Dout in Around Advice

[Satyajeet Kadam]

Code containing the Aspect

/*
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 * and open the template in the editor.
 */
package com.Kogeny;

import org.aspectj.lang.annotation.*;

/**
 *
 * @author satyajeet
 */
@Aspect
public class Asp {

    @Before("execution(* Code.display(..))")
    private void mainmethod() {
        System.out.println("ABC");

    }

    @After("execution(* Code.display(..))")
    private void mymethod() {
        System.out.println("DEF");

    }

  /*  @Around  ("execution(* Code.display(..))")
    private void mymethoda() {
        System.out.println("SSSS");

    }*/


}

Bean on which Aspect will be applied

/*
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 * and open the template in the editor.
 */

package com.Kogeny;

/**
 *
 * @author satyajeet
 */
public class Code {

    public void display()
    {
            System.out.println("Hello World");
    }

}

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package com.Kogeny;

/**
 *
 * @author satyajeet
 */
import org.springframework.context.support.*;
import org.springframework.context.*;

public class Main {

    public static void main(String args[]) {
        ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");
        Code ref = (Code) ctx.getBean("id");
        ref.display();


    }
}

<?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:p="http://www.springframework.org/schema/p"
	xmlns:aop="http://www.springframework.org/schema/aop"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd">

<aop:aspectj-autoproxy></aop:aspectj-autoproxy>
<bean id="name" class="com.Kogeny.Asp"/>
<bean id="id" class="com.Kogeny.Code"/>
<bean class="com.Kogeny.Main"/>

</beans>

After Running the above program i get the output as :

ABC
Hello World
DEF

After removing the comment from last method from class Asp i get the output as:

ABC
SSSS

Q1) I am not able to understand second output? why DEF and Hello world is not getting printed?

[Mark Spritzler]

Because with an Around type advice. You are required to call the target method. You do that by the following

@Around  ("execution(* Code.display(..))") 
private void mymethoda(ProceedingJoinPoint point) { 
    System.out.println("SSSS"); 
    point.proceed();
}

Without the call to proceed() the other objects won't get called. Also in Around if the target method returns an object, you have to return it from the Around method, otherwise the client will always get null. Around is the most powerful advice type, but with power comes great responsibility. Have fun

Mark