("kenny");
performer1.perform();
} catch( Exception e ) {
e.printStackTrace();
}

[ February 29, 2008: Message edited by: Christophe Verre ]

[Niranjan Deshpande]

Hi,

Thanks a lot, the code is working as desired.

I agree with you on point1. The advice bean was not declared in my xml file.
I declared it.

But I did not get point 2. Why did XMLBeanFactory failed to work? Please explain.

[Christophe Verré]

A BeanFactory instantiates beans only when needed, so the advice will not be instantiated unless you explicitly load it, or reference it in an other loaded bean. On the contrary, an ApplicationContext instantiates all beans, unless you explicitly tell Spring not to.

[Niranjan Deshpande]

Thanks a lot Christophe.

I think I have tried all the four ways of AOP in Spring. But as said, the aop:config seems most convinient and easy to use.