Aspectj：lambda表达式的切入点

虚拟按钮类,复制我们需要的Vaadin部分：

package de.scrum_master.app;

public class Button {
    private ClickListener listener;

    public void addClickListener(ClickListener listener) {
        this.listener = listener;
    }

    public void click() {
        System.out.println("Clicking button");
        listener.buttonClick(new ClickEvent());
    }

    public static class ClickEvent {}

    public static interface ClickListener {
        public void buttonClick(ClickEvent clickEvent);
    }
}

司机申请：

package de.scrum_master.app;

public class Application {
    protected static void doSomething() {}

    public static void main(String[] args) {
        Button button = new Button();
        button.addClickListener(new Button.ClickListener() {
            @Override
            public void buttonClick(Button.ClickEvent clickEvent) {
                doSomething();
            }
        });
        button.click();

        button = new Button();
        button.addClickListener(clickEvent -> doSomething());
        button.click();
    }
}

如您所见,创建了两个按钮实例,一个具有经典的匿名类侦听器,另一个具有lambda侦听器.单击这两个按钮,因此控制台日志如下所示：

Clicking button
Clicking button

方面：

package de.scrum_master.aspect;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;

@Aspect
public class ButtonClickLogger {
    @Before("execution(public void *..Button.ClickListener.buttonClick(*..Button.ClickEvent))")
    public void logButtonClick(JoinPoint thisJoinPoint) {
        System.out.println("Caught button click: " + thisJoinPoint);
    }

    @Before("within(*..Application)")
    public void logAllInListener(JoinPoint thisJoinPoint) {
        System.out.println("  " + thisJoinPoint);
    }

    @Before("execution(void *..lambda*(*..Button.ClickEvent))")
    public void logButtonClickLambda(JoinPoint thisJoinPoint) {
        System.out.println("Caught button click (lambda): " + thisJoinPoint);
    }
}

第一个建议使用类似于你的切入点.它只能拦截经典的侦听器声明.

第二个建议是用于调试目的,并记录驱动程序应用程序中的所有连接点,以显示这里发生了什么.

最后,但并非最不重要的是,第三个建议显示了拦截基于lambda的侦听器的解决方法,依赖于从调试输出获取的有关lambdas的Java编译器命名的知识.这不是很好,但目前它的工作原理.请注意,buttonClick(..)的lambda版本不是公共的,所以它只是void * .. lambda *,而不是public void * .. lambda *.

使用AspectJ的控制台输出：

staticinitialization(de.scrum_master.app.Application.<clinit>)
  execution(void de.scrum_master.app.Application.main(String[]))
  call(de.scrum_master.app.Button())
  call(de.scrum_master.app.Application.1())
  staticinitialization(de.scrum_master.app.Application.1.<clinit>)
  preinitialization(de.scrum_master.app.Application.1())
  initialization(de.scrum_master.app.Application.1())
  initialization(de.scrum_master.app.Button.ClickListener())
  execution(de.scrum_master.app.Application.1())
  call(void de.scrum_master.app.Button.addClickListener(Button.ClickListener))
  call(void de.scrum_master.app.Button.click())
Clicking button
Caught button click: execution(void de.scrum_master.app.Application.1.buttonClick(Button.ClickEvent))
  execution(void de.scrum_master.app.Application.1.buttonClick(Button.ClickEvent))
  call(void de.scrum_master.app.Application.doSomething())
  execution(void de.scrum_master.app.Application.doSomething())
  call(de.scrum_master.app.Button())
  call(void de.scrum_master.app.Button.addClickListener(Button.ClickListener))
  call(void de.scrum_master.app.Button.click())
Clicking button
  execution(void de.scrum_master.app.Application.lambda$0(Button.ClickEvent))
Caught button click (lambda): execution(void de.scrum_master.app.Application.lambda$0(Button.ClickEvent))
  call(void de.scrum_master.app.Application.doSomething())
  execution(void de.scrum_master.app.Application.doSomething())

更新：AspectJ现在有一个相应的Bugzilla issue.我刚刚创建了它.它还指出了最近对邮件列表的讨论.