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：
<?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.namePoint"/> <!-- 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.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。
