上一章中講解了：BeanPostProcessorFactory方法的調用，給BeanFactory中引入類BeanPostProcessor類。這一章，我們來看看spring容器在創建時，如何添加BeanPostProcessor。

1. registerBeanPostProcessors：注冊BeanPostProcessor到容器

public static void registerBeanPostProcessors( ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
    //獲取BeanFactory中的BeanPostProcessor類
    String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);
    
    //添加了BeanPostProcessorChecker
    beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));

    //將BeanPostProcessor按照PriorityOrdered->Orderd->Normal順序來整理BeanPostProcessor
    List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanPostProcessor>();
    List<BeanPostProcessor> internalPostProcessors = new ArrayList<BeanPostProcessor>();
    List<String> orderedPostProcessorNames = new ArrayList<String>();
    List<String> nonOrderedPostProcessorNames = new ArrayList<String>();
    
     ...
    // 首先排序PriorityOrdered的BeanPostProcessor，然后注冊到BeanFactory中
    sortPostProcessors(beanFactory, priorityOrderedPostProcessors);
    registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);

    // 接下來是Ordered->normal->internal

    //最后添加了ApplicationListenerDetector的BeanPostProcessor
    beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));

}

2. addBeanPostProcessor

將BeanPostProcessor存放在List中，以備后續創建Bean時使用。

@Override
    public void addBeanPostProcessor(BeanPostProcessor beanPostProcessor) {
        Assert.notNull(beanPostProcessor, "BeanPostProcessor must not be null");
        this.beanPostProcessors.remove(beanPostProcessor);
        this.beanPostProcessors.add(beanPostProcessor);
        if (beanPostProcessor instanceof InstantiationAwareBeanPostProcessor) {
            this.hasInstantiationAwareBeanPostProcessors = true;
        }
        if (beanPostProcessor instanceof DestructionAwareBeanPostProcessor) {
            this.hasDestructionAwareBeanPostProcessors = true;
        }
    }