花了幾篇文章 探究Spring的 BeanPostProcessor
和BeanFactoryPostProcessor
,本文則開始接受refresh
後續邏輯。
registerBeanPostProcessors
registerBeanPostProcessors
方法主要是調用所有BeanPostProcess
的自帶方法:
public static void registerBeanPostProcessors(
ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
// 獲取所有的 BeanPostProcessor
String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);
// 記錄信息,即當前beanFactory有幾個beanpostProcessor,而最終要有多少個。
// +1 的原因是加上 BeanPostProcessorChecker 類型BeanPostProcessor
int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
// BeanPostProcessorChecker 主要是檢查數量
beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
// 將實現PriorityOrdered的接口放入priorityOrderedPostProcessors中,Ordered 放入 orderedPostProcessorNames,其他放入 nonOrderedPostProcessorNames中。
// 另外,如果既是PriorityOrdered又是MergedBeanDefinitionPostProcessor,則放入internalPostProcessors
List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();
List<String> orderedPostProcessorNames = new ArrayList<>();
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);
}
}
// 將所有 priorityOrderedPostProcessors 注入beanFacotory.
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
// 將所有orderedPostProcessors 注入beanFactory,並將MergedBeanDefinitionPostProcessor 放入internalPostProcessors 中.
List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>();
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);
// 將所有其他的 nonOrderedPostProcessors 注入beanFactory,並將MergedBeanDefinitionPostProcessor 放入internalPostProcessors 中.
List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<>();
for (String ppName : nonOrderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
nonOrderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
// 重新再將 internalPostProcessors 注入beanFactory中.
sortPostProcessors(internalPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, internalPostProcessors);
// 添加 ApplicationListenerDetector 到beanFactory中Re-register post-processor for detecting inner beans as ApplicationListeners,
// moving it to the end of the processor chain (for picking up proxies etc).
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
}
上面邏輯主要是區分 不同類型的 BeanPostProcessors,並按照 PriorityOrdered
-> Ordered
-> 其他
順序放入beanFactory中。
而最後,將 MergedBeanDefinitionPostProcessor
類型節點,重新放到後面。而將 ApplicationListenerDetector
則用於永遠放到最後一個。
ApplicationListenerDetector
主要是將 屬於 ApplicationListener
類型bean註冊進 ApplicationEventMulticaster
,以便全局事件通知。
initMessageSource
初始化一個MessageSource
,主要用於 國際化i18n。如果沒有在beanFactory中配置 messageSource
的bean,則會創建一個空的messageSource
的 DelegatingMessageSource
進行處理。
initApplicationEventMulticaster
初始化 消息廣播器,如果當前beanFactory中沒有,同樣會創建一個默認的 ApplicationEventMulticaster
的 SimpleApplicationEventMulticaster
。
並配置金beanFactory:
protected void initApplicationEventMulticaster() {
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {
this.applicationEventMulticaster =
beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);
if (logger.isTraceEnabled()) {
logger.trace("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");
}
}
else {
this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);
if (logger.isTraceEnabled()) {
logger.trace("No '" + APPLICATION_EVENT_MULTICASTER_BEAN_NAME + "' bean, using " +
"[" + this.applicationEventMulticaster.getClass().getSimpleName() + "]");
}
}
}
onRefresh
可以用來做一些特殊的refresh工作,例如提前初始化一些特殊的bean等。
registerListeners
將實現了 ApplicationListener
接口的bean註冊進消息廣播中ApplicationEventMulticaster
,這樣一旦有消息,就可以分發到每個對應的 ApplicationListener
類型的bean中。
protected void registerListeners() {
// Register statically specified listeners first.
for (ApplicationListener<?> listener : getApplicationListeners()) {
// 通過 applicationContext.addApplicationListeners 的bean
// 將所有的 ApplicationListener 類型bean註冊進ApplicationEventMulticaster
getApplicationEventMulticaster().addApplicationListener(listener);
}
// 將所有 實現了 ApplicationListener bean放入 applicationListnerBean中。
String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
for (String listenerBeanName : listenerBeanNames) {
getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
}
// 由於已經註冊了ApplicationListener,所以如果有 啓動階段發送的消息,那麼此時就可以發送
Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
this.earlyApplicationEvents = null;
if (earlyEventsToProcess != null) {
for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
getApplicationEventMulticaster().multicastEvent(earlyEvent);
}
}
}
finishBeanFactoryInitialization
在這裏面,beanFactory的初始化將進入尾聲,則裏面,Spring會對所有bean調用getBean的初始化方法。
protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
// 設置特定的類型轉化bean
if (beanFactory.containsBean(CONVERSION_SERVICE_BEAN_NAME) &&
beanFactory.isTypeMatch(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class)) {
beanFactory.setConversionService(
beanFactory.getBean(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class));
}
// 如果沒有配置值解析器,則會使用默認的值解析器。
if (!beanFactory.hasEmbeddedValueResolver()) {
beanFactory.addEmbeddedValueResolver(strVal -> getEnvironment().resolvePlaceholders(strVal));
}
// 初始化 代碼織入類,即 字節碼工具類 LoadTimeWeaverAware
String[] weaverAwareNames = beanFactory.getBeanNamesForType(LoadTimeWeaverAware.class, false, false);
for (String weaverAwareName : weaverAwareNames) {
getBean(weaverAwareName);
}
// Stop using the temporary ClassLoader for type matching.
beanFactory.setTempClassLoader(null);
// 保存所有bean實例快照
beanFactory.freezeConfiguration();
// 實例化所有bean,除了lazy屬性外。並調用所有 SmartInitializingSingleton 的afterSingletonsInstantiated 方法。
beanFactory.preInstantiateSingletons();
}
finishRefresh
做一些refresh尾聲工作,包括清楚緩存,全局發事件消息等。
protected void finishRefresh() {
// 清楚相關緩存
clearResourceCaches();
// 如果沒有 LifecycleProcessor 類型bean,則初始化一個默認的 DefaultLifecycleProcessor bean
initLifecycleProcessor();
// 調用 上一步LifecycleProcessor 的refresh方法。
getLifecycleProcessor().onRefresh();
// 全局發佈消息。
publishEvent(new ContextRefreshedEvent(this));
// 將當前ApplicationContext放入 LiveBeansView中。
LiveBeansView.registerApplicationContext(this);
}
- 清除相關緩存
- 如果沒有 LifecycleProcessor 類型bean,則初始化一個默認的 DefaultLifecycleProcessor bean
- 調用 上一步LifecycleProcessor 的refresh方法。
- 全局發佈消息。
- 將當前ApplicationContext放入 LiveBeansView中。
SpringContext設計爲支持多個容器,所以在LiveBeansView
中會有 靜態類型的ConfigurableApplicationContext
保存容器。
最後在finnaly塊中調用 resetCommonCaches
清除一些用到的緩存,釋放佔用內存。