Spring源码 11 IOC refresh方法6
Spring IOC 的核心是
AbstractApplicationContext
的refresh
方法。
其中一共有 13 个主要方法,这里分析第 6 个:registerBeanPostProcessors
。
1 AbstractApplicationContext
1-1 注册 Bean 增强器
registerBeanPostProcessors(beanFactory)
protected void registerBeanPostProcessors(ConfigurableListableBeanFactory beanFactory) {
// 注册 Bean 增强器
PostProcessorRegistrationDelegate.registerBeanPostProcessors(beanFactory, this);
}
1-2 注册 Bean 增强器
PostProcessorRegistrationDelegate.registerBeanPostProcessors(beanFactory, this)
2 PostProcessorRegistrationDelegate
public static void registerBeanPostProcessors(ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);
/**
* BeanPostProcessorChecker 是一个普通的信息打印,可能会有些情况
* 当 Spring 的配置中的后处理器还没有被注册就已经开始了 bean 的初始化时
* 便会打印出 BeanPostProcessorChecker 中设定的信息
*/
int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
// 使用 PriorityOrdered 保证顺序
List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();
// 使用 Ordered 保证顺序
List<String> orderedPostProcessorNames = new ArrayList<>();
// 无序 BeanPostProcessor
List<String> nonOrderedPostProcessorNames = new ArrayList<>();
for (String ppName : postProcessorNames) {
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
priorityOrderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
} else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
orderedPostProcessorNames.add(ppName);
} else {
nonOrderedPostProcessorNames.add(ppName);
}
}
// 第 1 步,排序增强器。注册所有实现 PriorityOrdered 的 BeanPostProcessor
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
// 注册 Bean 增强器
registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
// 第 2 步,注册所有实现 Ordered 的 BeanPostProcessor
List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());
for (String ppName : orderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
orderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
sortPostProcessors(orderedPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, orderedPostProcessors);
// 第 3 步,注册所有无序的 BeanPostProcessor
List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size());
for (String ppName : nonOrderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
nonOrderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
/**
* 第 4 步,注册所有 MergedBeanDefinitionPostProcessor 类型的 BeanPostProcessor,并非重复注册
* 在 beanFactory.addBeanPostProcessor 中会先移除已经存在的 BeanPostProcessor
*/
sortPostProcessors(internalPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, internalPostProcessors);
// 添加 ApplicationListener 探测器
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
}
2-1 排序增强器
sortPostProcessors(priorityOrderedPostProcessors, beanFactory)
private static void sortPostProcessors(List<?> postProcessors, ConfigurableListableBeanFactory beanFactory) {
if (postProcessors.size() <= 1) {
return;
}
Comparator<Object> comparatorToUse = null;
if (beanFactory instanceof DefaultListableBeanFactory) {
comparatorToUse = ((DefaultListableBeanFactory) beanFactory).getDependencyComparator();
}
if (comparatorToUse == null) {
comparatorToUse = OrderComparator.INSTANCE;
}
postProcessors.sort(comparatorToUse);
}
2-2 注册 Bean 增强器
registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors)
private static void registerBeanPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanPostProcessor> postProcessors) {
if (beanFactory instanceof AbstractBeanFactory) {
// Bulk addition is more efficient against our CopyOnWriteArrayList there
((AbstractBeanFactory) beanFactory).addBeanPostProcessors(postProcessors);
}
else {
for (BeanPostProcessor postProcessor : postProcessors) {
beanFactory.addBeanPostProcessor(postProcessor);
}
}
}
参考
https://www.bilibili.com/video/BV1tR4y1F75R?spm_id_from=333.337.search-card.all.click
https://www.bilibili.com/video/BV12Z4y197MU?spm_id_from=333.999.0.0
《Spring源码深度解析(第2版)》
版本
Spring 5.3.15
天河有尽身作涯,星海无边前是岸。