繼續上一篇的話題，在《Spring原始碼閱讀4.1-Aspecjt AOP之獲取Adivsor》，我們說獲取了所有的AspectJ以及其Advisor，其中每個Advisor都和其Aspectj類的表示式一起快取到了陣列中，以便後續直接使用。在這裡要補充一下InstantiationModelAwarePointcutAdvisorImpl物件的初始化。只上原始碼：

public InstantiationModelAwarePointcutAdvisorImpl(AspectJAdvisorFactory af, AspectJExpressionPointcut ajexp,
			MetadataAwareAspectInstanceFactory aif, Method method, int declarationOrderInAspect, String aspectName) {

		this.declaredPointcut = ajexp;
		this.method = method;
		this.atAspectJAdvisorFactory = af;
		this.aspectInstanceFactory = aif;
		this.declarationOrder = declarationOrderInAspect;
		this.aspectName = aspectName;

		if (aif.getAspectMetadata().isLazilyInstantiated()) {
			// Static part of the pointcut is a lazy type.
			Pointcut preInstantiationPointcut =
					Pointcuts.union(aif.getAspectMetadata().getPerClausePointcut(), this.declaredPointcut);

			// Make it dynamic: must mutate from pre-instantiation to post-instantiation state.
			// If it's not a dynamic pointcut, it may be optimized out
			// by the Spring AOP infrastructure after the first evaluation.
			this.pointcut = new PerTargetInstantiationModelPointcut(this.declaredPointcut, preInstantiationPointcut, aif);
			this.lazy = true;
		}
		else {
			// A singleton aspect.
			this.instantiatedAdvice = instantiateAdvice(this.declaredPointcut);
			this.pointcut = declaredPointcut;
			this.lazy = false;
		}
	}
 

在instantiateAdivice方法中，根據不同的型別建立了不同的Advice物件。

@Override
	public Advice getAdvice(Method candidateAdviceMethod, AspectJExpressionPointcut ajexp,
			MetadataAwareAspectInstanceFactory aif, int declarationOrderInAspect, String aspectName) {

		Class<?> candidateAspectClass = aif.getAspectMetadata().getAspectClass();
		validate(candidateAspectClass);

		AspectJAnnotation<?> aspectJAnnotation =
				AbstractAspectJAdvisorFactory.findAspectJAnnotationOnMethod(candidateAdviceMethod);
		if (aspectJAnnotation == null) {
			return null;
		}

		// If we get here, we know we have an AspectJ method.
		// Check that it's an AspectJ-annotated class
		if (!isAspect(candidateAspectClass)) {
			throw new AopConfigException("Advice must be declared inside an aspect type: " +
					"Offending method '" + candidateAdviceMethod + "' in class [" +
					candidateAspectClass.getName() + "]");
		}

		if (logger.isDebugEnabled()) {
			logger.debug("Found AspectJ method: " + candidateAdviceMethod);
		}

		AbstractAspectJAdvice springAdvice;

		switch (aspectJAnnotation.getAnnotationType()) {
			case AtBefore:
				springAdvice = new AspectJMethodBeforeAdvice(candidateAdviceMethod, ajexp, aif);
				break;
			case AtAfter:
				springAdvice = new AspectJAfterAdvice(candidateAdviceMethod, ajexp, aif);
				break;
			case AtAfterReturning:
				springAdvice = new AspectJAfterReturningAdvice(candidateAdviceMethod, ajexp, aif);
				AfterReturning afterReturningAnnotation = (AfterReturning) aspectJAnnotation.getAnnotation();
				if (StringUtils.hasText(afterReturningAnnotation.returning())) {
					springAdvice.setReturningName(afterReturningAnnotation.returning());
				}
				break;
			case AtAfterThrowing:
				springAdvice = new AspectJAfterThrowingAdvice(candidateAdviceMethod, ajexp, aif);
				AfterThrowing afterThrowingAnnotation = (AfterThrowing) aspectJAnnotation.getAnnotation();
				if (StringUtils.hasText(afterThrowingAnnotation.throwing())) {
					springAdvice.setThrowingName(afterThrowingAnnotation.throwing());
				}
				break;
			case AtAround:
				springAdvice = new AspectJAroundAdvice(candidateAdviceMethod, ajexp, aif);
				break;
			case AtPointcut:
				if (logger.isDebugEnabled()) {
					logger.debug("Processing pointcut '" + candidateAdviceMethod.getName() + "'");
				}
				return null;
			default:
				throw new UnsupportedOperationException(
						"Unsupported advice type on method " + candidateAdviceMethod);
		}

		// Now to configure the advice...
		springAdvice.setAspectName(aspectName);
		springAdvice.setDeclarationOrder(declarationOrderInAspect);
		String[] argNames = this.parameterNameDiscoverer.getParameterNames(candidateAdviceMethod);
		if (argNames != null) {
			springAdvice.setArgumentNamesFromStringArray(argNames);
		}
		springAdvice.calculateArgumentBindings();
		return springAdvice;
	}
 

我們回到AspectJAwareAdvisorAutoProxyCreator的父類AbstractAdvisorAutoProxyCreator的findEligibleAdvisors方法上來

/**
	 * Find all eligible Advisors for auto-proxying this class.
	 * @param beanClass the clazz to find advisors for
	 * @param beanName the name of the currently proxied bean
	 * @return the empty List, not {@code null},
	 * if there are no pointcuts or interceptors
	 * @see #findCandidateAdvisors
	 * @see #sortAdvisors
	 * @see #extendAdvisors
	 */
	protected List<Advisor> findEligibleAdvisors(Class<?> beanClass, String beanName) {
		List<Advisor> candidateAdvisors = findCandidateAdvisors();
		List<Advisor> eligibleAdvisors = findAdvisorsThatCanApply(candidateAdvisors, beanClass, beanName);
		extendAdvisors(eligibleAdvisors);
		if (!eligibleAdvisors.isEmpty()) {
			eligibleAdvisors = sortAdvisors(eligibleAdvisors);
		}
		return eligibleAdvisors;
	}
 

在上文中我們已經說過了所有候選Advisor的獲取，下面就要從這些增強中獲取可以適用到目標物件的Advisor，跟蹤下原始碼：

	/**
	 * Search the given candidate Advisors to find all Advisors that
	 * can apply to the specified bean.
	 * @param candidateAdvisors the candidate Advisors
	 * @param beanClass the target's bean class
	 * @param beanName the target's bean name
	 * @return the List of applicable Advisors
	 * @see ProxyCreationContext#getCurrentProxiedBeanName()
	 */
	protected List<Advisor> findAdvisorsThatCanApply(
			List<Advisor> candidateAdvisors, Class<?> beanClass, String beanName) {

		ProxyCreationContext.setCurrentProxiedBeanName(beanName);
		try {
			return AopUtils.findAdvisorsThatCanApply(candidateAdvisors, beanClass);
		}
		finally {
			ProxyCreationContext.setCurrentProxiedBeanName(null);
		}
	}

  ProxyCreationContext.setCurrentProxiedBeanName(beanName);設定了beanName，這裡使用了ThreadLocal，用執行緒物件做key，只可以儲存一個值。使用AopUtiles獲取適用的Advisor,我們布深究其實現方法，到這裡適用的Advisor已經獲取到，直接建立代理物件。

protected Object createProxy(
			Class<?> beanClass, String beanName, Object[] specificInterceptors, TargetSource targetSource) {

		ProxyFactory proxyFactory = new ProxyFactory();
		proxyFactory.copyFrom(this);

		if (!proxyFactory.isProxyTargetClass()) {
			if (shouldProxyTargetClass(beanClass, beanName)) {
				proxyFactory.setProxyTargetClass(true);
			}
			else {
				evaluateProxyInterfaces(beanClass, proxyFactory);
			}
		}

		Advisor[] advisors = buildAdvisors(beanName, specificInterceptors);
		for (Advisor advisor : advisors) {
			proxyFactory.addAdvisor(advisor);
		}

		proxyFactory.setTargetSource(targetSource);
		customizeProxyFactory(proxyFactory);

		proxyFactory.setFrozen(this.freezeProxy);
		if (advisorsPreFiltered()) {
			proxyFactory.setPreFiltered(true);
		}

		return proxyFactory.getProxy(getProxyClassLoader());
	}

回到wrapIfNecessary方法：// Create proxy if we have advice.
  Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
  if (specificInterceptors != DO_NOT_PROXY) {
   this.advisedBeans.put(cacheKey, Boolean.TRUE);
   Object proxy = createProxy(bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));
   this.proxyTypes.put(cacheKey, proxy.getClass());
   return proxy;
  }

	/**
	 * Create a new proxy according to the settings in this factory.
	 * <p>Can be called repeatedly. Effect will vary if we've added
	 * or removed interfaces. Can add and remove interceptors.
	 * <p>Uses the given class loader (if necessary for proxy creation).
	 * @param classLoader the class loader to create the proxy with
	 * (or {@code null} for the low-level proxy facility's default)
	 * @return the proxy object
	 */
	public Object getProxy(ClassLoader classLoader) {
		return createAopProxy().getProxy(classLoader);
	}

這裡使用了DefaultAopProxyFactory物件來返回代理工具物件，簡單來說，就是根據條件決定返回JdkDynamicAopProxy還是ObjenesisCglibAopProxy

@Override
	public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException {
		if (config.isOptimize() || config.isProxyTargetClass() || hasNoUserSuppliedProxyInterfaces(config)) {
			Class<?> targetClass = config.getTargetClass();
			if (targetClass == null) {
				throw new AopConfigException("TargetSource cannot determine target class: " +
						"Either an interface or a target is required for proxy creation.");
			}
			if (targetClass.isInterface() || Proxy.isProxyClass(targetClass)) {
				return new JdkDynamicAopProxy(config);
			}
			return new ObjenesisCglibAopProxy(config);
		}
		else {
			return new JdkDynamicAopProxy(config);
		}
	}

然後用返回的代理工具類去例項化目標代理類。先看下JDK代理型別，呼叫其getProxy方法

	@Override
	public Object getProxy(ClassLoader classLoader) {
		if (logger.isDebugEnabled()) {
			logger.debug("Creating JDK dynamic proxy: target source is "
					+ this.advised.getTargetSource());
		}
		Class<?>[] proxiedInterfaces = AopProxyUtils.completeProxiedInterfaces(this.advised);
		findDefinedEqualsAndHashCodeMethods(proxiedInterfaces);
		return Proxy.newProxyInstance(classLoader, proxiedInterfaces, this);
	}