AOP Implementation using MethodBeforeAdvice

Audience.java:

package com.lnn.advice;

public class Audience {

      public Audience() {

      }

      public void takeSeats() {

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

      }

      public void turnOffCellPhones() {

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

      }

      public void applaud() {

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

      }

      public void demandRefund() {

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

      }

}

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;

      }

}

BeforeAdvice.java:

package com.lnn.advice.before;

import java.lang.reflect.Method;

import org.springframework.aop.MethodBeforeAdvice;

import com.lnn.advice.Audience;

public class BeforeAdvice implements MethodBeforeAdvice {

      private Audience audience;

      public void setAudience(Audience audience) {

            this.audience = audience;

      }

      @Override

      public void before(Method arg0, Object[] arg1, Object arg2) throws Throwable {

            audience.takeSeats();

            audience.turnOffCellPhones();

      }

}

before.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="instrumentalist" class="com.lnn.advice.Instrumentalist">

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

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

      </bean>

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

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

      <bean id="audienceAdvice" class="com.lnn.advice.before.BeforeAdvice">

            <property name="audience" ref="audience" />

      </bean>

      <bean id="performancePointcut" class="org.springframework.aop.support.JdkRegexpMethodPointcut">

            <property name="pattern" value=".*perform" />

      </bean>

      <bean id="audienceAdvisor" class="org.springframework.aop.support.DefaultPointcutAdvisor">

            <property name="advice" ref="audienceAdvice" />

            <property name="pointcut" ref="performancePointcut" />

      </bean>

      <bean id="instrumentalistproxy" class="org.springframework.aop.framework.ProxyFactoryBean">

            <property name="target" ref="instrumentalist" />

            <property name="interceptorNames" value="audienceAdvisor" />

            <property name="proxyInterfaces" value="com.lnn.advice.Performer" />

      </bean>

</beans>

Test.java:

package com.lnn.advice.before;

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/before.xml");

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

            performer.perform();

      }

}