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Spring-AOP @AspectJ切点函数之@annotation()用法

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@annotation()概述

@annotation表示标注了某个注解的所有方法.

下面通过一个实例说明@annotation()的用法。 AnnotationTestAspect定义了一个后置切面增强,该增强将应用到标注了NeedTest的目标方法中.

实例

代码已托管到Github—> https://github.com/yangshangwei/SpringMaster 。

Spring-AOP @AspectJ切点函数之@annotation()用法

首先我们先自定义一个注解@NeedTest.

如何自定义注解请参考Java-Java5.0注解解读 。

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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: 自定义注解@NeedTest
  *
  * @author: Mr.Yang
  *
  * @date: 2017年8月26日 下午11:19:12
  */
// 声明注解的保留期限
@Retention (RetentionPolicy.RUNTIME)
// 声明可以使用该注解的目标类型
@Target (ElementType.METHOD)
@Documented
public @interface NeedTest {
     // 声明注解成员
     boolean value() default false ;
}

下面我们定义接口 Waiter 。

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package com.xgj.aop.spring.advisor.aspectJ.function;
public interface Waiter {
  public void greetTo(String clientName);
  public void serverTo(String clientName);
}

接口实现类 两个NaiveWaiter 和 NaughtWaiter 。

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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" );
     }
}
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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);
     }
}

我们可以看到 NaiveWaiter#greetTo()方法标注了@NeedTest, NaughtWaiter#serverTo()也标注了@NeedTest,我们的目标就是将后置增强织入到这两个标注了@NeedTest的方法中.

接下来编写切面的横切逻辑 。

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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 、 后置增强 ,@annotation表示标注了某个注解的所有方法
  *
  * @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" );
     }
}

接下来通过Spring自动应用切面,配置文件如下 。

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<? 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命名空间进行配置 -->
 
<!-- 基于@AspectJ切面的驱动器 -->
< aop:aspectj-autoproxy />
 
<!-- 目标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注解的切面类 -->
< bean class = "com.xgj.aop.spring.advisor.aspectJ.function.annotationFun.AnnotationTestAspect" />
</ beans >

最后编写测试代码:

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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" );
   // 必须是接口类型,否则抛类型转换异常
   Waiter waiter = (Waiter) ctx.getBean( "naiveWaiter" );
   // 因为greetTo标注了@NeedTest,因此会被后置增强
   waiter.greetTo( "XiaoGongJiang" );
   waiter.serverTo( "XiaoGongJiang" );
   Waiter naughtWaiter = (Waiter) ctx.getBean( "naughtWaiter" );
   // serverTo标注了@NeedTest,因此会被后置增强
   naughtWaiter.serverTo( "XiaoGongJiang" );
  }
}

运行结果:

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 。

从输出结果中可以看出,切面被正确的织入到了标注有@NeedTest注解的方法中.

以上为个人经验,希望能给大家一个参考,也希望大家多多支持我.

原文链接:https://artisan.blog.csdn.net/article/details/77619875 。

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