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循序渐进之Spring AOP(4) - Introduction

前面描述的几种增强(Advice)都是在目标方法范围内织入,而引介(Introduction)不同,直接在类级别上添加目标未实现的接口方法。

在Spring中可以通过扩展DelegatingIntroductionInterceptor类来实现引介增强类。

下面通过这种方式给一辆普通汽车加上无人驾驶功能

接口Auto

public interface Auto {
	void driving();
}
实现类

public class MyCar implements Auto {
	@Override
	public void driving() {
		System.out.println("开车了");
	}
}
新建一个接口Intelligent,它具有一个自动驾驶的方法,我们将把这个方法"添加"到MyCar上

public interface Intelligent {
	void selfDriving();
}
实现类IntelligentCar,注意,继承了DelegatingIntroductionInterceptor类

public class IntelligentCar extends DelegatingIntroductionInterceptor implements Intelligent {

	@Override
	public void selfDriving() {
		System.out.println("开启无人驾驶了, 别挡路");
	}

	public Object invoke(MethodInvocation invocation) throws Throwable {
		Object obj = super.invoke(invocation);
		return obj;
	}
}
applicationContext.xml

<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: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="carTarget" class="demo.aop.MyCar" />
	<bean id="introduceAdvisor" class="org.springframework.aop.support.DefaultIntroductionAdvisor">
		<constructor-arg>
			<bean class="demo.aop.IntelligentCar" />
		</constructor-arg>
	</bean>
	<bean id="myCar" class="org.springframework.aop.framework.ProxyFactoryBean"
		p:target-ref="carTarget"
		p:interceptorNames="introduceAdvisor"
		p:proxyTargetClass="true" />
</beans>
测试代码

	public static void main(String[] args) {
		ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");

		Auto car = (Auto)context.getBean("myCar");
		car.driving();
		Intelligent intelligentCar = (Intelligent)car;
		intelligentCar.selfDriving();
	}
运行结果

开车了
开启无人驾驶了, 别挡路








posted on 2016-04-11 21:09  autfish  阅读(164)  评论(0编辑  收藏  举报