Spring-AOP @AspectJ进阶之命名切点

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发布于 2021-08-17 10:01:49

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概述

在前面所举的例子中，比如

@Before("within(com.xgj.aop.spring.advisor.aspectJAdvance.pointcutComplex.*)"
			+ " && execution(* greetTo(..))")
	public void matchGreetTo() {
		System.out.println("matchGreetTo executed,some logic is here ");
	}

切点直接声明在增强方法处，这种切点声明方式称为匿名切点，匿名切点只能在声明处使用。

如果希望在其它地方重用一个切点，我们可以通过@Pointcut注解以及切面类方法对切点进行命名

示例

代码已托管到Github—> https://github.com/yangshangwei/SpringMaster

package com.xgj.aop.spring.advisor.aspectJAdvance.namePoint;

import org.aspectj.lang.annotation.Pointcut;

/**
 * 
 * 
 * @ClassName: NamePoint
 * 
 * @Description: 如果希望在其它地方重用一个切点，我们可以通过@Pointcut注解以及切面类方法对切点进行命名
 * 
 * @author: Mr.Yang
 * 
 * @date: 2017年9月10日 下午11:13:45
 */
public class NamePoint{

	/**
	 * 
	 * 
	 * @Title: inPackage
	 * 
	 * @Description: 通过注解方法inPackage()对该切点进行命名，方法可视域
	 *               修饰符为private,表明该命名切点只能在本切面类中使用。
	 * 
	 * 
	 * @return: void
	 */
	@Pointcut("within(com.xgj.aop.spring.advisor.aspectJAdvance.namePoint)")
	private void inPackage() {

	};

	/**
	 * 
	 * 
	 * @Title: greetTo
	 * 
	 * @Description: 通过注解方法greetTo()对该切点进行命名，方法可视域
	 *               修饰符为protected,表明该命名切点可以在当前包中的切面 类、子切面类中中使用。
	 * 
	 * 
	 * @return: void
	 */
	@Pointcut("execution(* greetTo(..))")
	protected void greetTo() {

	}

	/**
	 * 
	 * 
	 * @Title: inPkgGreetTo
	 * 
	 * @Description: 引用命名切点定义的切点，本切点也是命名切点， 它对应的可视域为public
	 * 
	 * 
	 * @return: void
	 */
	@Pointcut("inPackage() and greetTo()")
	public void inPkgGreetTo() {

	}

}

上面上述示例中定义了3个命名切点，命名切点的使用类方法作为切点的名称，此外方法的访问修饰符还控制了切点的可引用性，这种可引用性和类方法的可访问性相同，如private的切点只能在本类中引用，public的切点可以在任何类中引用。

命名切点仅利用方法名及访问修饰符的信息，所以习惯上，方法的返回类型为void，并且方法体为空。

我们可以通过下图更直观地了解命名切点的结构：

inPkgGreetTo()的切点引用了同类中的greetTo()切点，而inPkgGreetTo()切点可以被任何类引用。

你还可以扩展NamePoint类，通过类的继承关系定义更多的切点。命名切点定义好后，就可以在定义切面时通过名称引用切点.

来看个示例

假设有两个业务类

package com.xgj.aop.spring.advisor.aspectJAdvance.namePoint;

import org.springframework.stereotype.Component;

/**
 * 
 * 
 * @ClassName: NaiveWaiter
 * 
 * @Description: @Component注解标注的bean
 * 
 * @author: Mr.Yang
 * 
 * @date: 2017年9月10日 下午11:55:00
 */

@Component
public class NaiveWaiter {

	public void greetTo(String clientName) {
		System.out.println("NaiveWaiter greetTo " + clientName);
	}

	public void serverTo(String clientName) {
		System.out.println("NaiveWaiter serverTo " + clientName);
	}
}

package com.xgj.aop.spring.advisor.aspectJAdvance.namePoint;

import org.springframework.stereotype.Component;

@Component
public class CuteWaiter {
	public void greetTo(String clientName) {
		System.out.println("CuteWaiter greetTo " + clientName);
	}

	public void serverTo(String clientName) {
		System.out.println("CuteWaiter serverTo " + clientName);
	}
}

切点命名复用上面那个切点，然后编写切面NamePointAspect

package com.xgj.aop.spring.advisor.aspectJAdvance.namePoint;

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

/**
 * 
 * 
 * @ClassName: NamePointTest
 * 
 * @Description: 使用@Aspect注解标注的切面，演示命名切点的使用
 * 
 * @author: Mr.Yang
 * 
 * @date: 2017年9月10日 下午11:42:39
 */

@Aspect
public class NamePointAspect {
	/**
	 * 
	 * 
	 * @Title: pkgGreetTo
	 * 
	 * @Description: 引用了NamePoint.inPkgGreetTo()切点
	 * 
	 * 
	 * @return: void
	 */
	@AfterReturning("NamePoint.inPkgGreetTo()")
	public void pkgGreetTo() {
		System.out.println("pkgGreetTo exectued ,some logic is here ");
	}

	/**
	 * 
	 * 
	 * @Title: pkgGreetToNotNaiveWaiter
	 * 
	 * @Description: 在复合运算中使用了命名切点
	 * 
	 * 
	 * @return: void
	 */
	@AfterReturning("!target(com.xgj.aop.spring.advisor.aspectJAdvance.namePoint.NaiveWaiter) && NamePoint.inPkgGreetTo()")
	public void pkgGreetToNotNaiveWaiter() {
		System.out
				.println("pkgGreetToNotNaiveWaiter() executed,some logic is here");
	}
}

配置文件如下：

<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:aop="http://www.springframework.org/schema/aop"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="http://www.springframework.org/schema/beans 
		http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/aop
		http://www.springframework.org/schema/aop/spring-aop.xsd
		http://www.springframework.org/schema/context 
       	http://www.springframework.org/schema/context/spring-context.xsd">


<context:component-scan base-package="com.xgj.aop.spring.advisor.aspectJAdvance.namePoint"/>


<aop:aspectj-autoproxy proxy-target-class="true"/>
 

<bean class="com.xgj.aop.spring.advisor.aspectJAdvance.namePoint.NamePointAspect"/>

beans>

测试类

package com.xgj.aop.spring.advisor.aspectJAdvance.namePoint;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * 
 * 
 * @ClassName: NamePointAspectTest
 * 
 * @Description: 命名切点测试类
 * 
 * @author: Mr.Yang
 * 
 * @date: 2017年9月10日 下午11:56:50
 */

public class NamePointAspectTest {

	public static void main(String[] args) {
		ApplicationContext ctx = new ClassPathXmlApplicationContext(
				"classpath:com/xgj/aop/spring/advisor/aspectJAdvance/namePoint/conf-namePoint.xml");

		CuteWaiter cuteWaiter = ctx.getBean("cuteWaiter", CuteWaiter.class);
		NaiveWaiter naiveWaiter = ctx.getBean("naiveWaiter", NaiveWaiter.class);

		naiveWaiter.greetTo("XiaoGongJiang");
		System.out.println("================");

		cuteWaiter.greetTo("XiaoGongJiang");
		System.out.println("================");

		naiveWaiter.serverTo("XiaoGongJiang");
		System.out.println("================");

		cuteWaiter.serverTo("XiaoGongJiang");
	}
}

运行结果

2017-09-11 00:58:34,752  INFO [main] (AbstractApplicationContext.java:583) - Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@4888884e: startup date [Mon Sep 11 00:58:34 BOT 2017]; root of context hierarchy
2017-09-11 00:58:34,821  INFO [main] (XmlBeanDefinitionReader.java:317) - Loading XML bean definitions from class path resource [com/xgj/aop/spring/advisor/aspectJAdvance/namePoint/conf-namePoint.xml]
NaiveWaiter greetTo XiaoGongJiang
pkgGreetTo exectued ,some logic is here 
================
CuteWaiter greetTo XiaoGongJiang
pkgGreetTo exectued ,some logic is here 
pkgGreetToNotNaiveWaiter() executed,some logic is here
================
NaiveWaiter serverTo XiaoGongJiang
pkgGreetTo exectued ,some logic is here 
================
CuteWaiter serverTo XiaoGongJiang
pkgGreetTo exectued ,some logic is here 
pkgGreetToNotNaiveWaiter() executed,some logic is here

可以看到NaiveWaiter greetTo 方法没有织入第二个增强。

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原始发表：2017/09/11 ，如有侵权请联系 cloudcommunity@tencent.com 删除

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