SpringAOP:为目标类添加新的功能（拓展接口）

比如，原来的手机只能打电话，发短信。

现在，手机可以做为pad（掌上电脑），可以上网，看电影，打游戏。

但是，我不想去继承实现，我就要用AOP。

这次Aspect可就不同了

首先出场，基础类

package com.xbz.learn.spring.aspect.exspandMethod;

public interface Mobile {
/**
* 打电话
*/
public  void doCall();
}

package com.xbz.learn.spring.aspect.exspandMethod;

public interface Pad {
/**
* 做为电脑，可以看电影
*/
public void watchMovie();
}

package com.xbz.learn.spring.aspect.exspandMethod;

public class SampleMobile implements Mobile{

public void doCall() {
System.out.println("可以打电话");
}

}

package com.xbz.learn.spring.aspect.exspandMethod;

public class SamplePad implements Pad{

public void watchMovie() {
System.out.println("可以看电影");
}

}

闪亮登场，我们的主角：Aspect类

package com.xbz.learn.spring.aspect.exspandMethod;

import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.DeclareParents;

@Aspect
public class MobileAspect {
/**
* value指定了要为哪些类引入该接口
* <br/>
* com.xbz.learn.spring.aspect.exspandMethod.Mobile+表示所有的子类，不包括Mobile
* <br/>
*
*/
@DeclareParents(value="com.xbz.learn.spring.aspect.exspandMethod.Mobile+",
defaultImpl=SamplePad.class)
public static Pad pad;
}

JavaConfig类

注意：@EnableAspectJAutoProxy，不然一切都是浮云

package com.xbz.learn.spring.aspect.exspandMethod;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;

@Configuration
@EnableAspectJAutoProxy
public class JavaConfig {
@Bean
public MobileAspect mobileAspect(){
return new MobileAspect();
}
@Bean
public Mobile mobile(){
return new SampleMobile();
}

}

接下来，见证奇迹的时刻：手机变电脑

测试类

package com.xbz.learn.spring.aspect.exspandMethod;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes={JavaConfig.class})
public class JavaConfigTest {
@Autowired
private Mobile mobile;
@Test
public void testMobileAspect(){
System.out.println(mobile.getClass().getName());
System.out.println("This mobile is a pad?"+(mobile instanceof Pad));
Pad pad=(Pad) mobile;
pad.watchMovie();
}
}

XML 配置方案

<?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:p="http://www.springframework.org/schema/p"
xmlns:c="http://www.springframework.org/schema/c"

xmlns:context="http://www.springframework.org/schema/context"
xmlns:aop="
4000 http://www.springframework.org/schema/aop" xmlns:mvc="http://www.springframework.org/schema/mvc"

xsi:schemaLocation=
"http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd  http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
 http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
 http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
">
<!-- 使用CGLIB代理创建代理对象，默认使用JDK代理 -->
<aop:aspectj-autoproxy proxy-target-class="false"></aop:aspectj-autoproxy>
<aop:config>
<aop:aspect >
<aop:declare-parents
types-matching="com.xbz.learn.spring.aspect.exspandMethod.Mobile+"
implement-interface="com.xbz.learn.spring.aspect.exspandMethod.Pad"
default-impl="com.xbz.learn.spring.aspect.exspandMethod.SamplePad"
/>
</aop:aspect>
</aop:config>
<!-- 目标类 -->
<bean id="mobile" class="com.xbz.learn.spring.aspect.exspandMethod.SampleMobile"></bean>
</beans>