概述
除了@annotation和@args外，还有另外两个用于注解的切点函数，分别是@target和@within.
和@annotation @args函数一样，@target和@within也只接受注解类名作为入参。
其中@target(M)匹配任意标注了@M的目标类，而@within(M)匹配标注了@M的类及其子孙类（子类经测试匹配不到，欢迎指正）
@target(M)的匹配规则
@target使用@target(注解类型全限定名)匹配当前目标对象类型的执行方法, 必须是在目标对象上声明注解，在接口上声明不起作用
@within(M)的匹配规则
经验证，目前发现和 @target(M)的匹配规则是一样的。
@within(注解类型全限定名)匹配所有持有指定注解的类里面的方法, 即要把注解加在类上. 在接口上声明不起作用 。 子孙类经测试匹配不到，如有错误烦请指出。
实例
代码已托管到Github—> https://github.com/yangshangwei/SpringMaster
@target
首先自定义一个注解用于测试用
package com.xgj.aop.spring.advisor.aspectJ.function.attarget; import java.lang.annotation.Documented; import java.lang.annotation.ElementType; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; /** * * * @ClassName: Mark * * @Description: 自定义注解 * * @author: Mr.Yang * * @date: 2017年9月5日 下午12:02:46 */ @Retention(RetentionPolicy.RUNTIME) @Target(ElementType.TYPE) @Documented public @interface Mark { public String value() default ""; }
4个注解标注的POJO ，继承关系 C3 -->C2–> C1–> C0
package com.xgj.aop.spring.advisor.aspectJ.function.attarget; import org.springframework.stereotype.Component; /** * * * @ClassName: C0 * * @Description: @Component 标注的Bean * * @author: Mr.Yang * * @date: 2017年9月5日 下午1:36:37 */ @Component public class C0 { public void methodName() { System.out.println("C0 method executed"); } }
C1类声明处标注了自定义注解@Mark
package com.xgj.aop.spring.advisor.aspectJ.function.attarget; import org.springframework.stereotype.Component; @Mark @Component public class C1 extends C0 { public void methodName() { System.out.println("C1 method executed"); } }
C2类声明处标注了自定义注解@Mark
package com.xgj.aop.spring.advisor.aspectJ.function.attarget; import org.springframework.stereotype.Component; @Mark @Component public class C2 extends C1 { public void methodName() { System.out.println("C2 method executed"); } }
package com.xgj.aop.spring.advisor.aspectJ.function.attarget; import org.springframework.stereotype.Component; @Component public class C3 extends C2 { public void methodName() { System.out.println("C3 method executed"); } }
使用@Aspect标注的环绕增强切面
package com.xgj.aop.spring.advisor.aspectJ.function.attarget; import org.aspectj.lang.ProceedingJoinPoint; import org.aspectj.lang.annotation.Around; import org.aspectj.lang.annotation.Aspect; /** * * * @ClassName: AtTargetAspect * * @Description: 标注了@Aspect的切面 环绕增强切面 * * @author: Mr.Yang * * @date: 2017年9月5日 上午11:59:26 */ @Aspect public class AtTargetAspect { @Around("@target(com.xgj.aop.spring.advisor.aspectJ.function.attarget.Mark)") public void crossCuttingCode(ProceedingJoinPoint joinPoint) throws Throwable { System.out.println("****AtTargetAspect.crossCuttingCode() : " + joinPoint.getSignature().getName() + ": Before Method Execution"); try { joinPoint.proceed(); } finally { // Do Something useful, If you have } System.out.println("****AtTargetAspect.crossCuttingCode() : " + joinPoint.getSignature().getName() + ": After Method Execution"); } }
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.aspectJ.function.attarget"/> <!-- 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.aspectJ.function.attarget.AtTargetAspect"/> </beans>
测试代码
package com.xgj.aop.spring.advisor.aspectJ.function.attarget; import org.junit.Test; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class AtTargetAspectTest { private ApplicationContext ctx; @Test public void test() { ctx = new ClassPathXmlApplicationContext( "classpath:com/xgj/aop/spring/advisor/aspectJ/function/attarget/conf-attarget.xml"); C0 c0 = ctx.getBean("c0", C0.class); C1 c1 = ctx.getBean("c1", C1.class); C2 c2 = ctx.getBean("c2", C2.class); C3 c3 = ctx.getBean("c3", C3.class); // C0没有标注了@Mark，不会被织入增强 c0.methodName(); // C1标注了@Mark，会被织入增强 c1.methodName(); // C2标注了@Mark，会被织入增强 c2.methodName(); // C3没有标注了@Mark，不会被织入增强 c3.methodName(); } }
运行结果：
2017-09-05 13:40:56,244 INFO [main] (AbstractApplicationContext.java:583) - Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@c24cb3: startup date [Tue Sep 05 13:40:56 BOT 2017]; root of context hierarchy 2017-09-05 13:40:56,338 INFO [main] (XmlBeanDefinitionReader.java:317) - Loading XML bean definitions from class path resource [com/xgj/aop/spring/advisor/aspectJ/function/attarget/conf-attarget.xml] C0 method executed ****AtTargetAspect.crossCuttingCode() : methodName: Before Method Execution C1 method executed ****AtTargetAspect.crossCuttingCode() : methodName: After Method Execution ****AtTargetAspect.crossCuttingCode() : methodName: Before Method Execution C2 method executed ****AtTargetAspect.crossCuttingCode() : methodName: After Method Execution C3 method executed
C1 和 C2标注了@Mark注解，可以看到成功的织入了@Around环绕增强
@within
自定义一个注解
package com.xgj.aop.spring.advisor.aspectJ.function.atwithin; import java.lang.annotation.Documented; import java.lang.annotation.ElementType; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; /** * * * @ClassName: Mark * * @Description: 自定义注解 * * @author: Mr.Yang * * @date: 2017年9月5日 下午12:02:46 */ @Retention(RetentionPolicy.RUNTIME) @Target(ElementType.TYPE) @Documented public @interface Mark2 { public String value() default ""; }
4个注解声明的POJO Bean
package com.xgj.aop.spring.advisor.aspectJ.function.atwithin; import org.springframework.stereotype.Component; /** * * * @ClassName: C0 * * @Description: @Component 标注的Bean * * @author: Mr.Yang * * @date: 2017年9月5日 下午1:36:37 */ @Component public class A0 { public void methodName() { System.out.println("A0 method executed \n"); } }
package com.xgj.aop.spring.advisor.aspectJ.function.atwithin; import org.springframework.stereotype.Component; /** * * * @ClassName: A1 * * @Description: 标注了@Mark2，可以被增强 * * @author: Mr.Yang * * @date: 2017年9月5日 下午6:02:21 */ @Mark2 @Component public class A1 extends A0 { public void methodName() { System.out.println("A1 method executed"); } }
package com.xgj.aop.spring.advisor.aspectJ.function.atwithin; import org.springframework.stereotype.Component; @Component public class A2 extends A1 { public void methodName() { System.out.println("A2 method executed"); } }
package com.xgj.aop.spring.advisor.aspectJ.function.atwithin; import org.springframework.stereotype.Component; @Component public class A3 extends A2 { public void methodName() { System.out.println("A3 method executed"); } }
切面 实现了Ordered接口
package com.xgj.aop.spring.advisor.aspectJ.function.atwithin; import org.aspectj.lang.ProceedingJoinPoint; import org.aspectj.lang.annotation.Around; import org.aspectj.lang.annotation.Aspect; import org.springframework.core.Ordered; /** * * * @ClassName: AtWithinAspect * * @Description: 标注了@Aspect 环绕增强切面 * * @author: Mr.Yang * * @date: 2017年9月5日 下午1:53:40 */ @Aspect public class AtWithinAspect implements Ordered { @Around("@within(com.xgj.aop.spring.advisor.aspectJ.function.atwithin.Mark2)") public void crossCuttingCode(ProceedingJoinPoint joinPoint) throws Throwable { System.out.println("****AtWithinAspect.crossCuttingCode() : " + joinPoint.getSignature().getName() + ": Before Method Execution"); try { joinPoint.proceed(); } finally { // Do Something useful, If you have } System.out.println("****AtWithinAspect.crossCuttingCode() : " + joinPoint.getSignature().getName() + ": After Method Execution \n"); } @Override public int getOrder() { return 1; } }
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.aspectJ.function.atwithin"/> <!-- 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.aspectJ.function.atwithin.AtWithinAspect"/> </beans>
测试类
package com.xgj.aop.spring.advisor.aspectJ.function.atwithin; import org.junit.Test; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class AtWithinAspectTest { private ApplicationContext ctx; @Test public void test() { ctx = new ClassPathXmlApplicationContext( "classpath:com/xgj/aop/spring/advisor/aspectJ/function/atwithin/conf-atwithin.xml"); A0 a0 = ctx.getBean("a0", A0.class); A1 a1 = ctx.getBean("a1", A1.class); A2 a2 = ctx.getBean("a2", A2.class); A3 a3 = ctx.getBean("a3", A3.class); // A0没有标注@Mark，不会被织入增强 a0.methodName(); // A1标注了@Mark，会被织入增强 a1.methodName(); // A2没有标注@Mark，不会被织入增强 a2.methodName(); // A3没有标注@Mark，不会被织入增强 a3.methodName(); } }
运行结果：
2017-09-05 18:04:01,685 INFO [main] (AbstractApplicationContext.java:583) - Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@c24cb3: startup date [Tue Sep 05 18:04:01 BOT 2017]; root of context hierarchy 2017-09-05 18:04:01,793 INFO [main] (XmlBeanDefinitionReader.java:317) - Loading XML bean definitions from class path resource [com/xgj/aop/spring/advisor/aspectJ/function/atwithin/conf-atwithin.xml] A0 method executed ****AtWithinAspect.crossCuttingCode() : methodName: Before Method Execution A1 method executed ****AtWithinAspect.crossCuttingCode() : methodName: After Method Execution A2 method executed A3 method executed
注意事项
如果标注了@M注解的是一个接口，则所有实现该接口的类并不匹配@within(M) . 假设接口Waiter标注了@Mark注解，但是它的实现类NaiveWaiter、NaughtyWaiter这些接口实现类灭有标注@Mark, 则@within(com.xgj.Mark) 和 @target(com,xgj.Mark)都不匹配NaiveWaiter、NaughtyWaiter。 因为@within() @target() @annotation函数都是针对目标类而言的，而非针对运行时的引用类型而言。 需要特别注意。
验证过程见github中的 com.xgj.aop.spring.advisor.aspectJ.function.atwithin2
输出结果：
2017-09-05 18:11:18,171 INFO [main] (AbstractApplicationContext.java:583) - Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@24b9371e: startup date [Tue Sep 05 18:11:18 BOT 2017]; root of context hierarchy 2017-09-05 18:11:18,285 INFO [main] (XmlBeanDefinitionReader.java:317) - Loading XML bean definitions from class path resource [com/xgj/aop/spring/advisor/aspectJ/function/atwithin2/beans.xml] NaughtyWaiter:greet to XiaoGong... NaiveWaiter:greet to Jiang...
标注在接口上的@@Monitorable，使用within ，实现类中的方法并没有匹配
