什么是BeanFactory的定制化呢？先来看看这个接口：BeanFactoryPostProcessor

public interface BeanFactoryPostProcessor {void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException;}

使用的时候可以得到beanFactory，那么beanFactory中的所有东西都能得到。beanFactory有spring提供的默认配置。比如实例化策略呀，类加载器，资源加载器，bean名称的生成器等等。当然包括注册bf的map和实例化bean的map。这样我们可以设置我们们自定义的配置。或者手动向IOC容器中添加bf或者实例，不在通过spring。

还有一层意思是当我们调用到这个接口的时候，我们向IOC注册的bean,都已经解析为BeaDefinition保存再beanFactory中了。

spring是何时调用的这个接口呢？

找到refresh方法，找到这个方法：org.springframework.context.support.AbstractApplicationContext#invokeBeanFactoryPostProcessors

	public static void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {// beanFactoryPostProcessors是spring内部直接添加的处理器// 所以得先处理spring内部的。Set<String> processedBeans = new HashSet<>();// 通常beanFactory 都会是BeanDefinitionRegistry，// 既是BeanDefinition注册器，又是bean对象的实例化保存工厂。if (beanFactory instanceof BeanDefinitionRegistry) {BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {BeanDefinitionRegistryPostProcessor registryProcessor =(BeanDefinitionRegistryPostProcessor) postProcessor;// 如果是BeanDefinitionRegistryPostProcessor就先调用postProcessBeanDefinitionRegistry方法。registryProcessor.postProcessBeanDefinitionRegistry(registry);registryProcessors.add(registryProcessor);}else {regularPostProcessors.add(postProcessor);}}// 上面都是先处理spring内部直接添加的处理器，这个处理器不会走spring的实例化过程// 下面才是走spring实例化过程的。List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();// 1. 先找PriorityOrdered接口的BeanDefinitionRegistryPostProcessor// 实现PriorityOrdered有高优先级String[] postProcessorNames =beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);for (String ppName : postProcessorNames) {if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {// 这里实例化了处理器currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));processedBeans.add(ppName);}}// 排序是根据order值排序的，从小到大，越小优先级越高。sortPostProcessors(currentRegistryProcessors, beanFactory);registryProcessors.addAll(currentRegistryProcessors);//调用postProcessBeanDefinitionRegistry方法。invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);currentRegistryProcessors.clear();// 2. 还是同样的逻辑：只不过是找Ordered接口的BeanDefinitionRegistryPostProcessorpostProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);for (String ppName : postProcessorNames) {if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));processedBeans.add(ppName);}}sortPostProcessors(currentRegistryProcessors, beanFactory);registryProcessors.addAll(currentRegistryProcessors);invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);currentRegistryProcessors.clear();// 最后找的是普通的boolean reiterate = true;while (reiterate) {reiterate = false;postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);for (String ppName : postProcessorNames) {if (!processedBeans.contains(ppName)) {currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));processedBeans.add(ppName);reiterate = true;}}sortPostProcessors(currentRegistryProcessors, beanFactory);registryProcessors.addAll(currentRegistryProcessors);invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);currentRegistryProcessors.clear();}// 由于BeanDefinitionRegistryPostProcessor extends BeanFactoryPostProcessor// 所以这里调用了BeanFactoryPostProcessor的方法invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);}else {// Invoke factory processors registered with the context instance.invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);}//以上是处理BeanDefinitionRegistryPostProcessor ，下面是处理BeanFactoryPostProcessor// 还是同样的逻辑：String[] postProcessorNames =beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,// Ordered, and the rest.List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();List<String> orderedPostProcessorNames = new ArrayList<>();List<String> nonOrderedPostProcessorNames = new ArrayList<>();for (String ppName : postProcessorNames) {if (processedBeans.contains(ppName)) {// skip - already processed in first phase above}else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));}else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {orderedPostProcessorNames.add(ppName);}else {nonOrderedPostProcessorNames.add(ppName);}}// First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.sortPostProcessors(priorityOrderedPostProcessors, beanFactory);invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);// Next, invoke the BeanFactoryPostProcessors that implement Ordered.List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());for (String postProcessorName : orderedPostProcessorNames) {orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));}sortPostProcessors(orderedPostProcessors, beanFactory);invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);// Finally, invoke all other BeanFactoryPostProcessors.List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size());for (String postProcessorName : nonOrderedPostProcessorNames) {nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));}invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);// Clear cached merged bean definitions since the post-processors might have// modified the original metadata, e.g. replacing placeholders in values...beanFactory.clearMetadataCache();}

该方法会先处理BeanDefinitionRegistryPostProcessor接口的类。

1. 找到实现了PriorityOrdered接口的，根据order值从小到大排序。执行postProcessBeanDefinitionRegistry方法。
2. 找到实现了Ordered接口的，根据order值从小到大排序，执行postProcessBeanDefinitionRegistry方法。
3. 找到普通的，依旧排序，按什么排序呢？会找Order注解，根据注解的值从小到大排序；如果没有order注解，就默认是只是Integer.MAX_VALUE，最小优先级。 执行postProcessBeanDefinitionRegistry方法
4. postProcessBeanDefinitionRegistry执行完成后，以上的所有实例会执行postProcessBeanFactory，因为BeanDefinitionRegistryPostProcessor extends BeanFactoryPostProcessor，要执行BeanFactoryPostProcessor的方法。

执行完BeanDefinitionRegistryPostProcessor类型的，下面才是执行BeanFactoryPostProcessor类型的。
逻辑是一样的。

所以如果你想定制BeanFactory中的处理器，那么实现BeanFactoryPostProcessor接口，如果你想更改beanDefinition中的值，实现BeanDefinitionRegistryPostProcessor即可偶是更好的选择。