refresh() -> invokeBeanFactoryPostProcessors()

调用各种BeanFactory处理器，如：

解析占位符${}中对应属性值的替换工作

扩充

通常如果想对BeanFactory中的数据进行修改时可以通过实现BeanFactoryPostProcessor来进行实现

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

针对BeanFactory

同理，如果想要修改BeanDefinition中的信息时可以实现BeanDefinitionRegistryPostProcessor进行操作

public interface BeanDefinitionRegistryPostProcessor extends BeanFactoryPostProcessor {void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException;
}

针对BeanDefinition，而BeanFactory已包含；BeanDefinitionRegistry的作用为对BeanDefinition的增删改查操作

如果一个类实现了BeanDefinitionRegistryPostProcessor，那么他的postProcessBeanFactory()方法可以跟其他的BeanFactoryPostProcessor一起执行

所有后置Registry的对象都是对前面名称对象的增删改查的操作

有关IOC中对象执行顺序的说明

PriorityOrdered > Ordered > 没有实现任何排序接口的对象

public interface PriorityOrdered extends Ordered {}public interface Ordered {int HIGHEST_PRECEDENCE = Integer.MIN_VALUE;int LOWEST_PRECEDENCE = Integer.MAX_VALUE;int getOrder();
}

invokeBeanFactoryPostProcessors()

实例化并且调用所有已经注册了的BeanFactoryPostProcessor，遵循指明的顺序

protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {// 获取到当前应用程序上下文的beanFactoryPostProcessors变量的值，并且实例化调用执行所有已经注册的beanFactoryPostProcessorPostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());// Detect a LoadTimeWeaver and prepare for weaving, if found in the meantime// (e.g. through an @Bean method registered by ConfigurationClassPostProcessor)if (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));}
}

getBeanFactoryPostProcessors()

默认情况下，通过此来获取已经注册的BFPP（BeanFactoryPostProcessor），但是默认是空的，此处也可以将自定义的BFPP获取到

自定义BFPP

实现BFPP接口

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor {@Overridepublic void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {System.out.println("自定义BeanFactoryPostProcessor");}
}

将自定义BFPP注入到IOC容器或者自定义ClassPathXmlApplicationContext重写在getBeanFactoryPostProcessors()调用之前的任意方法调用父类的addBeanFactoryPostProcessor()进行BFPP的注入，如：customizeBeanFactory()

import com.armin.self_bfpp.MyBeanFactoryPostProcessor;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class MyClassPathApplicationContext extends ClassPathXmlApplicationContext {public MyClassPathApplicationContext(String... configLocations) throws BeansException {super(configLocations);}@Overrideprotected void customizeBeanFactory(DefaultListableBeanFactory beanFactory) {super.addBeanFactoryPostProcessor(new MyBeanFactoryPostProcessor());super.customizeBeanFactory(beanFactory);}
}

PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors()

实例化调用执行所有已经注册的beanFactoryPostProcessor

public static void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {// Invoke BeanDefinitionRegistryPostProcessors first, if any.// 无论是什么情况，优先执行BeanDefinitionRegistryPostProcessors// 将已经执行过的BFPP存储在processedBeans中，防止重复执行Set<String> processedBeans = new HashSet<>();// 判断beanfactory是否是BeanDefinitionRegistry类型，此处是DefaultListableBeanFactory,实现了BeanDefinitionRegistry接口，所以为trueif (beanFactory instanceof BeanDefinitionRegistry) {// 类型转换BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;// 此处希望大家做一个区分，两个接口是不同的，BeanDefinitionRegistryPostProcessor是BeanFactoryPostProcessor的子集// BeanFactoryPostProcessor主要针对的操作对象是BeanFactory，而BeanDefinitionRegistryPostProcessor主要针对的操作对象是BeanDefinition// 存放BeanFactoryPostProcessor的集合List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();// 存放BeanDefinitionRegistryPostProcessor的集合List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();// 首先处理入参中的beanFactoryPostProcessors,遍历所有的beanFactoryPostProcessors，将BeanDefinitionRegistryPostProcessor// 和BeanFactoryPostProcessor区分开for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {// 如果是BeanDefinitionRegistryPostProcessorif (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {BeanDefinitionRegistryPostProcessor registryProcessor =(BeanDefinitionRegistryPostProcessor) postProcessor;// 直接执行BeanDefinitionRegistryPostProcessor接口中的postProcessBeanDefinitionRegistry方法registryProcessor.postProcessBeanDefinitionRegistry(registry);// 添加到registryProcessors，用于后续执行postProcessBeanFactory方法registryProcessors.add(registryProcessor);} else {// 否则，只是普通的BeanFactoryPostProcessor，添加到regularPostProcessors，用于后续执行postProcessBeanFactory方法regularPostProcessors.add(postProcessor);}}// Do not initialize FactoryBeans here: We need to leave all regular beans// uninitialized to let the bean factory post-processors apply to them!// Separate between BeanDefinitionRegistryPostProcessors that implement// PriorityOrdered, Ordered, and the rest.// 用于保存本次要执行的BeanDefinitionRegistryPostProcessorList<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.// 调用所有实现PriorityOrdered接口的BeanDefinitionRegistryPostProcessor实现类// 找到所有实现BeanDefinitionRegistryPostProcessor接口bean的beanNameString[] postProcessorNames =beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);// 遍历处理所有符合规则的postProcessorNamesfor (String ppName : postProcessorNames) {// 检测是否实现了PriorityOrdered接口if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {// 获取名字对应的bean实例，添加到currentRegistryProcessors中currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));// 将要被执行的BFPP名称添加到processedBeans，避免后续重复执行processedBeans.add(ppName);}}// 按照优先级进行排序操作sortPostProcessors(currentRegistryProcessors, beanFactory);// 添加到registryProcessors中，用于最后执行postProcessBeanFactory方法registryProcessors.addAll(currentRegistryProcessors);// 遍历currentRegistryProcessors，执行postProcessBeanDefinitionRegistry方法invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);// 执行完毕之后，清空currentRegistryProcessorscurrentRegistryProcessors.clear();// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.// 调用所有实现Ordered接口的BeanDefinitionRegistryPostProcessor实现类// 找到所有实现BeanDefinitionRegistryPostProcessor接口bean的beanName，// 此处需要重复查找的原因在于上面的执行过程中可能会新增其他的BeanDefinitionRegistryPostProcessorpostProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);for (String ppName : postProcessorNames) {// 检测是否实现了Ordered接口，并且还未执行过if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {// 获取名字对应的bean实例，添加到currentRegistryProcessors中currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));// 将要被执行的BFPP名称添加到processedBeans，避免后续重复执行processedBeans.add(ppName);}}// 按照优先级进行排序操作sortPostProcessors(currentRegistryProcessors, beanFactory);// 添加到registryProcessors中，用于最后执行postProcessBeanFactory方法registryProcessors.addAll(currentRegistryProcessors);// 遍历currentRegistryProcessors，执行postProcessBeanDefinitionRegistry方法invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);// 执行完毕之后，清空currentRegistryProcessorscurrentRegistryProcessors.clear();// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.// 最后，调用所有剩下的BeanDefinitionRegistryPostProcessorsboolean reiterate = true;while (reiterate) {reiterate = false;// 找出所有实现BeanDefinitionRegistryPostProcessor接口的类postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);// 遍历执行for (String ppName : postProcessorNames) {// 跳过已经执行过的BeanDefinitionRegistryPostProcessorif (!processedBeans.contains(ppName)) {// 获取名字对应的bean实例，添加到currentRegistryProcessors中currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));// 将要被执行的BFPP名称添加到processedBeans，避免后续重复执行processedBeans.add(ppName);reiterate = true;}}// 按照优先级进行排序操作sortPostProcessors(currentRegistryProcessors, beanFactory);// 添加到registryProcessors中，用于最后执行postProcessBeanFactory方法registryProcessors.addAll(currentRegistryProcessors);// 遍历currentRegistryProcessors，执行postProcessBeanDefinitionRegistry方法invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);// 执行完毕之后，清空currentRegistryProcessorscurrentRegistryProcessors.clear();}// Now, invoke the postProcessBeanFactory callback of all processors handled so far.// 调用所有BeanDefinitionRegistryPostProcessor的postProcessBeanFactory方法invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);// 最后，调用入参beanFactoryPostProcessors中的普通BeanFactoryPostProcessor的postProcessBeanFactory方法invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);} else {// Invoke factory processors registered with the context instance.// 如果beanFactory不归属于BeanDefinitionRegistry类型，那么直接执行postProcessBeanFactory方法invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);}// 到这里为止，入参beanFactoryPostProcessors和容器中的所有BeanDefinitionRegistryPostProcessor已经全部处理完毕，下面开始处理容器中// 所有的BeanFactoryPostProcessor// 可能会包含一些实现类，只实现了BeanFactoryPostProcessor，并没有实现BeanDefinitionRegistryPostProcessor接口// Do not initialize FactoryBeans here: We need to leave all regular beans// uninitialized to let the bean factory post-processors apply to them!// 找到所有实现BeanFactoryPostProcessor接口的类String[] postProcessorNames =beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,// Ordered, and the rest.// 用于存放实现了PriorityOrdered接口的BeanFactoryPostProcessorList<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();// 用于存放实现了Ordered接口的BeanFactoryPostProcessor的beanName//        List<String> orderedPostProcessorNames = new ArrayList<>();List<BeanFactoryPostProcessor> orderedPostProcessor = new ArrayList<>();// 用于存放普通BeanFactoryPostProcessor的beanName//       List<String> nonOrderedPostProcessorNames = new ArrayList<>();List<BeanFactoryPostProcessor> nonOrderedPostProcessorNames = new ArrayList<>();// 遍历postProcessorNames,将BeanFactoryPostProcessor按实现PriorityOrdered、实现Ordered接口、普通三种区分开for (String ppName : postProcessorNames) {// 跳过已经执行过的BeanFactoryPostProcessorif (processedBeans.contains(ppName)) {// skip - already processed in first phase above}// 添加实现了PriorityOrdered接口的BeanFactoryPostProcessor到priorityOrderedPostProcessorselse if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));}// 添加实现了Ordered接口的BeanFactoryPostProcessor的beanName到orderedPostProcessorNameselse if (beanFactory.isTypeMatch(ppName, Ordered.class)) {//              orderedPostProcessorNames.add(ppName);orderedPostProcessor.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));} else {// 添加剩下的普通BeanFactoryPostProcessor的beanName到nonOrderedPostProcessorNames//              nonOrderedPostProcessorNames.add(ppName);nonOrderedPostProcessorNames.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));}}// First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.// 对实现了PriorityOrdered接口的BeanFactoryPostProcessor进行排序sortPostProcessors(priorityOrderedPostProcessors, beanFactory);// 遍历实现了PriorityOrdered接口的BeanFactoryPostProcessor，执行postProcessBeanFactory方法invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);// Next, invoke the BeanFactoryPostProcessors that implement Ordered.// 创建存放实现了Ordered接口的BeanFactoryPostProcessor集合//        List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());// 遍历存放实现了Ordered接口的BeanFactoryPostProcessor名字的集合//       for (String postProcessorName : orderedPostProcessorNames) {// 将实现了Ordered接口的BeanFactoryPostProcessor添加到集合中//           orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));//        }// 对实现了Ordered接口的BeanFactoryPostProcessor进行排序操作//      sortPostProcessors(orderedPostProcessors, beanFactory);sortPostProcessors(orderedPostProcessor, beanFactory);// 遍历实现了Ordered接口的BeanFactoryPostProcessor，执行postProcessBeanFactory方法//     invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);invokeBeanFactoryPostProcessors(orderedPostProcessor, beanFactory);// Finally, invoke all other BeanFactoryPostProcessors.// 最后，创建存放普通的BeanFactoryPostProcessor的集合//     List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size());// 遍历存放实现了普通BeanFactoryPostProcessor名字的集合//     for (String postProcessorName : nonOrderedPostProcessorNames) {// 将普通的BeanFactoryPostProcessor添加到集合中//          nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));//     }// 遍历普通的BeanFactoryPostProcessor，执行postProcessBeanFactory方法//       invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);invokeBeanFactoryPostProcessors(nonOrderedPostProcessorNames, beanFactory);// Clear cached merged bean definitions since the post-processors might have// modified the original metadata, e.g. replacing placeholders in values...// 清除元数据缓存（mergeBeanDefinitions、allBeanNamesByType、singletonBeanNameByType）// 因为后置处理器可能已经修改了原始元数据，例如，替换值中的占位符beanFactory.clearMetadataCache();
}

整个方法的大致执行流程

首先执行beanFactory调用addBeanFactoryPostProcessor添加的BeanFactoryPostProcessor

如果该类为BeanDefinitionRegistryPostProcessor的实现先执行BeanDefinitionRegistryPostProcessor中的postProcessBeanDefinitionRegistry方法再将该实例放入集合中后续统一执行父接（BeanFactoryPostProcessor）口中的postProcessBeanFactory方法

从BeanFactory中获取BeanDefinitionRegistryPostProcessor并且实现PriorityOrdered接口的BeanName，然后通过BeanFactory中<T> T getBean(String name, Class<T> requiredType)方法获取实例（该方法会调用实例化Bean中的creatBean方法），放入集合先统一执行postProcessBeanDefinitionRegistry再将该对象放入另一个集合后续统一执行postProcessBeanFactory方法

再次重复第2点（不一样的地方：PriorityOrdered改为Ordered）

执行剩下的BeanDefinitionRegistryPostProcessor考虑可能存在执行上一步的时候在BeanDefinitionRegistryPostProcessor 对象中调用postProcessBeanDefinitionRegistry会添加新的BeanDefinitionRegistryPostProcessor 对象此处会循环将所有的BeanDefinitionRegistryPostProcessor 执行完

获取BeanFactoryPostProcessor类型的所有BeanName根据是否实现PriorityOrdered,Ordered和没有实现任何排序接口的依次从前往后执行postProcessBeanFactory方法

invokeBeanDefinitionRegistryPostProcessors()

调用给定BeanDefinitionRegistryPostProcessor Bean对象

private static void invokeBeanDefinitionRegistryPostProcessors(Collection<? extends BeanDefinitionRegistryPostProcessor> postProcessors, BeanDefinitionRegistry registry) {//遍历 postProcessorsfor (BeanDefinitionRegistryPostProcessor postProcessor : postProcessors) {//调用 postProcessor 的 postProcessBeanDefinitionRegistry以使得postProcess往registry注册BeanDefinition对象postProcessor.postProcessBeanDefinitionRegistry(registry);}
}

invokeBeanFactoryPostProcessors()

调用给定的BeanFactoryPostProcessor类型Bean对象

private static void invokeBeanFactoryPostProcessors(Collection<? extends BeanFactoryPostProcessor> postProcessors, ConfigurableListableBeanFactory beanFactory) {//遍历postProcessorsfor (BeanFactoryPostProcessor postProcessor : postProcessors) {//回调 BeanFactoryPostProcessor 的 postProcessBeanFactory 方法，使得每个postProcessor对象都可以对// beanFactory进行调整postProcessor.postProcessBeanFactory(beanFactory);}
}

测试从BeanFactory中根据类型获取到的BeanDefinitionRegisterPostProcessor在其中又添加新的BeanDefinitionRegisterPostProcessor执行结果

MyBeanDefinitionRegisterPostProcessor

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor;public class MyBeanDefinitionRegisterPostProcessor implements BeanDefinitionRegistryPostProcessor {@Overridepublic void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {System.out.println("执行postProcessBeanDefinitionRegistry()--" + getClass().getName());BeanDefinitionBuilder builder = BeanDefinitionBuilder.rootBeanDefinition(MySelfBeanDefinitionRegisterPostProcessor.class);builder.addPropertyValue("name", "armin");registry.registerBeanDefinition("mySelfBdrpp",builder.getBeanDefinition());}@Overridepublic void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {System.out.println("执行postProcessBeanFactory()--" + getClass().getName());}
}

MySelfBeanDefinitionRegisterPostProcessor

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor;public class MySelfBeanDefinitionRegisterPostProcessor implements BeanDefinitionRegistryPostProcessor {private String name;public String getName() {return name;}public void setName(String name) {this.name = name;}@Overridepublic void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {System.out.println("执行postProcessBeanDefinitionRegistry()--" + getClass().getName());}@Overridepublic void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {System.out.println("执行postProcessBeanFactory()--" + getClass().getName());}
}

Test

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;public class Test {public static void main(String[] args) {ApplicationContext ac = new ClassPathXmlApplicationContext("armin-self-bdrpp.xml");}}

armin-self-bdrpp.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"><bean class="com.armin.self_bdrpp.MyBeanDefinitionRegisterPostProcessor"></bean></beans>

执行结果

> Task :spring-debug:Test.main()
执行postProcessBeanDefinitionRegistry()--com.armin.self_bdrpp.MyBeanDefinitionRegisterPostProcessor
执行postProcessBeanDefinitionRegistry()--com.armin.self_bdrpp.MySelfBeanDefinitionRegisterPostProcessor
执行postProcessBeanFactory()--com.armin.self_bdrpp.MyBeanDefinitionRegisterPostProcessor
执行postProcessBeanFactory()--com.armin.self_bdrpp.MySelfBeanDefinitionRegisterPostProcessorBUILD SUCCESSFUL in 2m 1s