Common AspectJ annotations :

1. @Before – Run before the method execution
2. @After – Run after the method returned a result
3. @AfterReturning – Run after the method returned a result, intercept the returned result as well.
4. @AfterThrowing – Run after the method throws an exception
5. @Around – Run around the method execution, combine all three advices above.

1. Directory Structure

See directory structure of this example.

2. Project Dependencies

To enable AspectJ, you need aspectjrt.jar, aspectjweaver.jar and spring-aop.jar. See following Maven pom.xml file.

File : pom.xml

<project ...>

	<properties>
		<spring.version>3.0.5.RELEASE</spring.version>
	</properties>

	<dependencies>

		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-core</artifactId>
			<version>${spring.version}</version>
		</dependency>

		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-context</artifactId>
			<version>${spring.version}</version>
		</dependency>

		<!-- Spring AOP + AspectJ -->
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-aop</artifactId>
			<version>${spring.version}</version>
		</dependency>

		<dependency>
			<groupId>org.aspectj</groupId>
			<artifactId>aspectjrt</artifactId>
			<version>1.6.11</version>
		</dependency>

		<dependency>
			<groupId>org.aspectj</groupId>
			<artifactId>aspectjweaver</artifactId>
			<version>1.6.11</version>
		</dependency>

	</dependencies>
</project>

3. Spring Beans

Normal bean, with few methods, later intercept it via AspectJ annotation.

package com.mkyong.customer.bo;

public interface CustomerBo {

	void addCustomer();

	String addCustomerReturnValue();

	void addCustomerThrowException() throws Exception;

	void addCustomerAround(String name);
}

package com.mkyong.customer.bo.impl;

import com.mkyong.customer.bo.CustomerBo;

public class CustomerBoImpl implements CustomerBo {

	public void addCustomer(){
		System.out.println("addCustomer() is running ");
	}

	public String addCustomerReturnValue(){
		System.out.println("addCustomerReturnValue() is running ");
		return "abc";
	}

	public void addCustomerThrowException() throws Exception {
		System.out.println("addCustomerThrowException() is running ");
		throw new Exception("Generic Error");
	}

	public void addCustomerAround(String name){
		System.out.println("addCustomerAround() is running, args : " + name);
	}
}

4. Enable AspectJ

In Spring configuration file, put “<aop:aspectj-autoproxy />“, and define your Aspect (interceptor) and normal bean.

File : Spring-Customer.xml

<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-3.0.xsd
	http://www.springframework.org/schema/aop
	http://www.springframework.org/schema/aop/spring-aop-3.0.xsd ">

	<aop:aspectj-autoproxy />

	<bean id="customerBo" class="com.mkyong.customer.bo.impl.CustomerBoImpl" />

	<!-- Aspect -->
	<bean id="logAspect" class="com.mkyong.aspect.LoggingAspect" />

</beans>

4. AspectJ @Before

In below example, the logBefore() method will be executed before the execution of customerBo interface,addCustomer() method.

File : LoggingAspect.java

package com.mkyong.aspect;

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

@Aspect
public class LoggingAspect {

	@Before("execution(* com.mkyong.customer.bo.CustomerBo.addCustomer(..))")
	public void logBefore(JoinPoint joinPoint) {

		System.out.println("logBefore() is running!");
		System.out.println("hijacked : " + joinPoint.getSignature().getName());
		System.out.println("******");
	}

}

Run it

CustomerBo customer = (CustomerBo) appContext.getBean("customerBo");
customer.addCustomer();

Output

logBefore() is running!
hijacked : addCustomer
******
addCustomer() is running

5. AspectJ @After

In below example, the logAfter() method will be executed after the execution of customerBo interface, addCustomer()method.

File : LoggingAspect.java

package com.mkyong.aspect;

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

@Aspect
public class LoggingAspect {

	@After("execution(* com.mkyong.customer.bo.CustomerBo.addCustomer(..))")
	public void logAfter(JoinPoint joinPoint) {

		System.out.println("logAfter() is running!");
		System.out.println("hijacked : " + joinPoint.getSignature().getName());
		System.out.println("******");

	}

}

Run it

CustomerBo customer = (CustomerBo) appContext.getBean("customerBo");
customer.addCustomer();

Output

addCustomer() is running
logAfter() is running!
hijacked : addCustomer
******

6. AspectJ @AfterReturning

In below example, the logAfterReturning() method will be executed after the execution of customerBo interface,addCustomerReturnValue() method. In addition, you can intercept the returned value with the “returning” attribute.

To intercept returned value, the value of the “returning” attribute (result) need to be same with the method parameter (result).

File : LoggingAspect.java

package com.mkyong.aspect;

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

@Aspect
public class LoggingAspect {

   @AfterReturning(
      pointcut = "execution(* com.mkyong.customer.bo.CustomerBo.addCustomerReturnValue(..))",
      returning= "result")
   public void logAfterReturning(JoinPoint joinPoint, Object result) {

	System.out.println("logAfterReturning() is running!");
	System.out.println("hijacked : " + joinPoint.getSignature().getName());
	System.out.println("Method returned value is : " + result);
	System.out.println("******");

   }

}

Run it

CustomerBo customer = (CustomerBo) appContext.getBean("customerBo");
customer.addCustomerReturnValue();

Output

addCustomerReturnValue() is running
logAfterReturning() is running!
hijacked : addCustomerReturnValue
Method returned value is : abc
******

7. AspectJ @AfterReturning

In below example, the logAfterThrowing() method will be executed if the customerBo interface,addCustomerThrowException() method is throwing an exception.

File : LoggingAspect.java

package com.mkyong.aspect;

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

@Aspect
public class LoggingAspect {

   @AfterThrowing(
      pointcut = "execution(* com.mkyong.customer.bo.CustomerBo.addCustomerThrowException(..))",
      throwing= "error")
    public void logAfterThrowing(JoinPoint joinPoint, Throwable error) {

	System.out.println("logAfterThrowing() is running!");
	System.out.println("hijacked : " + joinPoint.getSignature().getName());
	System.out.println("Exception : " + error);
	System.out.println("******");

    }
}

Run it

CustomerBo customer = (CustomerBo) appContext.getBean("customerBo");
customer.addCustomerThrowException();

Output

addCustomerThrowException() is running
logAfterThrowing() is running!
hijacked : addCustomerThrowException
Exception : java.lang.Exception: Generic Error
******
Exception in thread "main" java.lang.Exception: Generic Error
	//...

8. AspectJ @Around

In below example, the logAround() method will be executed before the customerBo interface, addCustomerAround()method, and you have to define the “joinPoint.proceed();” to control when should the interceptor return the control to the original addCustomerAround() method.

File : LoggingAspect.java

package com.mkyong.aspect;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Around;

@Aspect
public class LoggingAspect {

   @Around("execution(* com.mkyong.customer.bo.CustomerBo.addCustomerAround(..))")
   public void logAround(ProceedingJoinPoint joinPoint) throws Throwable {

	System.out.println("logAround() is running!");
	System.out.println("hijacked method : " + joinPoint.getSignature().getName());
	System.out.println("hijacked arguments : " + Arrays.toString(joinPoint.getArgs()));

	System.out.println("Around before is running!");
	joinPoint.proceed(); //continue on the intercepted method
	System.out.println("Around after is running!");

	System.out.println("******");

   }

}

Run it

CustomerBo customer = (CustomerBo) appContext.getBean("customerBo");
customer.addCustomerAround("mkyong");

Output

logAround() is running!
hijacked method : addCustomerAround
hijacked arguments : [mkyong]
Around before is running!
addCustomerAround() is running, args : mkyong
Around after is running!
******

Conclusion

It’s always recommended to apply the least power AsjectJ annotation. It’s rather long article about AspectJ in Spring. for further explanations and examples, please visit the reference links below.