首先是internalAutoProxyCreator它是负责创建AOP对象 它本身是BPP, 它会在 registerBeanPostProcessors(beanFactory); 过程中被实例化org.springframework.context.support.PostProcessorRegistrationDelegate#registerBeanPostProcessors(org.springframework.beans.factory.config.ConfigurableListableBeanFactory, org.springframework.context.support.AbstractApplicationContext)/** * in short: * 1. 拿到所有实现 BeanPostProcessor 的 bean, 然后进行分类存起来 * 这有一点, Spring 对 BeanDefinition 分成三种角色: * 1. 用户定义的 Bean (ROLE_APPLICATION) * 2. 较复杂的 (ROLE_SUPPORT) 较复杂的? 通常是一个外部配置 * 3. Spring 内置的(ROLE_INFRASTRUCTURE) * 2. 如果实现了 BeanPostProcessor 则会实例化这个bean, 但注意这里只是注册,并不会调用BeanPostProcessor的相关方法 * * 另外 BeanPostProcessor 粗粒度太大, Spring 还细分一些子接口: * - SmartInstantiationAwareBeanPostProcessor 它提供了更高级的Bean实例化控制方法。主要作用在于允许对Bean的实例化过程进行更精细的控制和定制。 * - MergedBeanDefinitionPostProcessor 在合并Bean定义MergedBeanDefinition之后但在实例化Bean之前允许对合并后的Bean定义进行修改、调整或附加元数据。 * - DestructionAwareBeanPostProcessor 它允许在Bean被销毁之前例如容器关闭或特定作用域的Bean销毁执行一些操作。 */ public static void registerBeanPostProcessors( ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) { // WARNING: Although it may appear that the body of this method can be easily // refactored to avoid the use of multiple loops and multiple lists, the use // of multiple lists and multiple passes over the names of processors is // intentional. We must ensure that we honor the contracts for PriorityOrdered // and Ordered processors. Specifically, we must NOT cause processors to be // instantiated (via getBean() invocations) or registered in the ApplicationContext // in the wrong order. // // Before submitting a pull request (PR) to change this method, please review the // list of all declined PRs involving changes to PostProcessorRegistrationDelegate // to ensure that your proposal does not result in a breaking change: // https://github.com/spring-projects/spring-framework/issues?qPostProcessorRegistrationDelegateis%3Aclosedlabel%3A%22status%3Adeclined%22 /** * 拿到所有实现 BeanPostProcessor 的 bean名称 */ String[] postProcessorNames beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false); // Register BeanPostProcessorChecker that logs an info message when // a bean is created during BeanPostProcessor instantiation, i.e. when // a bean is not eligible for getting processed by all BeanPostProcessors. /** * 计算 BeanPostProcessor(BPP) 的总数. * 1 是什么操作? 原因是: 下一行,又加了一个 BeanPostProcessorChecker */ int beanProcessorTargetCount beanFactory.getBeanPostProcessorCount() 1 postProcessorNames.length; // BeanPostProcessorChecker 这个BeanPostProcessor, 没啥实际作用, 就是记录了一些日志; beanFactory.addBeanPostProcessor( new BeanPostProcessorChecker(beanFactory, postProcessorNames, beanProcessorTargetCount)); // Separate between BeanPostProcessors that implement PriorityOrdered, // Ordered, and the rest. /** * 对 BeanPostProcessor 进行分类存起来, 再调用, 每个集合分别是 * 1. priorityOrderedPostProcessors //有实现(PriorityOrdered)排序接口的 * 2. internalPostProcessors //Spring内部的bean, 见: Spring将bean分为三种角色 * 3. orderedPostProcessorNames //实现 Ordered 接口 * 4. nonOrderedPostProcessorNames //没有指定顺序, 无序的 */ ListBeanPostProcessor priorityOrderedPostProcessors new ArrayList(); ListBeanPostProcessor internalPostProcessors new ArrayList(); ListString orderedPostProcessorNames new ArrayList(); ListString nonOrderedPostProcessorNames new ArrayList(); for (String ppName : postProcessorNames) { if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) { /** * 注意, 若 bean 实现了 PriorityOrdered 接口, 则会优先实例化它; */ BeanPostProcessor pp beanFactory.getBean(ppName, BeanPostProcessor.class); priorityOrderedPostProcessors.add(pp); if (pp instanceof MergedBeanDefinitionPostProcessor) { internalPostProcessors.add(pp); } } else if (beanFactory.isTypeMatch(ppName, Ordered.class)) { orderedPostProcessorNames.add(ppName); } else { nonOrderedPostProcessorNames.add(ppName); } } // First, register the BeanPostProcessors that implement PriorityOrdered. sortPostProcessors(priorityOrderedPostProcessors, beanFactory); registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors); // Next, register the BeanPostProcessors that implement Ordered. ListBeanPostProcessor orderedPostProcessors new ArrayList(orderedPostProcessorNames.size()); for (String ppName : orderedPostProcessorNames) { BeanPostProcessor pp beanFactory.getBean(ppName, BeanPostProcessor.class); orderedPostProcessors.add(pp); if (pp instanceof MergedBeanDefinitionPostProcessor) { internalPostProcessors.add(pp); } } sortPostProcessors(orderedPostProcessors, beanFactory); registerBeanPostProcessors(beanFactory, orderedPostProcessors); /** * 注册所有常规BeanPostProcessors * 这里 getBean 实例化bean !; */ // Now, register all regular(常规) BeanPostProcessors. ListBeanPostProcessor nonOrderedPostProcessors new ArrayList(nonOrderedPostProcessorNames.size()); for (String ppName : nonOrderedPostProcessorNames) { BeanPostProcessor pp beanFactory.getBean(ppName, BeanPostProcessor.class); nonOrderedPostProcessors.add(pp); if (pp instanceof MergedBeanDefinitionPostProcessor) { internalPostProcessors.add(pp); } } registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors); /** * 最后, 注册所有 内置 BeanPostProcessor */ // Finally, re-register all internal BeanPostProcessors. sortPostProcessors(internalPostProcessors, beanFactory); registerBeanPostProcessors(beanFactory, internalPostProcessors); //最后再放一个 ApplicationListenerDetector 让它在最后 (不是重点, 见名应该是事件相关的) // Re-register post-processor for detecting inner beans as ApplicationListeners, // moving it to the end of the processor chain (for picking up proxies etc). beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext)); }DefaultBeanFactoryPointcutAdvisor 和 AspectJExpressionPointcut 对象internalAutoProxyCreator会在 postProcessBeforeInstantiation 回调中的org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#shouldSkip判断时实例化所有的 Advisor在实例化 Advisor 填充属性时也会把 AspectJExpressionPointcut 也实例化org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#postProcessBeforeInstantiationOverride public Object postProcessBeforeInstantiation(Class? beanClass, String beanName) { /** * 常规情况下: 这里只是检查下缓存和标记缓存 * 对于真正的AOP代理创建见: * {link AbstractAutoProxyCreator#postProcessAfterInitialization(java.lang.Object, java.lang.String)} */ Object cacheKey getCacheKey(beanClass, beanName); if (!StringUtils.hasLength(beanName) || !this.targetSourcedBeans.contains(beanName)) { /** * * 不管需不需要, 只要处理过了就缓存 * advisedBeans 这个变量, 缓存所有处理过的 bean名称; * value 为 boolean值, 如果为false 则不处理 */ if (this.advisedBeans.containsKey(cacheKey)) { return null; } /** * isInfrastructureClass 是否是基础功能类,即 AOP相关的几个类: * Advice.class Pointcut.class Advisor.class AopInfrastructureBean.class 都为true * * shouldSkip 判断时, 拿到容器的所有 Advisor, 并且实例化 getBean() 这个 Advisor */ if (isInfrastructureClass(beanClass) || shouldSkip(beanClass, beanName)) { this.advisedBeans.put(cacheKey, Boolean.FALSE); return null; } } // Create proxy here if we have a custom TargetSource. // Suppresses unnecessary default instantiation of the target bean: // The TargetSource will handle target instances in a custom fashion. TargetSource targetSource getCustomTargetSource(beanClass, beanName); if (targetSource ! null) { if (StringUtils.hasLength(beanName)) { this.targetSourcedBeans.add(beanName); } Object[] specificInterceptors getAdvicesAndAdvisorsForBean(beanClass, beanName, targetSource); Object proxy createProxy(beanClass, beanName, specificInterceptors, targetSource); this.proxyTypes.put(cacheKey, proxy.getClass()); return proxy; } return null; }TransactionInterceptort 对象是在internalAutoProxyCreator遇到需要增强代理的对象时, 这里是 bookService 去 getAdvicesAndAdvisorsForBean 查找到其匹配 bookService 的 Advisor这里若 Advisor 匹配, 会调用 getAdvice 获取其切面, 此时切面不存在则会实例化它org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#wrapIfNecessaryprotected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) { if (StringUtils.hasLength(beanName) this.targetSourcedBeans.contains(beanName)) { return bean; } if (Boolean.FALSE.equals(this.advisedBeans.get(cacheKey))) { return bean; } if (isInfrastructureClass(bean.getClass()) || shouldSkip(bean.getClass(), beanName)) { this.advisedBeans.put(cacheKey, Boolean.FALSE); return bean; } /** * 拿到所有匹配织入当前bean的 所有通知器(Advisor) * 做了三件事, 见: {link org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator#getAdvicesAndAdvisorsForBean(java.lang.Class, java.lang.String, org.springframework.aop.TargetSource)} * 1. 往返回 AspectJXXXAdvice列表数组0索引 插入一个{link org.springframework.aop.interceptor.ExposeInvocationInterceptor} 实例 * 方便传递参数用的 * * 2. 怎么匹配(Advisor)? * Advisor中的 AspectJExpressionPointcut 是实现 {link ClassFilter} 和 {link org.springframework.aop.MethodMatcher} 接口 * 一个进行类匹配, 一个进行方法匹配. Advisor 匹配会调用 getAdvice 获取其切面, 此时切面不存在则会实例化 * * 3. 排序, 基于 有向无环 图进行排序; 可能匹配到多个切面(aspect) * */ // Create proxy if we have advice. Object[] specificInterceptors getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null); if (specificInterceptors ! DO_NOT_PROXY) { /** *{link org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#advisedBeans} * 这个变量缓存所有处理过的 bean名称, value 为 boolean值, 如果为false 则不处理 */ this.advisedBeans.put(cacheKey, Boolean.TRUE);//缓存, 表示已处理 /** * 创建代理 * */ Object proxy createProxy( bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean)); this.proxyTypes.put(cacheKey, proxy.getClass()); return proxy; } this.advisedBeans.put(cacheKey, Boolean.FALSE); return bean; }汇总图