我使用 Spring Boot 和 Spring Initializr 制作了一个简单的 Web 应用程序,并尝试编写 @Aspect 与 @左右建议。
当我添加自定义注释时 @RetryOnFailure 到 Controller 的端点方法 - 它可以工作,但是当我将此注释添加到 Controller 端点执行的 Controller 方法时 - 它不起作用。我花了很多时间来了解这种行为的原因,但没有任何结果。所以请帮忙。
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);
}
最佳答案
您犯了一个典型的 Spring AOP 初学者错误:您忘记了基于代理的 AOP 仅在代理方法从外部调用时才有效,而不是通过 this
(避免代理)。但是内部电话inTry()
与 this.inTry()
相同.因此,方面永远不会触发 inTry
你必须像这样重新排列你的代码:
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);
}
}
我也稍微改变了外观,以便
@annotation()
绑定(bind)到通知参数, 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());
}
}
}
}
现在它可以工作了,控制台日志说:
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
关于java - Spring AOP : aspect @Around doesn't work,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/42733826/