AspectJ libraries provides the facility to declare aspect, pointcut etc with the help of annotations. Let us discuss the commonly used AspectJ annotations first.
Declaring an aspect:
The @Aspect annotation is used to declare a class as an aspect.
@Aspect public class AspectModule { } |
Declaring a pointcut:
The @Pointcut annotation is used to declare a pointcut. The expression parameter represents the expression used for matching the join point.
@Pointcut("execution(expression)") private void businessService() { //Block of code. } |
Declaring advices:
The @{ADVICE-NAME} annotations is used to declare an advice.
Advice types:
Before:
It executes before the method execution.
After:
It executes after the method execution. It not depends upon the method outcome.
after-returning:
It executes after the method execution when method completes successfully.
after-throwing:
It executes after the method execution when method exits by throwing an exception.
Around:
It executes before and after the advised method is called.
Spring AOP AspectJ Annotation Configuration Advice Example:
BusinessLogic.java
/** * This class will be used as a bean class. * @author javawithease */ public class BusinessLogic { public void implementBusinessLogic(){ System.out.println("Business logic executed."); } public String returnValue(){ System.out.println("Return value executed."); return "tutorialspointexamples.com"; } public void throwException(){ System.out.println("Business logic throw exception."); throw new ArithmeticException("Arithmetic exception occure."); } } |
AdviceTest.java
import org.aspectj.lang.annotation.After; 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 AdviceTest { @Pointcut("execution(* com.javawithease.business.*.*(..))") private void selectAll(){ } @Before("selectAll()") public void beforeAdvice(){ System.out.println("Before advice executed."); } @After("selectAll()") public void afterAdvice(){ System.out.println("After advice executed."); } @AfterReturning(pointcut = "selectAll()", returning="retVal") public void afterReturningAdvice(Object retVal){ System.out.println("After returning advice executed."); System.out.println("Returning value: " + retVal); } @AfterThrowing(pointcut = "selectAll()", throwing = "ex") public void afterThrowingAdvice(ArithmeticException ex){ System.out.println("Throwing advice executed."); System.out.println("Exception: " + ex.getMessage()); } } |
applicationContext.java
<?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-3.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd"> <aop:config> <aop:aspect id="log" ref="adviceTest"> <aop:pointcut id="selectAll" expression="execution(* com.javawithease.business.*.*(..))"/> <aop:before pointcut-ref="selectAll" method="beforeAdvice"/> <aop:after pointcut-ref="selectAll" method="afterAdvice"/> <aop:after-returning pointcut-ref="selectAll" returning="retVal" method="afterReturningAdvice"/> <aop:after-throwing pointcut-ref="selectAll" throwing="ex" method="afterThrowingAdvice"/> </aop:aspect> </aop:config> <bean id="businessLogic" class="com.javawithease.business.BusinessLogic"/> <bean id="adviceTest" class="com.javawithease.business.AdviceTest"/> </beans> |
Test.java
import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class Test { public static void main(String[] args) { //Get ApplicationContext using spring configuration file. ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml"); //Get BusinessLogic bean object from ApplicationContext instance. BusinessLogic businessLogic = (BusinessLogic) context.getBean("businessLogic"); //Call implementBusinessLogic method of BusinessLogic bean. businessLogic.implementBusinessLogic(); System.out.println("------------------------------------"); businessLogic.returnValue(); System.out.println("------------------------------------"); businessLogic.throwException(); } } |
Output:
Before advice executed. Business logic executed. After advice executed. After returning advice executed. Returning value: null ----------------------------------------- Before advice executed. Return value executed. After advice executed. After returning advice executed. Returning value: tutorialspointexamples.com ----------------------------------------- Before advice executed. Business logic throw exception. After advice executed. Throwing advice executed. Exception: Arithmetic exception occure. Exception in thread "main" java.lang.ArithmeticException: Arithmetic exception occure. at com.javawithease.business.BusinessLogic.throwException(BusinessLogic.java:19) at com.javawithease.business.BusinessLogic$$FastClassByCGLIB$$19ab96db.invoke(<generated>) at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:191) at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:692) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150) at org.springframework.aop.aspectj.AspectJAfterAdvice.invoke(AspectJAfterAdvice.java:42) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) at org.springframework.aop.framework.adapter.AfterReturningAdviceInterceptor.invoke(AfterReturningAdviceInterceptor.java:50) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) at org.springframework.aop.aspectj.AspectJAfterThrowingAdvice.invoke(AspectJAfterThrowingAdvice.java:55) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) at org.springframework.aop.framework.adapter.MethodBeforeAdviceInterceptor.invoke(MethodBeforeAdviceInterceptor.java:50) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:89) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:625) at com.javawithease.business.BusinessLogic$$EnhancerByCGLIB$$4299115d.throwException(<generated>) at com.javawithease.business.Test.main(Test.java:20) |
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