We are going to do small program using Spring Framework to study the basics of the Aspect-Oriented Programming
In this example I will create simple Java Console application
You will need aspectjrt.jar, aspectjweaver.jar and spring-aop.jar file for this application in addition to basic Spring jar file.
First you can create the Car bean class
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package com.kayak; import org.springframework.stereotype.Component; @Component public class Car { private String name; public void setName(String name) { this.name = name; } public String getName() { return "Audi "; } } |
I have used @Component annotation to make this class as Spring Bean
Next I will create Log class with show method and this show method will be called before the getName() is called
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package com.kayak; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Before; import org.springframework.context.annotation.EnableAspectJAutoProxy; import org.springframework.stereotype.Component; @Component @Aspect @EnableAspectJAutoProxy public class Log { @Before("execution(* com.kayak.Car.getName(..))") public void show(){ System.out.println("Log Method Show"); } } |
You have @Aspect and @EnableAspectJAutoProxy annotation which we need for Aspect Orined Programming.
@Before("execution(* com.kayak.Car.getName(..))") code tells to spring ececute the show method before calling the getName() of the Car class
So to run above code you can use the following main method
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package com.kayak; import org.springframework.context.ApplicationContext; import org.springframework.context.annotation.AnnotationConfigApplicationContext; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration; @Configuration @ComponentScan public class Test { public static void main(String[] args) { //ApplicationContext ctx = new ClassPathXmlApplicationContext("bean.xml"); ApplicationContext ctx = new AnnotationConfigApplicationContext(Test.class); Car car=ctx.getBean(Car.class); System.out.println(car.getName()); } } |
So you will get the following output
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run: Feb 19, 2018 5:39:34 PM org.springframework.context.annotation.AnnotationConfigApplicationContext prepareRefresh INFO: Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@21b8d17c: startup date [Mon Feb 19 17:39:34 IST 2018]; root of context hierarchy Log Method Show Audi BUILD SUCCESSFUL (total time: 3 seconds) |