Spring @Aspect进行类的接口扩展：
XML：
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.springframework.org/schema/beans" xmlns:p="http://www.springframework.org/schema/p"
xmlns:util="http://www.springframework.org/schema/util" xmlns:context="http://www.springframework.org/schema/context" xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.1.xsd
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.1.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.1.xsd">
<!-- 这个声明会创建AnnotationAwareAspectJAutoProxyCreator，进行切面Bean的代理 -->
<aop:aspectj-autoproxy />
<!-- 必须将切面类声明为一个Bean -->
<bean id="introduceAspect" class="com.stono.sprtest3.IntroduceAspect"></bean>
<bean id="singer" class="com.stono.sprtest3.Singer"></bean>
</beans>
AppBean:
package com.stono.sprtest3;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class AppBeans13 {
public static void main(String[] args) {
@SuppressWarnings("resource")
ApplicationContext context = new ClassPathXmlApplicationContext("appbeans13.xml");
// 有接口必须使用接口，使用Singer类会出现ClassCastException；
Performer bean = (Performer) context.getBean("singer");
IntroduceI introduceI = (IntroduceI) bean;
introduceI.introduce();
}
}
Aspect:
package com.stono.sprtest3;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.DeclareParents;
@Aspect
public class IntroduceAspect {
// 为Performer接口扩展增加IntroduceI接口；
@DeclareParents(value = "com.stono.sprtest3.Performer+", defaultImpl = DefaultIntro.class)
public static IntroduceI introduceI;
}
POJO:
package com.stono.sprtest3;
public interface Performer {
void perform();
}
package com.stono.sprtest3;
public class Singer implements Performer {
public void perform() {
System.out.println("com.stono.sprtest3.Singer.perform()");
}
}
package com.stono.sprtest3;
public interface IntroduceI {
void introduce();
} package com.stono.sprtest3;
public class DefaultIntro implements IntroduceI {
@Override
public void introduce() {
System.out.println("this is default introduce");
}
}