java - @AfterThrowing 在 Spring 中的不同行为

Question

我有以下奇怪的行为。

当我使用命名切入点时，建议的方法在 @AfterThrowing 的主体之前运行带注释的方法。但是如果我使用内联切入点 @AfterThrowing带注释的首先运行。

为什么会这样？

这是代码:

@Component
@Aspect
public class CustomAspect {

    @AfterThrowing(pointcut = "execution(* throwAnException(..))", throwing = "exception")
    public void adviceForExceptionThrowing(Exception exception) {
        System.out.println("###### " + exception.getMessage() + " ######");
    }

}

结果:

INFO: Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@5a10411: startup date [Wed Jun 14 15:51:26 EEST 2017]; root of context hierarchy
###### Some message from the exception ######
Exception in thread "main" java.lang.Exception: Some message from the exception

<小时/>

第二个结果:

@Component
@Aspect
public class CustomAspect {

    @Pointcut("execution(* throwAnException(..))")
    private void pointcutForException() {
    }

    @AfterThrowing(pointcut = "pointcutForException()", throwing = "exception")
    public void adviceForExceptionThrowing(Exception exception) {
        System.out.println("###### " + exception.getMessage() + " ######");
    }

}

我们得到:

INFO: Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@5a10411: startup date [Wed Jun 14 15:54:38 EEST 2017]; root of context hierarchy
Exception in thread "main" java.lang.Exception: Some message from the exception
    at blog.codingideas.aspects.SomeBean.throwAnException(SomeBean.java:13)
    at blog.codingideas.aspects.SomeBean$$FastClassBySpringCGLIB$$97c62a5f.invoke(<generated>)
    at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:738)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
    at org.springframework.aop.aspectj.AspectJAfterThrowingAdvice.invoke(AspectJAfterThrowingAdvice.java:62)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:673)
    at blog.codingideas.aspects.SomeBean$$EnhancerBySpringCGLIB$$985c5826.throwAnException(<generated>)
    at blog.codingideas.ApplicationMain.main(ApplicationMain.java:13)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)
###### Some message from the exception ######

Answer 1

您的代码按预期工作。 @AfterThrown 通知在异常抛出后已执行。

棘手的是 System.out.println。它在底层调用 PrintStream。这是一个缓冲流。缓冲流在填满后或当您显式调用其刷新时被写入输出(控制台)。

因此，在您的情况下，这取决于堆栈填充量的内部动态以及在其他线程打印异常堆栈跟踪之前能够执行多少打印语句。

附注尝试运行每个解决方案几次，您会发现###### 来自异常 ###### 的一些消息正在主堆栈跟踪之前和之后以随机顺序打印。