spring使用BeanPostProcesor實現AOP源碼分析

源碼

AbstractApplicationContext#public void refresh() throws BeansException, IllegalStateException {
    finishBeanFactoryInitialization(beanFactory);
};
protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
    beanFactory.preInstantiateSingletons();
}
DefaultListableBeanFactory#public void preInstantiateSingletons() throws BeansException {
    getBean(beanName);
}
AbstractBeanFactory#public Object getBean(String name) throws BeansException {
    return doGetBean(name, null, null, false);
}
protected <T> T doGetBean() {
    return createBean(beanName, mbd, args);
}
AbstractAutowireCapableBeanFactory#protected Object createBean(String beanName, RootBeanDefinition mbd, Object[] args) throws BeanCreationException {
    Object beanInstance = doCreateBean(beanName, mbdToUse, args);
}
protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final Object[] args)
            throws BeanCreationException {
    exposedObject = initializeBean(beanName, exposedObject, mbd);        
}
protected Object initializeBean(final String beanName, final Object bean, RootBeanDefinition mbd) {
    // 第二個參數bean，此時已經實例化好了，也已經屬性注入了
    wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
}
public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName) {
    result = beanProcessor.postProcessAfterInitialization(result, beanName);
}
interface BeanPostProcessor#Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException;
AbstractAutoProxyCreator#public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if (bean != null) {
            Object cacheKey = getCacheKey(bean.getClass(), beanName);
            //  判斷是否須要對此Bean生成代理
            if (!this.earlyProxyReferences.contains(cacheKey)) {
                return wrapIfNecessary(bean, beanName, cacheKey);
            }
        }
        return bean;
    }
protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {
    if (beanName != null && 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;
    }

    // Create proxy if we have advice.
    Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
    if (specificInterceptors != DO_NOT_PROXY) {
        this.advisedBeans.put(cacheKey, Boolean.TRUE);
        // 生成代理類
        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;
}