AOP中调用和执行的区别 [英] Difference between call and execution in AOP

问题描述

我试图尽可能简单地理解 AOP 中执行和调用之间的区别.据我所知， execution() 将在执行代码中添加一个连接点，因此在本例中为 HelloWorldSayer.sayHello()，但如果切入点是 call()，那么连接点将是 HelloWorldSayer.main().这是正确的吗?

I'm trying to understand the difference between execution and call in AOP as simply as possible. From what I gather, execution() will add a join point in the executing code, so HelloWorldSayer.sayHello() in this case, but if the pointcut was call(), then the join point will be HelloWorldSayer.main(). Is this correct?

public class HelloWorldSayer {
    public static void main (String[] args) {
        sayHello();
    }

    public static void sayHello() {
        System.out.println("Hello");
    }
}

public aspect World {
    public hello():
        execution(static void HelloWorldSayer.sayHello());

    after() hello() {
        System.out.println("Bye");
    }
}

推荐答案

如果我们再看一下 HelloWorldSayer 类，有 4 个连接点阴影(2 个执行切入点和 2 个调用切入点).

If we look at the HelloWorldSayer class again, there are 4 join point shadows (2 execution pointcuts and 2 call pointcuts).

换句话说，public static void main(String[] args)和public static void sayHello()指的是执行切入点.(HelloWorldSayer.)sayHello(); 和 System.out.println("Hello"); 指的是调用切入点.

In other words, public static void main (String[] args) and public static void sayHello() refer to the execution pointcut. (HelloWorldSayer.)sayHello(); and System.out.println("Hello"); refer to the call pointcut.

如果改变声明的切入点如下，切入点选择sayHello();

If you change the declared pointcut as follows, the pointcut selects sayHello();

public pointcut hello():
    call(static void HelloWorldSayer.sayHello());

另一方面，你改变声明的切入点如下，切入点选择sayHello方法声明public static void sayHello().

On the other hand, you change the declared pointcut as follows, the pointcut selects the sayHello method declaration public static void sayHello().

public pointcut hello():
    execution(static void HelloWorldSayer.sayHello());

最后，请阅读此答案以更好地了解 call() 和 execution():https://stackoverflow.com/a/18149106/904745

At last, please read this answer to get better understanding about call() and execution(): https://stackoverflow.com/a/18149106/904745

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