AOP implementation using annotations

Audience.java:

package com.lnn.advice.auto;

import org.aspectj.lang.ProceedingJoinPoint;

import org.aspectj.lang.annotation.AfterReturning;

import org.aspectj.lang.annotation.AfterThrowing;

import org.aspectj.lang.annotation.Around;

import org.aspectj.lang.annotation.Aspect;

import org.aspectj.lang.annotation.Before;

@Aspect

public class Audience {

      @Before("execution(* *.perform(..))")

      public void takeSeats() {

            System.out.println("The audience is taking their seats.");

      }

      @Before("execution(* *.perform(..))")

      public void turnOffCellPhones() {

            System.out.println("The audience is turning off their cellphones");

      }

      @AfterReturning("execution(* *.perform(..))")

      public void applaud() {

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

      }

      @AfterThrowing("execution(* *.perform(..))")

      public void demandRefund() {

            System.out.println("Boo! We want our money back!");

      }

      @Around("execution(* *.perform(..))")

      public void watchPerformance(ProceedingJoinPoint joinpoint) {

            try {

                  System.out.println("Before Method");

                  joinpoint.proceed();

                  System.out.println("After Return");

            } catch (Throwable e) {

                  System.out.println("After Throwing.");

            }

      }

}

Instrument.java:

package com.lnn.advice;

public interface Instrument {

      public void play();

}

Violin.java:

package com.lnn.advice;

public class Violin implements Instrument {

      @Override

      public void play() {

            System.out.println("violin is playing now...");

      }

}

PerformanceException:

package com.lnn.advice;

public class PerformanceException extends Exception {

      private static final long serialVersionUID = -6772609716850440380L;

     

}

Performer.java:

package com.lnn.advice;

public interface Performer {

      public void perform() throws PerformanceException;

}

Instrumentalist.java:

package com.lnn.advice;

import com.lnn.advice.Instrument;

import com.lnn.advice.PerformanceException;

import com.lnn.advice.Performer;

public class Instrumentalist implements Performer {

      public Instrumentalist() {

      }

      public void perform() throws PerformanceException {

            System.out.print("Playing " + song + " : ");

            if (instrument != null) {

                  instrument.play();

            } else {

                  throw new PerformanceException();

            }

      }

      private String song;

      public void setSong(String song) {

            this.song = song;

      }

      private Instrument instrument;

      public void setInstrument(Instrument instrument) {

            this.instrument = instrument;

      }

}

auto.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">

      <bean id="violin" class="com.lnn.advice.Violin" />

      <bean id="instrumentalist" class="com.lnn.advice.Instrumentalist">

            <property name="song" value="It's My Life" />

            <property name="instrument" ref="violin" />

      </bean>

      <bean id="audience" class="com.lnn.advice.auto.Audience" />

      <aop:aspectj-autoproxy/>        

</beans>

Test.java:

package com.lnn.advice.auto;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.lnn.advice.PerformanceException;

import com.lnn.advice.Performer;

public class Test {

      public static void main(String[] args) throws PerformanceException {

            ApplicationContext context = new ClassPathXmlApplicationContext("aop/auto.xml");

            Performer performer = (Performer) context.getBean("instrumentalist");

            performer.perform();

      }

}