Spring AOP:aspect@around不起作用

Question

项目地址：https://github.com/zalizko/spring-aop-playground

@Aspect
@Component
public final class MethodRepeater {

    @Around("execution(* *(..)) && @annotation(RetryOnFailure)")
    public Object wrap(final ProceedingJoinPoint joinPoint) throws Throwable {
        // code is here
    }
}

所以，我的目标是：

@RequestMapping
public String index() {
    inTry();
    return "OK";
}


@RetryOnFailure(attempts = 3, delay = 2, unit = TimeUnit.SECONDS)
public void inTry() {
    throw new RuntimeException("Exception in try " + ++counter);
}

Answer 1

您犯了一个典型的Spring AOP初学者的错误：您忘记了基于代理的AOP只有在从外部调用代理方法时才起作用，而不是通过这个（避免使用代理）。但是内部调用intry()与this.intry()相同。因此，intry不会触发方面，您必须像这样重新排列代码：

package spring.aop;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.concurrent.TimeUnit;

@RestController("/")
public class HomeController {

    static int counter = 0;

    @RequestMapping
    @RetryOnFailure(attempts = 3, delay = 2, unit = TimeUnit.SECONDS)
    public String index() {
        throw new RuntimeException("Exception in try " + ++counter);
    }
}

我还稍微改变了一下方面，以便

• 避免反射，直接通过@annotation()，
将注释绑定到advice参数
• 在触发通知和
时记录连接点
• 在try#3上返回“OK”（只是为了好玩，没有必要）。

package spring.aop;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.springframework.stereotype.Component;

@Aspect
@Component
public final class MethodRepeater {

    @Around("execution(* spring.aop..*(..)) && @annotation(retryOnFailure)")
    public Object wrap(final ProceedingJoinPoint joinPoint, RetryOnFailure retryOnFailure) throws Throwable {
        System.out.println(joinPoint);
        return proceed(joinPoint, retryOnFailure);
    }

    private Object proceed(ProceedingJoinPoint joinPoint, RetryOnFailure retryOnFailure) throws Throwable {
        int attempt = 1;
        while (true) {
            try {
                return joinPoint.proceed();
            } catch (final Throwable ex) {
                System.out.println("Try #" + attempt + " failed: " + ex);
                if (++attempt >= retryOnFailure.attempts())
                    return "OK";
                if (retryOnFailure.delay() > 0L)
                    retryOnFailure.unit().sleep(retryOnFailure.delay());
            }
        }
    }
}

execution(String spring.aop.HomeController.index())
Try #1 failed: java.lang.RuntimeException: Exception in try 1
Try #2 failed: java.lang.RuntimeException: Exception in try 2