概述
一个连接点可以同时匹配多个切点，切点对应的增强在连接点上的织入顺序到底是如何安排呢？这个问题需要分三种情况讨论：
如果增强在同一个切面类中声明，则依照增强在切面类中定义的顺序进行织入；
如果增强位于不同的切面类中，且这些切面类都实现了org.springframework.core.Ordered接口，则由接口方法的顺序号决定（顺序号小的先织入）；
如果增强位于不同的切面类中，且这些切面类没有实现org.springframework.core.Ordered接口，织入的顺序是不确定的。
我们可以通过下图描述这种织入的规则：
切面类A和B都实现为Ordered接口，A切面类对应序号为1，B切面类对应序号为2，A切面类按顺序定义了3个增强，B切面类按顺序定义两个增强，这5个增强对应的切点都匹配某个目标类的连接点，则增强织入的顺序为图中虚线所示。
示例
代码已托管到Github—> https://github.com/yangshangwei/SpringMaster
业务类
package com.xgj.aop.spring.advisor.aspectJAdvance.pointOrder; import org.springframework.stereotype.Component; /** * * * @ClassName: Bussiness * * @Description: @Component标注的Bean * * @author: Mr.Yang * * @date: 2017年9月11日 上午1:38:06 */ @Component public class Bussiness { public void dealBussiness() { System.out.println("dealBussiness executed"); } }
切面1
package com.xgj.aop.spring.advisor.aspectJAdvance.pointOrder; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Before; import org.springframework.core.annotation.Order; /** * * * @ClassName: PointOrderOneAspect * * @Description: @Aspect标注的切面,实现Ordered接口 重写getOrder方法 后者 使用注解 @Order(value = 1) * * @author: Mr.Yang * * @date: 2017年9月11日 上午1:35:42 */ @Aspect @Order(value = 1) public class PointOrderOneAspect { @Before("execution(* dealBussiness(..))") public void method1() { System.out.println("method1 executed"); } @Before("execution(* dealBussiness(..))") public void method2() { System.out.println("method2 executed"); } @Before("execution(* dealBussiness(..))") public void method3() { System.out.println("method3 executed"); } }
切面2
package com.xgj.aop.spring.advisor.aspectJAdvance.pointOrder; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Before; import org.springframework.core.annotation.Order; /** * * * @ClassName: PointOrderTwoAspect * * @Description: @Aspect标注的切面,实现Ordered接口 重写getOrder方法 后者 使用注解 @Order(value = 2) * * @author: Mr.Yang * * @date: 2017年9月11日 上午1:36:02 */ @Aspect @Order(value = 2) public class PointOrderTwoAspect { @Before("execution(* dealBussiness(..))") public void method4() { System.out.println("method4 executed"); } @Before("execution(* dealBussiness(..))") public void method5() { System.out.println("method5 executed"); } }
配置文件
<?xml version="1.0" encoding="UTF-8"?> <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"> <!-- (1)声明Context命名空间以及Schema文件 (2)扫描类包以及应用注解定义的bean --> <context:component-scan base-package="com.xgj.aop.spring.advisor.aspectJAdvance.pointOrder"/> <!-- 基于@AspectJ切面的驱动器 --> <aop:aspectj-autoproxy proxy-target-class="true"/> <!-- 使用了@AspectJ注解的切面类 --> <bean class="com.xgj.aop.spring.advisor.aspectJAdvance.pointOrder.PointOrderOneAspect"/> <bean class="com.xgj.aop.spring.advisor.aspectJAdvance.pointOrder.PointOrderTwoAspect"/> </beans>
测试类
package com.xgj.aop.spring.advisor.aspectJAdvance.pointOrder; import org.junit.Test; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class PointOrderAspectTest { @Test public void test() { ApplicationContext ctx = new ClassPathXmlApplicationContext( "com/xgj/aop/spring/advisor/aspectJAdvance/pointOrder/conf-pointOrder.xml"); Bussiness bussiness = ctx.getBean("bussiness", Bussiness.class); bussiness.dealBussiness(); } }
运行结果
2017-09-11 01:46:32,790 INFO [main] (AbstractApplicationContext.java:583) - Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@3695de1a: startup date [Mon Sep 11 01:46:32 BOT 2017]; root of context hierarchy 2017-09-11 01:46:32,869 INFO [main] (XmlBeanDefinitionReader.java:317) - Loading XML bean definitions from class path resource [com/xgj/aop/spring/advisor/aspectJAdvance/pointOrder/conf-pointOrder.xml] method1 executed method2 executed method3 executed method4 executed method5 executed dealBussiness executed
