SpringBoot重新整理上下文一共七篇，基于SpringBoot 2.2.7.RELEASE，Spring 5.2.6.RELEASE
SpringBoot 重新整理上下文1–主流程
SpringBoot 重新整理上下文2–執行BeanDefinitionRegistryPostProcessor
SpringBoot 重新整理上下文3–解析引導類
SpringBoot 重新整理上下文4–處理ComponentScan
SpringBoot 重新整理上下文5–處理其他注解
SpringBoot 重新整理上下文6–加載并注冊BeanDefinition
SpringBoot 重新整理上下文7–執行BeanFactoryPostProcessor
SpringBoot重新整理上下文，在run方法裡面調refreshContext 方法。
//org.springframework.boot.SpringApplication#refreshContext
private void refreshContext(ConfigurableApplicationContext context) {
refresh(context);
if (this.registerShutdownHook) {
try {
context.registerShutdownHook();
}
catch (AccessControlException ex) {
// Not allowed in some environments.
}
}
}
調了本類的refresh
//org.springframework.boot.SpringApplication#refresh
protected void refresh(ApplicationContext applicationContext) {
Assert.isInstanceOf(AbstractApplicationContext.class, applicationContext);
//執行上下文的重新整理方法
((AbstractApplicationContext) applicationContext).refresh();
}
AbstractApplicationContext 的 refresh 方法。從這裡就進入了Spring的上下文。
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
...
// Tell the subclass to refresh the internal bean factory.
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
...
// Invoke factory processors registered as beans in the context.
invokeBeanFactoryPostProcessors(beanFactory);
...
}
}
這裡隻看 AbstractApplicationContext#refresh 中的兩個方法，obtainFreshBeanFactory 用來獲得BeanFactory，invokeBeanFactoryPostProcessors 用來初始化Spring的IOC。
1、獲得BeanFactory
//org.springframework.context.support.AbstractApplicationContext#obtainFreshBeanFactory
protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
refreshBeanFactory();
return getBeanFactory();
}
SpringBoot會根據環境建立三種上下文:
AnnotationConfigServletWebServerApplicationContext
AnnotationConfigReactiveWebServerApplicationContext
AnnotationConfigApplicationContext。
這三種上下文都繼承了 GenericApplicationContext ，GenericApplicationContext 繼承了 AbstractApplicationContext 。
1.1、重新整理BeanFactory
private final AtomicBoolean refreshed = new AtomicBoolean();
private final DefaultListableBeanFactory beanFactory;
//org.springframework.context.support.GenericApplicationContext#refreshBeanFactory
protected final void refreshBeanFactory() throws IllegalStateException {
if (!this.refreshed.compareAndSet(false, true)) {
throw new IllegalStateException(
"GenericApplicationContext does not support multiple refresh attempts: just call 'refresh' once");
}
this.beanFactory.setSerializationId(getId());
}
這個方法并沒有做什麼處理，不像 ClassPathXmlApplicationContext 那樣直接調用 AbstractRefreshableApplicationContext的 refreshBeanFactory 去 初始化ioc容器。
這裡調了BeanFactory，但是并沒有建立BeanFactory的邏輯。
建立BeanFactory的邏輯在構造器。
public GenericApplicationContext() {
this.beanFactory = new DefaultListableBeanFactory();
}
當建立上面三種上下文的時候，會執行父上下文 GenericApplicationContext 建立一個 DefaultListableBeanFactory 。
1.2、獲得BeanFactory
//org.springframework.context.support.GenericApplicationContext#getBeanFactory
public final ConfigurableListableBeanFactory getBeanFactory() {
return this.beanFactory;
}
2、初始化IOC
實際調用的是 AbstractApplicationContext#invokeBeanFactoryPostProcessors 方法，利用Spring的BeanFactory的後置處理器初始化IOC。
//org.springframework.context.support.AbstractApplicationContext#invokeBeanFactoryPostProcessors
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
//調用Spring的BeanFactory後知處理器。
PostProcessorRegistrationDelegate.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()));
}
}
調用BeanFactory的後置處理器
//org.springframework.context.support.PostProcessorRegistrationDelegate#invokeBeanFactoryPostProcessors(org.springframework.beans.factory.config.ConfigurableListableBeanFactory, java.util.List<org.springframework.beans.factory.config.BeanFactoryPostProcessor>)
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
// 儲存被處理過的bean的名稱。
Set<String> processedBeans = new HashSet<>();
//beanFactory 是 DefaultListableBeanFactory ，實作了 BeanDefinitionRegistry
if (beanFactory instanceof BeanDefinitionRegistry) {
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
//調用 BeanFactoryPostProcessor 的 postProcessBeanDefinitionRegistry
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
registryProcessor.postProcessBeanDefinitionRegistry(registry);
registryProcessors.add(registryProcessor);
}
else {
regularPostProcessors.add(postProcessor);
}
}
//走到這裡，registryProcessor 和 regularPostProcessors 分别是
//registryProcessors 0 = {SharedMetadataReaderFactoryContextInitializer$CachingMetadataReaderFactoryPostProcessor}
//1 = {ConfigurationWarningsApplicationContextInitializer$ConfigurationWarningsPostProcessor}
//regularPostProcessors 0 = {ConfigFileApplicationListener$PropertySourceOrderingPostProcessor}
//registryProcessor 中的兩個後知處理器執行了 postProcessBeanDefinitionRegistry 方法
// 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.
// 這裡将BeanDefinitionRegistryPostProcessor 按 PriorityOrdered, Ordered, 和其他 區分
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
// postProcessorNames = "org.springframework.context.annotation.internalConfigurationAnnotationProcessor"
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
//processedBeans = "org.springframework.context.annotation.internalConfigurationAnnotationProcessor"
//currentRegistryProcessors = ConfigurationClassPostProcessor
//排序
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
// 現在 registryProcessors = {[email protected]} size = 3
// 0 = {SharedMetadataReaderFactoryCon[email protected]}
// 1 = {ConfigurationWarningsApplica[email protected]}
// 2 = {[email protected]}
//調用 BeanDefinitionRegistryPostProcessors
// 這裡currentRegistryProcessors = ConfigurationClassPostProcessor
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
// currentRegistryProcessors 清空
currentRegistryProcessors.clear();
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
// 下面這一段調用 實作了 order 的 BeanDefinitionRegistryPostProcessors
// postProcessorNames = "org.springframework.context.annotation.internalConfigurationAnnotationProcessor"
postProcessorNames = 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);
}
}
// processedBeans = 0 = "org.springframework.context.annotation.internalConfigurationAnnotationProcessor"
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
// 現在 registryProcessors = {[email protected]} size = 3
// 0 = {SharedMetadataReaderFactoryCon[email protected]}
// 1 = {ConfigurationWarningsApplica[email protected]}
// 2 = {[email protected]}
//currentRegistryProcessors 為空
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
// 調用所有其他的 BeanDefinitionRegistryPostProcessors
// 這個循環裡面沒有任何操作。。。
boolean reiterate = true;
while (reiterate) {
reiterate = false;
//org.springframework.context.annotation.internalConfigurationAnnotationProcessor
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
// 這裡是false
if (!processedBeans.contains(ppName)) {
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
reiterate = true;
}
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
// currentRegistryProcessors 為空
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
}
// Now, invoke the postProcessBeanFactory callback of all processors handled so far.
// 調用所有 postProcessBeanFactory
// registryProcessors = org.springframework.boot.autoconfigure.SharedMetadataReaderFactoryContextInitializer.CachingMetadataReaderFactoryPostProcessor,org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer.ConfigurationWarningsPostProcessor,org.springframework.context.annotation.ConfigurationClassPostProcessor
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
//regularPostProcessors = org.springframework.boot.context.config.ConfigFileApplicationListener.PropertySourceOrderingPostProcessor
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
}
else {
// Invoke factory processors registered with the context instance.
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
}
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let the bean factory post-processors apply to them!
// 不初始化FactoryBeans 下面是 BeanFactoryPostProcessor
//0 = "org.springframework.context.annotation.internalConfigurationAnnotationProcessor"
//1 = "org.springframework.context.event.internalEventListenerProcessor"
//2 = "propertySourcesPlaceholderConfigurer"
//3 = "org.springframework.boot.context.properties.ConfigurationPropertiesBeanDefinitionValidator"
//4 = "preserveErrorControllerTargetClassPostProcessor"
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
// Ordered, and the rest.
//按 order 分為三個集合，優先級order，普通order，沒有order
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);
//調用 實作優先級order 的 bean 的
// priorityOrderedPostProcessors = {[email protected]}
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);
//調用 實作普通order 的 bean 的
// orderedPostProcessors = {ConfigurationPropertiesBeanDefinitionValidator}
invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
// Finally, invoke all other BeanFactoryPostProcessors.
// 調用其他 BeanFactoryPostProcessors
List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size());
for (String postProcessorName : nonOrderedPostProcessorNames) {
nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
//調用 沒有實作order 的 bean 的
//nonOrderedPostProcessors = 0 = {[email protected]}
// 1 = {ErrorMvcAutoConf[email protected]}
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();
}
上面這個大方法主要做了兩件事，調用所有 BeanDefinitionRegistryPostProcessor 和 BeanFactoryPostProcessor 。
對于注解的掃描和處理，加載，注冊，都在 org.springframework.context.annotation.ConfigurationClassPostProcessor#postProcessBeanDefinitionRegistry中。
其中BeanDefinitionRegistryPostProcessor 的有：
org.springframework.boot.autoconfigure.SharedMetadataReaderFactoryContextInitializer.CachingMetadataReaderFactoryPostProcessor,
org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer.ConfigurationWarningsPostProcessor,
org.springframework.context.annotation.ConfigurationClassPostProcessor
BeanFactoryPostProcessor 的有：
org.springframework.boot.autoconfigure.SharedMetadataReaderFactoryContextInitializer.CachingMetadataReaderFactoryPostProcessor,
org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer.ConfigurationWarningsPostProcessor,
org.springframework.context.annotation.ConfigurationClassPostProcessor
org.springframework.boot.context.config.ConfigFileApplicationListener.PropertySourceOrderingPostProcessor
org.springframework.context.support.PropertySourcesPlaceholderConfigurer
org.springframework.boot.context.properties.ConfigurationPropertiesBeanDefinitionValidator
org.springframework.context.event.EventListenerMethodProcessor
org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration$PreserveErrorControllerTargetClassPostProcessor
按照 order 分為
priorityOrderedPostProcessors = PropertySourcesPlaceholderConfigurer
orderedPostProcessors = ConfigurationPropertiesBeanDefinitionValidator
nonOrderedPostProcessors = EventListenerMethodProcessor，ErrorMvcAutoConfiguration$PreserveErrorControllerTargetClassPostProcessor
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