在通知前后传递对象? [英] Pass object between before and after advice?

问题描述

是否可以在 before 通知中创建一个对象并将其传递给 after 通知?例如，如果我有方面:

Is it possible to create an object in a before advice and pass it to an after advice? For instance, if I have the aspect:

public aspect LoggingAspect {

    pointcut allMethods() : execution(* com.foo.Bar.*(..));

    before() : allMethods() {
        SomeObject foo = makeSomeObject();
    }

    after() : allMethods() {
      // access foo?
    }
}

我不能直接引用 foo 因为它不在范围内(触发编译器错误).是否有一些上下文可用于我可以将 foo 存储在其中的两个建议?

I can't directly reference foo since it's not in scope (triggers a compiler error). Is there some context available to both advices that I can store foo inside?

背景:我打算创建一个唯一标识符来引用该方法的这个特定调用，我需要在两个建议中访问它，因为我会将它包含在日志输出中.

Background: I intend to create a unique identifier to refer to this particular invocation of the method and I need access to it in both advices, since I will include it in logging output.

在我的建议类中存储参数不是一种选择(因为我希望它不知道建议).

Storing a parameter within my advised class is not an option (since I want it to be unaware of the advice).

推荐答案

你可以把它存储在一个成员变量中，但是你必须考虑线程安全.相反，我强烈建议使用 around 建议.

You could store it in a member variable, but then you have to think about thread safety. Instead I highly recommend to use an around advice.

Object around() : allMethods() {
    SomeObject foo = makeSomeObject();
    Object ret = proceed();
    foo.magic();
    return ret;
}

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