正文
入口
@EnableAspectJAutoProxy 这个注解是aop的入口，开启aop
@Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) @Documented @Import(AspectJAutoProxyRegistrar.class) public @interface EnableAspectJAutoProxy { 。。。。}
AspectJAutoProxyRegistrar.class
class AspectJAutoProxyRegistrar implements ImportBeanDefinitionRegistrar { AspectJAutoProxyRegistrar() { } public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) { //注册AnnotationAwareAspectJAutoProxyCreator.class到IOC容器 AopConfigUtils.registerAspectJAnnotationAutoProxyCreatorIfNecessary(registry); //获取@EnableAspectJAutoProxy注解 AnnotationAttributes enableAspectJAutoProxy = AnnotationConfigUtils.attributesFor(importingClassMetadata, EnableAspectJAutoProxy.class); if (enableAspectJAutoProxy != null) { if (enableAspectJAutoProxy.getBoolean("proxyTargetClass")) { AopConfigUtils.forceAutoProxyCreatorToUseClassProxying(registry); } if (enableAspectJAutoProxy.getBoolean("exposeProxy")) { AopConfigUtils.forceAutoProxyCreatorToExposeProxy(registry); } } } }
进入注册方法
AopConfigUtils.registerAspectJAnnotationAutoProxyCreatorIfNecessary(registry);
注册的方法
private static BeanDefinition registerOrEscalateApcAsRequired(Class<?> cls, BeanDefinitionRegistry registry, @Nullable Object source) { Assert.notNull(registry, "BeanDefinitionRegistry must not be null"); if (registry.containsBeanDefinition("org.springframework.aop.config.internalAutoProxyCreator")) { BeanDefinition apcDefinition = registry.getBeanDefinition("org.springframework.aop.config.internalAutoProxyCreator"); if (!cls.getName().equals(apcDefinition.getBeanClassName())) { int currentPriority = findPriorityForClass(apcDefinition.getBeanClassName()); int requiredPriority = findPriorityForClass(cls); if (currentPriority < requiredPriority) { apcDefinition.setBeanClassName(cls.getName()); } } return null; } else { RootBeanDefinition beanDefinition = new RootBeanDefinition(cls); beanDefinition.setSource(source); beanDefinition.getPropertyValues().add("order", -2147483648); beanDefinition.setRole(2); registry.registerBeanDefinition("org.springframework.aop.config.internalAutoProxyCreator", beanDefinition); return beanDefinition; } }
注册结果是：将下面这个类注入到IOC
1. beanId:org.springframework.aop.config.internalAutoProxyCreator 2. Class： AnnotationAwareAspectJAutoProxyCreator.class
再回过头看这个类AnnotationAwareAspectJAutoProxyCreator.class
由类图分析
可知，这个类实现BeanPostProcessor 接口
public interface BeanPostProcessor { @Nullable default Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { return bean; } @Nullable default Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException { return bean; } }
然后我们分开别查看这两个方法的实现
进入这个方法
public Object postProcessAfterInitialization(@Nullable Object bean, String beanName) { if (bean != null) { Object cacheKey = this.getCacheKey(bean.getClass(), beanName); if (this.earlyProxyReferences.remove(cacheKey) != bean) { //继续深入 return this.wrapIfNecessary(bean, beanName, cacheKey); } } return bean; }
继续深入
protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) { if (StringUtils.hasLength(beanName) && this.targetSourcedBeans.contains(beanName)) { return bean; } else if (Boolean.FALSE.equals(this.advisedBeans.get(cacheKey))) { //没有增强不用代理直接返回 return bean; } else if (!this.isInfrastructureClass(bean.getClass()) && !this.shouldSkip(bean.getClass(), beanName)) { //获取通知 Object[] specificInterceptors = this.getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, (TargetSource)null); if (specificInterceptors != DO_NOT_PROXY) { //判断是否需要代理（是否有通知），需要的话给一个true的标志 this.advisedBeans.put(cacheKey, Boolean.TRUE); //进行代理，继续深入 Object proxy = this.createProxy(bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean)); this.proxyTypes.put(cacheKey, proxy.getClass()); return proxy; } else { this.advisedBeans.put(cacheKey, Boolean.FALSE); return bean; } } else { //不需要设置false标志 this.advisedBeans.put(cacheKey, Boolean.FALSE); return bean; } }
继续深入
protected Object createProxy(Class<?> beanClass, @Nullable String beanName, @Nullable Object[] specificInterceptors, TargetSource targetSource) { if (this.beanFactory instanceof ConfigurableListableBeanFactory) { AutoProxyUtils.exposeTargetClass((ConfigurableListableBeanFactory)this.beanFactory, beanName, beanClass); } ProxyFactory proxyFactory = new ProxyFactory(); proxyFactory.copyFrom(this); if (!proxyFactory.isProxyTargetClass()) { if (this.shouldProxyTargetClass(beanClass, beanName)) { proxyFactory.setProxyTargetClass(true); } else { this.evaluateProxyInterfaces(beanClass, proxyFactory); } } Advisor[] advisors = this.buildAdvisors(beanName, specificInterceptors); proxyFactory.addAdvisors(advisors); proxyFactory.setTargetSource(targetSource); this.customizeProxyFactory(proxyFactory); proxyFactory.setFrozen(this.freezeProxy); if (this.advisorsPreFiltered()) { proxyFactory.setPreFiltered(true); } //继续深入 GO! GO!GO! return proxyFactory.getProxy(this.getProxyClassLoader()); }
最后进入这个方法
public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException { if (NativeDetector.inNativeImage() || !config.isOptimize() && !config.isProxyTargetClass() && !this.hasNoUserSuppliedProxyInterfaces(config)) { return new JdkDynamicAopProxy(config); } else { 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."); } else { //如果代理的是接口就JDK代理，如果不是接口就CGLIB代理 //jdk动态代理只能代理接口，cglib代理是基于继承实现的，所以被代理的类不行用final修饰 return (AopProxy)(!targetClass.isInterface() && !Proxy.isProxyClass(targetClass) ? new ObjenesisCglibAopProxy(config) : new JdkDynamicAopProxy(config)); } } }
最后就是执行invoke()方法。
本Spring版本为5.3.9
