Springboot aop源码解析

1.spring.factories中有AopAutoConfiguration类

@Configuration @ConditionalOnClass({ EnableAspectJAutoProxy.class, Aspect.class, Advice.class }) @ConditionalOnProperty(prefix = "spring.aop", name = "auto", havingValue = "true", matchIfMissing = true) public class AopAutoConfiguration { @Configuration @EnableAspectJAutoProxy(proxyTargetClass = false) @ConditionalOnProperty(prefix = "spring.aop", name = "proxy-target-class", havingValue = "false", matchIfMissing = true) public static class JdkDynamicAutoProxyConfiguration { } @Configuration @EnableAspectJAutoProxy(proxyTargetClass = true) @ConditionalOnProperty(prefix = "spring.aop", name = "proxy-target-class", havingValue = "true", matchIfMissing = false) public static class CglibAutoProxyConfiguration { } }

2.@EnableAspectJAutoProxy注解导入了 AspectJAutoProxyRegistrar类该类实现了ImportBeanDefinitionRegistrar类

class AspectJAutoProxyRegistrar implements ImportBeanDefinitionRegistrar { AspectJAutoProxyRegistrar() { } public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) { AopConfigUtils.registerAspectJAnnotationAutoProxyCreatorIfNecessary(registry);//在这里导入了AnnotationAwareAspectJAutoProxyCreator类，该类是关键 AnnotationAttributes enableAspectJAutoProxy = AnnotationConfigUtils.attributesFor(importingClassMetadata, EnableAspectJAutoProxy.class); if (enableAspectJAutoProxy.getBoolean("proxyTargetClass")) { AopConfigUtils.forceAutoProxyCreatorToUseClassProxying(registry); } if (enableAspectJAutoProxy.getBoolean("exposeProxy")) { AopConfigUtils.forceAutoProxyCreatorToExposeProxy(registry); } } }

3.AnnotationAwareAspectJAutoProxyCreator又是SmartInstantiationAwareBeanPostProcessor的子类，所以该扩展接口正是 aop 实现的入口。

public static BeanDefinition registerAspectJAnnotationAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry, Object source) { return registerOrEscalateApcAsRequired(AnnotationAwareAspectJAutoProxyCreator.class, registry, source);//导入成功 } @Override public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException { Object cacheKey = getCacheKey(beanClass, beanName); if (!StringUtils.hasLength(beanName) || !this.targetSourcedBeans.contains(beanName)) { //advisedBeans用于存储不可代理的bean，如果包含直接返回 if (this.advisedBeans.containsKey(cacheKey)) { return null; } //判断当前bean是否可以被代理，然后存入advisedBeans if (isInfrastructureClass(beanClass) || shouldSkip(beanClass, beanName)) {//进入分析 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. //到这里说明该bean可以被代理，所以去获取自定义目标类，如果没有定义，则跳过。 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()); //如果最终可以获得代理类，则返回代理类，直接执行实例化后置通知方法 return proxy; } return null; }