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How to implement After Throwing Advice using @AspectJ Annotation-Driven AOP in Java ?.

A simple application to demonstrate how to implement After Throwing Advice using @AspectJ Annotation-Driven AOP in Java.

Step 1:- Create a Interface Divide.java

package com.hubberspot.aspectj.annotation.afterthrowingadvice;

// Its a simple interface for the Division service.
// It contains one single method called as divide().
// This method takes in two arguments both of the type
// int.

public interface Divide {

 public int divide(int a , int b);

}



Step 2:- DivisionImpl.java Service Implementation Class

package com.hubberspot.aspectj.annotation.afterthrowingadvice;

// It is the implementation class for the 
// Division service. It just calculates and returns 
// division of two numbers passed to it as arguments.
// If denominator passed to it as zero than 
// new ArithmeticException() is thrown.

public class DivideImpl implements Divide {

 @Override
 public int divide(int a, int b) {

  if(b != 0) {

   return a/b;

  }

  else {

   throw new ArithmeticException();

  }

 }

}



Step 3:- After Throwing Advice Implementation class

package com.hubberspot.aspectj.annotation.afterthrowingadvice;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.AfterThrowing;
import org.aspectj.lang.annotation.Aspect;

//@Aspect annotation treats this Java class as 
//Aspect. Its not ordinary POJO class.

@Aspect
public class AfterThrowingDivideAdvice {

 // Method afterThrowing() is a After Throwing advice
 // implemented by providing @AfterThrowing annotation.
 // This annotation takes in Pointcut expression, which 
 // indicates when this advice executes.
 // This Pointcut expression tells that afterThrowing() advice
 // will execute after any exception is thrown from the method 
 // divide of Divide interface.
 // The after advice takes in JoinPoint and an Object. JoinPoint 
 // which here represents method execution and pointcut expression
 // takes in throwing property and makes it able to store, available 
 // to the afterThrowing method.

 @AfterThrowing ( 
   pointcut = "execution(* com.hubberspot.aspectj.annotation.afterthrowingadvice.Divide.divide(..))"
   , throwing = "exception" )
 public void afterThrowing(JoinPoint joinPoint , Throwable exception) {

  System.out.println("Exception is thrown by divide method : "+ exception);

 }
}






Step 4 :- Spring Configuration file


<?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"
 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">

  <aop:aspectj-autoproxy></aop:aspectj-autoproxy>

  <!-- Implementation Class -->
    <bean id="divide"
 class="com.hubberspot.aspectj.annotation.afterthrowingadvice.DivideImpl" />

    <bean id="afterThrowingAdvice"
 class="com.hubberspot.aspectj.annotation.afterthrowingadvice.AfterThrowingDivideAdvice" />

</beans>



Step 5:- Test class

package com.hubberspot.aspectj.annotation.afterthrowingadvice;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class DivisionTest {

 public static void main(String[] args) {

  // ApplicationContext is a Spring interface which 
  // provides with the configuration for an application. 
  // It provides us with all the methods that BeanFactory 
  // provides. It loads the file resources in a older 
  // and generic manner. It helps us to publish events to the
  // listener registered to it. It also provides quick support
  // for internationalization. It provides us with the object 
  // requested, it reads the configuration file and provides
  // us with the necessary object required.
  // We are using concrete implementation of AbstractApplicationContext
  // here called as ClassPathXmlApplicationContext because this 
  // bean factory reads the xml file placed in the classpath of 
  // our application. We provide ClassPathXmlApplicationContext
  // with a configuration file called as after_throwing_advice.xml placed
  // at classpath of our application.


  ApplicationContext context = 
    new ClassPathXmlApplicationContext("after_throwing_advice.xml");

  // In order to get a object instantiated for a particular bean 
  // we call getBean() method of ClassPathXmlApplicationContext
  // passing it the id for which the object is to be needed. 
  // Here getBean() returns an Object. We need to cast it back 
  // to the Divide object. Without implementing new keyword we 
  // have injected object of Divide just by reading an xml 
  // configuration file.

  Divide divide = (Divide)context.getBean("divide");

  int result = divide.divide(10 , 5);

  System.out.println("Result = " + result);

  result = divide.divide(10, 0);

  System.out.println("Result = " + result);


 }

}


Output of the program : 


 
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