@annotation()概述
@annotation表示標(biāo)注了某個注解的所有方法轴合。
下面通過一個實例說明@annotation()的用法总滩。 AnnotationTestAspect定義了一個后置切面增強，該增強將應(yīng)用到標(biāo)注了NeedTest的目標(biāo)方法中蒜危。
實例
代碼已托管到Github—> https://github.com/yangshangwei/SpringMaster
首先我們先自定義一個注解@NeedTest硝训。
如何自定義注解請參考Java-Java5.0注解解讀
package com.xgj.aop.spring.advisor.aspectJ.function;
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: NeedTest
*
* @Description: 自定義注解@NeedTest
*
* @author: Mr.Yang
*
* @date: 2017年8月26日 下午11:19:12
*/
// 聲明注解的保留期限
@Retention(RetentionPolicy.RUNTIME)
// 聲明可以使用該注解的目標(biāo)類型
@Target(ElementType.METHOD)
@Documented
public @interface NeedTest {
// 聲明注解成員
boolean value() default false;
}
下面我們定義接口 Waiter
package com.xgj.aop.spring.advisor.aspectJ.function;
public interface Waiter {
public void greetTo(String clientName);
public void serverTo(String clientName);
}
接口實現(xiàn)類 兩個NaiveWaiter 和 NaughtWaiter
package com.xgj.aop.spring.advisor.aspectJ.function;
public class NaiveWaiter implements Waiter {
@NeedTest(true)
@Override
public void greetTo(String clientName) {
System.out.println("NaiveWaiter:greet to " + clientName);
}
@Override
public void serverTo(String clientName) {
System.out.println("NaiveWaiter:server to " + clientName);
}
public void smile(String clientName, int times) {
System.out.println("NaiveWaiter:smile to " + clientName + " " + times
+ " times");
}
}
package com.xgj.aop.spring.advisor.aspectJ.function;
public class NaughtWaiter implements Waiter {
@Override
public void greetTo(String clientName) {
System.out.println("NaughtWaiter:greet to " + clientName);
}
@NeedTest(true)
@Override
public void serverTo(String clientName) {
System.out.println("NaughtWaiter:server to " + clientName);
}
public void joke(String clientName, int times) {
System.out.println("NaughtyWaiter:play " + times + " jokes to "
+ clientName);
}
}
我們可以看到 NaiveWaiter#greetTo()方法標(biāo)注了@NeedTest响委， NaughtWaiter#serverTo()也標(biāo)注了@NeedTest，我們的目標(biāo)就是將后置增強織入到這兩個標(biāo)注了@NeedTest的方法中窖梁。
接下來編寫切面的橫切邏輯
package com.xgj.aop.spring.advisor.aspectJ.function.annotationFun;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.Aspect;
/**
*
*
* @ClassName: AnnotationTestAspect
*
* @Description: 切面 赘风、 后置增強 ,@annotation表示標(biāo)注了某個注解的所有方法
*
* @author: Mr.Yang
*
* @date: 2017年8月26日 下午11:23:53
*/
@Aspect
public class AnnotationTestAspect {
@AfterReturning("@annotation(com.xgj.aop.spring.advisor.aspectJ.function.NeedTest)")
public void needTest() {
System.out.println("needTest() executed,some logic is here");
}
}
接下來通過Spring自動應(yīng)用切面，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"
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">
<!-- 使用基于Schema的aop命名空間進行配置 -->
<!-- 基于@AspectJ切面的驅(qū)動器 -->
<aop:aspectj-autoproxy/>
<!-- 目標(biāo)Bean -->
<bean id="naiveWaiter" class="com.xgj.aop.spring.advisor.aspectJ.function.NaiveWaiter"/>
<bean id="naughtWaiter" class="com.xgj.aop.spring.advisor.aspectJ.function.NaughtWaiter"/>
<!-- 使用了@AspectJ注解的切面類 -->
<bean class="com.xgj.aop.spring.advisor.aspectJ.function.annotationFun.AnnotationTestAspect"/>
</beans>
最后編寫測試代碼：
package com.xgj.aop.spring.advisor.aspectJ.function.annotationFun;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.xgj.aop.spring.advisor.aspectJ.function.Waiter;
public class AnnotationTestAspcetTest {
@Test
public void test() {
ApplicationContext ctx = new ClassPathXmlApplicationContext(
"com/xgj/aop/spring/advisor/aspectJ/function/annotationFun/conf-annotation.xml");
// 必須是接口類型,否則拋類型轉(zhuǎn)換異常
Waiter waiter = (Waiter) ctx.getBean("naiveWaiter");
// 因為greetTo標(biāo)注了@NeedTest,因此會被后置增強
waiter.greetTo("XiaoGongJiang");
waiter.serverTo("XiaoGongJiang");
Waiter naughtWaiter = (Waiter) ctx.getBean("naughtWaiter");
// serverTo標(biāo)注了@NeedTest,因此會被后置增強
naughtWaiter.serverTo("XiaoGongJiang");
}
}
運行結(jié)果：
2017-08-27 01:24:22,551 INFO [main] (AbstractApplicationContext.java:583) - Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@6ac604: startup date [Sun Aug 27 01:24:22 BOT 2017]; root of context hierarchy
2017-08-27 01:24:22,647 INFO [main] (XmlBeanDefinitionReader.java:317) - Loading XML bean definitions from class path resource [com/xgj/aop/spring/advisor/aspectJ/function/annotationFun/conf-annotation.xml]
NaiveWaiter:greet to XiaoGongJiang
needTest() executed,some logic is here
NaiveWaiter:server to XiaoGongJiang
NaughtWaiter:server to XiaoGongJiang
needTest() executed,some logic is here
從輸出結(jié)果中可以看出纵刘，切面被正確的織入到了標(biāo)注有@NeedTest注解的方法中邀窃。
