代碼片段:

org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#populateBean

if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
    for (BeanPostProcessor bp : getBeanPostProcessors()) {
        if (bp instanceof InstantiationAwareBeanPostProcessor) {
            InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
            //如果返回為 false, 則會終止屬性註入
            if (!ibp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) {
                return;
            }
        }
    }
}

需要註意一個問題, 如果返回值是 false , 那麼此處就回結束屬性註入方法: populateBean

這裡遍歷了容器中的後置處理器, 然後調用滿足條件的 postProcessAfterInstantiation() 方法.

boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException

通過調試, 很明瞭的能發現, 有三個後置處理器能滿足條件, 調用先後順序為:

1.ConfigurationClassPostProcessor$ImportAwareBeanPostProcessor

2.CommonAnnotationBeanPostProcessor

3.AutowiredAnnotationBeanPostProcessor

根據前面調用的 InstantiationAwareBeanPostProcessor 後置處理器, 大致可以推斷, 這裡估計啥也不會幹.

因為 spring 的流程還沒走完呢, 怎麼能終止呢!

ConfigurationClassPostProcessor$ImportAwareBeanPostProcessor

這裡是由其父類來完成的: 

org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter#postProcessAfterInstantiation

@Override
public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {
    return true;
}

啥也沒乾

CommonAnnotationBeanPostProcessor

@Override
public boolean postProcessAfterInstantiation(Object bean, String beanName) {
    return true;
}

啥也沒乾

AutowiredAnnotationBeanPostProcessor

由其父類完成:

org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter

@Override
public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {
    return true;
}

如我所想, 這裡啥也沒乾, 之所以這麼留著, 我估計是spring擴展用的