Spring AOP：将目标传递给 Aspect

Question

我想捕捉实现处理器接口的类抛出的异常。在方面我需要访问处理器，这会引发异常。我定义了以下切入点：

@Pointcut("target(some.package.Processor) && args(message)")
  public void processor(Message message) {
}

和方面：

@AfterThrowing(pointcut="processor(message)", throwing="ex")
public void onExceptionInProcessor(Processor target, Exception ex, Message message) {
  // code skipped
}

但是，我得到以下异常：

Caused by: java.lang.IllegalArgumentException: error at ::0 formal unbound in pointcut 
    at org.aspectj.weaver.tools.PointcutParser.parsePointcutExpression(PointcutParser.java:301) ~[aspectjweaver-1.6.12.jar:1.6.12]
    at org.springframework.aop.aspectj.AspectJExpressionPointcut.buildPointcutExpression(AspectJExpressionPointcut.java:207) ~[spring-aop-3.1.0.RELEASE.jar:3.1.0.RELEASE]
    at org.springframework.aop.aspectj.AspectJExpressionPointcut.buildPointcutExpression(AspectJExpressionPointcut.java:193) ~[spring-aop-3.1.0.RELEASE.jar:3.1.0.RELEASE]
    at org.springframework.aop.aspectj.AspectJExpressionPointcut.checkReadyToMatch(AspectJExpressionPointcut.java:182) ~[spring-aop-3.1.0.RELEASE.jar:3.1.0.RELEASE]
    at org.springframework.aop.aspectj.AspectJExpressionPointcut.getClassFilter(AspectJExpressionPointcut.java:163) ~[spring-aop-3.1.0.RELEASE.jar:3.1.0.RELEASE]
    at org.springframework.aop.support.AopUtils.canApply(AopUtils.java:209) ~[spring-aop-3.1.0.RELEASE.jar:3.1.0.RELEASE]
    at org.springframework.aop.support.AopUtils.canApply(AopUtils.java:263) ~[spring-aop-3.1.0.RELEASE.jar:3.1.0.RELEASE]
    at org.springframework.aop.support.AopUtils.findAdvisorsThatCanApply(AopUtils.java:295) ~[spring-aop-3.1.0.RELEASE.jar:3.1.0.RELEASE]
    at org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator.findAdvisorsThatCanApply(AbstractAdvisorAutoProxyCreator.java:117) ~[spring-aop-3.1.0.RELEASE.jar:3.1.0.RELEASE]
    at org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator.findEligibleAdvisors(AbstractAdvisorAutoProxyCreator.java:87) ~[spring-aop-3.1.0.RELEASE.jar:3.1.0.RELEASE]
    at org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator.getAdvicesAndAdvisorsForBean(AbstractAdvisorAutoProxyCreator.java:68) ~[spring-aop-3.1.0.RELEASE.jar:3.1.0.RELEASE]
    at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.wrapIfNecessary(AbstractAutoProxyCreator.java:359) ~[spring-aop-3.1.0.RELEASE.jar:3.1.0.RELEASE]
    at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.postProcessAfterInitialization(AbstractAutoProxyCreator.java:322) ~[spring-aop-3.1.0.RELEASE.jar:3.1.0.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsAfterInitialization(AbstractAutowireCapableBeanFactory.java:407) ~[spring-beans-3.1.0.RELEASE.jar:3.1.0.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1461) ~[spring-beans-3.1.0.RELEASE.jar:3.1.0.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519) ~[spring-beans-3.1.0.RELEASE.jar:3.1.0.RELEASE]
    ... 58 common frames omitted

将 target 对象绑定到方面的正确方法是什么？我发现的唯一方法是绑定 JoinPoint，但它建议如下：

除非您特别需要这种反射访问，否则您应该使用 目标切入点指示符以获取该对象以获得更好的静态 打字和性能

有没有人知道如何做到这一点？

Answer 1

您的target 应该引用方法中的参数名称之一。比如说

@Pointcut("target(myProc) && args(message)")
public void processor(Processor myProc, Message message) {
}

将在myProc 变量中以类型安全的方式为您提供Processor。