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如何让注释作为为类级注释定义的 Advice 的参数传递？可能吗？

从这里的帖子中，我能够获得标识类中所有由特定注释标记的公共方法的切入点。我也能够得到应用的建议。但是，我不知道如何在上述情况下获取作为参数传递的注释变量。

对于方法级注释，我可以获得切入点和建议，在其中我可以将注释作为参数传递，但我不知道如何为类级注释实现相同的效果。

下面的代码有效，但我需要在下面的程序中获取注释作为建议“<strong>LogExecutionTimeByClass”的参数，但我无法获得相应的建议或切入点。

注解： 

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，不能选择使用 Spring。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。

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

任何指针都会有所帮助。

4

1 回答 1

20

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。您将可以轻松地将其调整为 @AspectJ 注释样式：

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

如你看到的，

  • 不需要around()建议，before()就足够了，除非您想操纵任何参数或阻止捕获的方法执行，
  • 如果您只使用正确的语法，则可以通过@annotation()或绑定到命名参数。@within()

享受！:-)

更新：为了您的方便，这是方面的@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问题：

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。

于 2013-07-08T15:32:48.277 回答