@AspectJ 类级别的注解建议，以注解作为方法参数 [英] @AspectJ Class level Annotation Advice with Annotation as method argument

问题描述

如何让注释作为为 Advice 定义的参数传递类级注释?可能吗?

How can I get the annotation to be passed as the argument for the Advice defined for class-level annotation? Is it possible?

来自帖子这里 我能够获得标识类中所有公共方法的切入点，这些方法由特定的注释标记.我也能够得到应用的建议.但是，我不知道如何获取在上述情况下作为参数传递的注释变量.

From the post here I am able to get the point cut that identifies all the public method in the class which is marked by a specific Annotation. I am able to get the advice applied as well. However, I don’t know how to get the annotation variable passed as argument in above case.

对于方法级注解，我可以获得切入点和建议，我可以在其中获取作为参数传递的注解，但我不知道如何为类级注解实现相同的目标.

For a method-level annotation, I am able to get the pointcut and advice in which I can get the annotation passed as argument, but I don’t know how to achieve the same for class-level annotation.

下面的代码有效，但我需要在下面的程序中获得注释作为建议LogExecutionTimeByClass"的参数，我无法获得适当的建议或切入点.

The below code works, but I need to get the annotation as the argument for the advice "LogExecutionTimeByClass" in below program and I couldn’t able to get appropriate advice or pointcut for the same.

注释:

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface LogExecutionTime {
String level();
}

方面:

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;

@Aspect
public class LogTimeAspect {

    /*
     * Pointcut to match all the public methods.
    */
    @Pointcut("execution(public * *(..))")
    public void publicMethod() {}

    /*
     * Advice for the public methods that are marked with Annotation "LogExecutionTime" and it works as expected no issue.
    */ 
    @Around("publicMethod() && @annotation(annotation) ")
    public Object LogExecutionTimeByMethod(final ProceedingJoinPoint joinPoint,final LogExecutionTime annotation) throws Throwable 
    {
        System.out.println("Invoking the method " +joinPoint.getSignature() +" by LogExecutionTimeByMethod Advice");
        return joinPoint.proceed();
    }


    /*
     * Pointcut to match all the public methods that are defined under the Class marked with Annotation LogExecutionTime.
    */
    @Pointcut("within(@LogExecutionTime *)")
    public void beanAnnotatedWithMonitor() {}

    @Pointcut("publicMethod() && beanAnnotatedWithMonitor()")
    public void publicMethodInsideAClassMarkedWithAtMonitor() {}

    /*
     * Below Advice works but I need the LogExecutionTime annotation as an argument to below method. (similar to the advice "LogExecutionTimeByMethod" 
     * defined above)
    */
    @Around("publicMethodInsideAClassMarkedWithAtMonitor()")
    public Object LogExecutionTimeByClass(final ProceedingJoinPoint joinPoint) throws Throwable 
    {
        System.out.println("Invoking the method " +joinPoint.getSignature() +" by  LogExecutionTimeByClass Advice");
        //System.out.println("Invoked by " + annotation.value()); //Need the Annotation Variable here as well...
        return joinPoint.proceed();
    }

/*
    */
}

注释类:

@LogExecutionTime(level="Class_Level_Invocation")
public class Operator {

    @LogExecutionTime(level="Method_Level_Invocation")
    public void operate()  throws InterruptedException {
        Thread.sleep(1000);
    }

    public void operate1() throws InterruptedException {
        Thread.sleep(1000);
    }
}

主程序:

public class AspectJMain {
     public static void main(String[] args) throws InterruptedException {
            Operator op = new Operator();
            op.operate();
            op.operate1();
        }
}

输出:

Invoking the method void Operator.operate() by LogExecutionTimeByMethod Advice
Invoking the method void Operator.operate() by  LogExecutionTimeByClass Advice
Invoking the method void Operator.operate1() by  LogExecutionTimeByClass Advice

请注意，使用 Spring 不是一种选择.我必须使用 AspectJ 编译器.我编译了我的类并将它们打包为 jar 并使用 ApsectJ 编译器使用以下命令编织方面.

Please note that using Spring is is not an option. I have to use AspectJ compiler. I compiled my classes and packaged them as jar and use ApsectJ compiler to woven the aspect using below command.

ajc -inpath core.jar -outjar ..\lib\core_woven.jar -1.5

ajc -inpath core.jar -outjar ..\lib\core_woven.jar -1.5

任何指针都会有所帮助.

Any pointer would be helpful.

推荐答案

解决方案其实很简单.我正在以原生 AspectJ 风格编写代码，为了清晰起见，我更喜欢它.您可以轻松地将其调整为@AspectJ 注释样式:

The solution is actually quite simple. I am writing my code in native AspectJ style, I prefer it for clarity. You will be easily able to adjust it to @AspectJ annotation style:

public aspect LogTimeAspect {
    pointcut publicMethod() : execution(public * *(..));

    before(LogExecutionTime logAnn) : publicMethod() && @annotation(logAnn) {
        System.out.println(thisJoinPointStaticPart + " -> " + logAnn.level());
    }

    before(LogExecutionTime logAnn) : publicMethod() && @within(logAnn) {
        System.out.println(thisJoinPointStaticPart + " -> " + logAnn.level());
    }
}

输出如下:

execution(void Operator.operate()) -> Method_Level_Invocation
execution(void Operator.operate()) -> Class_Level_Invocation
execution(void Operator.operate1()) -> Class_Level_Invocation

如你所见，

• 不需要 around() 建议，before() 就足够了，除非您想操作任何参数或阻止捕获的方法执行，
• 如果您使用正确的语法，您可以通过 @annotation() 或 @within() 将有问题的注释绑定到命名参数.

• there is no need for around() advice, before() is sufficient unless you want to manipulate any parameters or block the captured method executions,
• you can bind the annotations in question via @annotation() or @within() to named parameters if you just use the correct syntax.

享受吧！:-)

更新:为了您的方便，这里是方面的@AspectJ 版本，因为您似乎在从本机语法调整我的解决方案时遇到了问题:

Update: Here is the @AspectJ version of the aspect for your convenience and because you seemed to have problems adapting my solution from the native syntax:

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;

@Aspect
public class LogTimeAspect {
    @Pointcut("execution(public * *(..))")
    public void publicMethod() {}

    @Around("publicMethod() && @annotation(logAnn)")
    public Object LogExecutionTimeByMethod(ProceedingJoinPoint joinPoint, LogExecutionTime logAnn) throws Throwable {
        System.out.println(joinPoint + " -> " + logAnn.level());
        return joinPoint.proceed();
    }

    @Around("publicMethod() && @within(logAnn)")
    public Object LogExecutionTimeByClass(ProceedingJoinPoint joinPoint, LogExecutionTime logAnn) throws Throwable {
        System.out.println(joinPoint + " -> " + logAnn.level());
        return joinPoint.proceed();
    }
}

结果将与我的原始版本相同.

The results will be identical to my original version.

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