SPRING in ACTION 4th Note-chapter fourth aspect-oriented spring-010-introduction adding new methods to classes

One

The role of 1.Introduction is to increase the dynamic method of the class

When Spring discovers a beans annotated with @Aspect, it'll automatically create a proxy that delegates calls to either The proxied bean or to the introduction implementation, depending on whether the method called belongs to the proxied bean Or to the introduced interface.

Ii. examples

To add encore functionality to performers

1.

 Package Concert;  Public Interface Performance {  void  performance ();}

2.

1  PackageConcert;2 3 Importorg.springframework.stereotype.Component;4 5 @Component6  Public classEminemImplementsperformance{7 8 @Override9      Public voidperformance () {TenSystem.out.println ("You can do anything set to your mind"); One     } A  -}

3.

 Package Concert;  Public Interface encoreable {    void  performencore ();}

4.

1  PackageConcert;2 3  Public classDefaultencoreableImplementsencoreable{4 5 @Override6      Public voidPerformencore () {7System.out.println ("Defaultencoreable---> Performencore ()");8     }9 Ten}

5.

1  PackageConcert;2 3 ImportOrg.aspectj.lang.annotation.Aspect;4 Importorg.aspectj.lang.annotation.DeclareParents;5 Importorg.springframework.stereotype.Component;6 7 @Aspect8 @Component9  Public classEncoreableintroducer {Ten@DeclareParents (value = "concert. Performance+ ", Defaultimpl = defaultencoreable.class) One      Public Staticencoreable encoreable; A}

Analytical:

The role of @DeclareParents is to introduce "encoreable" to "performance", which consists of three parts

(1) Value: The interface type of the bean to add new functionality

(2) Defaultimpl: the implementation of the function interface to be added

(3) Added static variable of the function interface

6. Configuration Files

 Package Concert; Import Org.springframework.context.annotation.ComponentScan; Import org.springframework.context.annotation.Configuration; Import org.springframework.context.annotation.enableaspectjautoproxy;@ Configuration@componentscan@enableaspectjautoproxypublicclass  Config {}

7. Testing

1 Importorg.junit.Test;2 ImportOrg.junit.runner.RunWith;3 Importorg.springframework.beans.factory.annotation.Autowired;4 ImportOrg.springframework.context.ApplicationContext;5 Importorg.springframework.test.context.ContextConfiguration;6 ImportOrg.springframework.test.context.junit4.SpringJUnit4ClassRunner;7 8 Importconcert. Config;9 Importconcert. encoreable;Ten  One@RunWith (Springjunit4classrunner.class) A@ContextConfiguration (Classes=config.class) -  Public classIntroductiontest { - @Autowired the ApplicationContext context; -  - @Test -    Public voideddieshouldbeacontestant () { +encoreable Eminem = (encoreable) Context.getbean ("Eminem"); - Eminem.performencore (); + //Performance Eminem = (performance) Context.getbean ("Eminem"); A //eminem.performance (); at   } -}

In addition: The configuration method of XML:

1<?xml version= "1.0" encoding= "UTF-8"?>2<beans xmlns= "Http://www.springframework.org/schema/beans"3Xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance"4xmlns:aop= "HTTP://WWW.SPRINGFRAMEWORK.ORG/SCHEMA/AOP"5Xsi:schemalocation= "Http://www.springframework.org/schema/beans6http//www.springframework.org/schema/beans/spring-beans.xsd7http//WWW.SPRINGFRAMEWORK.ORG/SCHEMA/AOP8http//www.springframework.org/schema/aop/spring-aop.xsd ">9 Ten<bean id= "Eddie" One       class= "Com.springinaction.springidol.Instrumentalist" > A<property name= "Instrument" > -<beanclass= "Com.springinaction.springidol.Guitar"/> -</property> the</bean> -  -<!--<start id= "Audience_bean"/>--> -<bean id= "Audience" +       class= "Com.springinaction.springidol.Audience"/> -<!--<end id= "Audience_bean"/>--> +  A<!--<start id= "Audience_aspect"/>--> at<aop:config> -<aop:aspect ref= "Audience" > -<aop:pointcut id= "Performance" expression= -"Execution (* com.springinaction.springidol.Performer.perform (..))" -/> -<Aop:before inpointcut-ref= "Performance" -Method= "Takeseats ()"/> to<Aop:before +pointcut-ref= "Performance" -method= "Turnoffcellphones"/> the<aop:after-returning *pointcut-ref= "Performance" $Method= "Applaud"/>Panax Notoginseng<aop:after-throwing -pointcut-ref= "Performance" themethod= "Demandrefund"/> +</aop:aspect> A      the<!--<start id= "Contestant_introduction"/>--> +<aop:aspect> -<aop:declare-Parents $Types-matching= "com.springinaction.springidol.performer+" $implement-Interface= "Com.springinaction.springidol.Contestant" -     default-impl= "Com.springinaction.springidol.GraciousContestant" -/> the</aop:aspect> -<!--<end id= "Contestant_introduction"/>-->Wuyi  the<!-- -<start id= "Delegate_ref"/> Wu<aop:declare-Parents -Types-matching= "com.springinaction.springidol.performer+" Aboutimplement-Interface= "Com.springinaction.springidol.Contestant" $delegate-ref= "Contestantdelegate" -/> -<end id= "Delegate_ref"/> -  A<start id= "Contestant_delegate"/> +<bean id= "Contestantdelegate" the     class= "Com.springinaction.springidol.GraciousContestant"/> -<end id= "Contestant_delegate"/> $  the- the      the</aop:config> the<!--<end id= "Audience_aspect"/>--> -  in</beans>

SPRING in ACTION 4th Note-chapter fourth aspect-oriented spring-010-introduction adding new methods to classes