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
本文标题：Spring-AOP @AspectJ切点函数之@within()和@target
本文链接：https://blog.quwenai.cn/post/6711.html
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