Spring - 手把手分析 IoC 容器创建过程

概述

这里我们以 Spring 5.2.8.RELEASE 版本为例，看一下 IoC 容器 的创建过程。同时我们使用 java-based 的方式实例化 IoC 容器，即使用 AnnotationConfigApplicationContext + @Configuration 的方式配置容器需要的组件。

ApplicationContext ctx = new AnnotationConfigApplicationContext(AppConfig.class);

查看 AnnotationConfigApplicationContext 的继承关系，可以看到这个继承关系还是很复杂的，其中重要的接口有 BeanFactory、ApplicationContext、ResourceLoader、BeanDefinitionRegistry、AnntationConfigRegistry 等：

public class AnnotationConfigApplicationContext extends GenericApplicationContext implements AnnotationConfigRegistry {
	...
}

查看创建 IoC 容器 所使用的 AnnotationConfigApplicationContext 的构造函数：

public AnnotationConfigApplicationContext(Class<?>... componentClasses) {
	// 1、初始化 IoC 容器和一些底层 Bean
	this();
	// 2、注册配置类到容器中
	register(componentClasses);
	// 3、核心流程
	refresh();
}

1、首先查看 this() 方法，即无参构造：

这里有一个细节就是如果你了解 Java 的 类初始化顺序 和 实例初始化顺序 的话，你会知道这里首先会初始化父类，不明白的可以先看一下Java - 详细分析 【类初始化】 和 【实例初始化】 的过程及顺序 这篇文章

首先执行父类 GenericApplicationContext 的初始化方法：

public GenericApplicationContext() {
	// 初始化了 BeanFactory
	this.beanFactory = new DefaultListableBeanFactory();
}

接着执行了自己的初始化方法：

再一次感叹 Spring 的命名，用词很准确、很严谨，基本上都可以做到见名知意，我们在开发中的命名也要尽量做到见名知意

public class AnnotationConfigApplicationContext extends GenericApplicationContext implements AnnotationConfigRegistry {

	private final AnnotatedBeanDefinitionReader reader;

	private final ClassPathBeanDefinitionScanner scanner;

	public AnnotationConfigApplicationContext() {
		// 1、注解形式的 BeanDefinition 读取器，用来识别 @Autowired、@Resource 等注解
		this.reader = new AnnotatedBeanDefinitionReader(this);
		// 2、用来扫描类路径下的 BeanDefinition
		this.scanner = new ClassPathBeanDefinitionScanner(this);
	}
	
	...
}

1.1、查看 AnnotatedBeanDefinitionReader 的构造函数：

// 这里的 registry 是 AnnotationConfigApplicationContext
public AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry) {
	this(registry, getOrCreateEnvironment(registry));
}

public AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry, Environment environment) {
	Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
	Assert.notNull(environment, "Environment must not be null");
	this.registry = registry;
	this.conditionEvaluator = new ConditionEvaluator(registry, environment, null);
	// 核心流程
	AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
}

接着查看 AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry) 源码：

public static void registerAnnotationConfigProcessors(BeanDefinitionRegistry registry) {
	registerAnnotationConfigProcessors(registry, null);
}

public static Set<BeanDefinitionHolder> registerAnnotationConfigProcessors(
			BeanDefinitionRegistry registry, @Nullable Object source) {
	// 首先获取到 DefaultListableBeanFactory，其实就是 IoC 容器
	DefaultListableBeanFactory beanFactory = unwrapDefaultListableBeanFactory(registry);
	...

	// 这里初始化一些底层的 BeanDefinition，比如处理 @Autowired、@Resource 注解的底层 Bean
	// 默认会初始化 5 个
	//org.springframework.context.annotation.internalConfigurationAnnotationProcessor
	//org.springframework.context.annotation.internalAutowiredAnnotationProcessor
	//org.springframework.context.annotation.internalCommonAnnotationProcessor
	//org.springframework.context.event.internalEventListenerProcessor
	//org.springframework.context.event.internalEventListenerFactory
	Set<BeanDefinitionHolder> beanDefs = new LinkedHashSet<>(8);

	...

	return beanDefs;
}

1.2、查看 ClassPathBeanDefinitionScanner 的构造函数

public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry) {
	this(registry, true);
}

public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters,
			Environment environment, @Nullable ResourceLoader resourceLoader) {

	Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
	this.registry = registry;

	if (useDefaultFilters) {
		// 1、注册默认的过滤器
		registerDefaultFilters();
	}
	// 2、设置 environment
	setEnvironment(environment);
	// 3、初始化 resourceLoader
	setResourceLoader(resourceLoader);
}

1.2.1、查看 registerDefaultFilters() 方法，主要是为了过滤 @Component、@ManagedBean、@Named 注解：

protected void registerDefaultFilters() {
	this.includeFilters.add(new AnnotationTypeFilter(Component.class));
	ClassLoader cl = ClassPathScanningCandidateComponentProvider.class.getClassLoader();
	try {
		this.includeFilters.add(new AnnotationTypeFilter(
				((Class<? extends Annotation>) ClassUtils.forName("javax.annotation.ManagedBean", cl)), false));
		...
	try {
		this.includeFilters.add(new AnnotationTypeFilter(
				((Class<? extends Annotation>) ClassUtils.forName("javax.inject.Named", cl)), false));
	...
}

1.2.2、设置 environment 信息

// 这里的 BeanDefinitionRegistry 为 AnnotationConfigApplicationContext
private static Environment getOrCreateEnvironment(BeanDefinitionRegistry registry) {
	Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
	// 从最上面的 AnnotationConfigApplicationContext 类图中可以看到这里为 true
	if (registry instanceof EnvironmentCapable) {
		// 这里会进入到 AnnotationConfigApplicationContext 的父类 AbstractApplicationContext 中的实现方法
		return ((EnvironmentCapable) registry).getEnvironment();
	}
	return new StandardEnvironment();
}

// AbstractApplicationContext

@Override
public ConfigurableEnvironment getEnvironment() {
	if (this.environment == null) {
		this.environment = createEnvironment();
	}
	return this.environment;
}

protected ConfigurableEnvironment createEnvironment() {
	return new StandardEnvironment();
}

2、查看 register(componentClasses)，注册配置类信息

由此可知，配置类也会作为一个 Bean 被注册到容器中

@Override
public void register(Class<?>... componentClasses) {
	Assert.notEmpty(componentClasses, "At least one component class must be specified");
	// 这里的 reader 就是上一步初始化的 AnnotatedBeanDefinitionReader
	this.reader.register(componentClasses);
}

// 重载方法
public void registerBean(Class<?> beanClass) {
	doRegisterBean(beanClass, null, null, null, null);
}

查看 AnnotatedBeanDefinitionReader 的 register 方法：

private <T> void doRegisterBean(Class<T> beanClass, @Nullable String name,
			@Nullable Class<? extends Annotation>[] qualifiers, @Nullable Supplier<T> supplier,
			@Nullable BeanDefinitionCustomizer[] customizers) {

	AnnotatedGenericBeanDefinition abd = new AnnotatedGenericBeanDefinition(beanClass);
	if (this.conditionEvaluator.shouldSkip(abd.getMetadata())) {
		return;
	}

	abd.setInstanceSupplier(supplier);
	// 处理 Bean 上面是否有 @Scope 注解
	ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(abd);
	abd.setScope(scopeMetadata.getScopeName());
	String beanName = (name != null ? name : this.beanNameGenerator.generateBeanName(abd, this.registry));

	// 处理其他注解，比如 @Lazy、@Primary、@DependsOn 等
	AnnotationConfigUtils.processCommonDefinitionAnnotations(abd);
	...

	BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(abd, beanName);
	definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
	// 注册 BeanDefinition
	BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, this.registry);
}

查看 BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, this.registry) 方法：

public static void registerBeanDefinition(
			BeanDefinitionHolder definitionHolder, BeanDefinitionRegistry registry)
			throws BeanDefinitionStoreException {

	// Register bean definition under primary name.
	String beanName = definitionHolder.getBeanName();
	// 注册 BeanDefinition 到 BeanFactory
	registry.registerBeanDefinition(beanName, definitionHolder.getBeanDefinition());

	// Register aliases for bean name, if any.
	String[] aliases = definitionHolder.getAliases();
	if (aliases != null) {
		for (String alias : aliases) {
			registry.registerAlias(beanName, alias);
		}
	}
}

这里使用的 registerBeanDefinition 方法是在 GenericApplicationContext 中重写的方法：

@Override
public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition)
		throws BeanDefinitionStoreException {
	// 这个 beanFacory 就是 this() 方法中初始化的 DefaultListableBeanFactory
	this.beanFactory.registerBeanDefinition(beanName, beanDefinition);
}

3、接下来就是最重要的 refresh() 方法

@Override
public void refresh() throws BeansException, IllegalStateException {
	synchronized (this.startupShutdownMonitor) {
		// Prepare this context for refreshing.
		// 1、做一些 refresh 前的准备工作
		prepareRefresh();

		// Tell the subclass to refresh the internal bean factory.
		// 2、让子类刷新内部 Bean 工厂
		ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

		// Prepare the bean factory for use in this context.
		// 3、BeanFactory 的一些准备工作，上一步并没有做太多，只是获取到了 BeanFactory
		prepareBeanFactory(beanFactory);

		try {
			// Allows post-processing of the bean factory in context subclasses.
			// 4、BeanFactory 准备工作完成后进行的后置处理
			postProcessBeanFactory(beanFactory);

			// Invoke factory processors registered as beans in the context.
			// 5、执行 BeanFactoryProcessor
			invokeBeanFactoryPostProcessors(beanFactory);

			// Register bean processors that intercept bean creation.
			// 6、注册 BeanPostProcessor
			registerBeanPostProcessors(beanFactory);

			// Initialize message source for this context.
			// 7、初始化MessageSource
			initMessageSource();

			// Initialize event multicaster for this context.
			// 8、初始化事件派发器
			initApplicationEventMulticaster();

			// Initialize other special beans in specific context subclasses.
			// 9、添加一些额外的 refresh 工作
			onRefresh();

			// Check for listener beans and register them.
			// 10、注册监听器
			registerListeners();

			// Instantiate all remaining (non-lazy-init) singletons.
			// 11、完成 BeanFactory 的初始化
			finishBeanFactoryInitialization(beanFactory);

			// Last step: publish corresponding event.
			// 12、完成 refresh 方法
			finishRefresh();
		}

		catch (BeansException ex) {
			...
		}

		finally {
			// Reset common introspection caches in Spring's core, since we
			// might not ever need metadata for singleton beans anymore...
			resetCommonCaches();
		}
	}
}

3.1、prepareRefresh() 刷新前的准备工作

protected void prepareRefresh() {
	// Switch to active.
	// 记录 Ioc 容器初始化开始时间戳，并设置当前状态是 close 还是 active
	this.startupDate = System.currentTimeMillis();
	this.closed.set(false);
	this.active.set(true);

	...

	// Initialize any placeholder property sources in the context environment.
	// 由子类实现，加载 PropertySource 到 context 环境中
	initPropertySources();

	// Validate that all properties marked as required are resolvable:
	// see ConfigurablePropertyResolver#setRequiredProperties
	// 校验属性是否合法等
	getEnvironment().validateRequiredProperties();

	// 保存一些 refresh 之前的 Listener 和 Event
	...
}

3.2、obtainFreshBeanFactory() 刷新并返回 BeanFactory

这两个方法都是抽象方法，又因为 AnnotationConfigApplicationContext 继承了 GenericApplicationContext，所以调用的是 GenericApplicationContext 中的 refreshBeanFactory 方法

protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
	// 核心流程，刷新 BeanFactory
	refreshBeanFactory();
	// 返回刷新后的 BeanFactory
	return getBeanFactory();
}

protected abstract void refreshBeanFactory() throws BeansException, IllegalStateException;

@Override
public abstract ConfigurableListableBeanFactory getBeanFactory() throws IllegalStateException;

查看 GenericApplicationContext 中的实现：

@Override
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");
	}
	// 只是设置了一下 serializationId
	this.beanFactory.setSerializationId(getId());
}

getBeanFactory() 方法返回的是第 1 步中初始化的 DefaultListableBeanFactory。

3.3、prepareBeanFactory(beanFactory) 进行一些属性设置

设置了很多属性，但是这里与主流程无关，就没有详细说明每一项属性的含义，感兴趣的可以查看官方文档。其实代码中的注释已经说的很清楚了，Spring 的撰写文档能力毋庸置疑，英语要学好啊。

protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
	// Tell the internal bean factory to use the context's class loader etc.
	// 设置类加载器
	beanFactory.setBeanClassLoader(getClassLoader());
	// 表达式解析器
	beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
	beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));

	// Configure the bean factory with context callbacks.
	// 添加一个 BeanPostProcessor：ApplicationContextAwareProcessor
	beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
	// 忽略各种 Aware
	beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
	beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);
	beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
	beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
	beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
	beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);

	// BeanFactory interface not registered as resolvable type in a plain factory.
	// MessageSource registered (and found for autowiring) as a bean.
	// 注册可识别的依赖，使我们可以在任何组件中自动注入
	beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
	beanFactory.registerResolvableDependency(ResourceLoader.class, this);
	beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
	beanFactory.registerResolvableDependency(ApplicationContext.class, this);

	// Register early post-processor for detecting inner beans as ApplicationListeners.
	beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));

	// Detect a LoadTimeWeaver and prepare for weaving, if found.
	if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
		beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
		// Set a temporary ClassLoader for type matching.
		beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
	}

	// Register default environment beans.
	// 注册了一些默认的 bean
	if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {
		beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());
	}
	if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) {
		beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties());
	}
	if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) {
		beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment());
	}
}

3.4、postProcessBeanFactory(beanFactory)

BeanFactory 准备工作完成后进行的后置处理工作，由子类重写这个方法来自定义具体的逻辑

protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
}

以上步骤主要完成了 BeanFactory 的创建以及预准备工作

---

3.5、invokeBeanFactoryPostProcessors(beanFactory)

执行 BeanFactoryPostProcessor，执行时机是在 BeanFactory 的标准初始化之后，所有的 BeanDefinition 已经被加载，但是还没有 Bean 被初始化。

protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
	// 核心流程
	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()));
	}
}

BeanFactoryPostProcessor 有一个子类 BeanDefinitionRegistryPostProcessor，在 PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors() 方法中，优先执行实现了 BeanDefinitionRegistryPostProcessor 的实现类，再执行实现了 BeanFactoryPostProcessor 的实现类，在 Spring - IoC 容器之拓展点 BeanFactoryPostProcessor 这篇文章中，有分析过，这里就不再赘述了。

3.6、registerBeanPostProcessors(beanFactory)

protected void registerBeanPostProcessors(ConfigurableListableBeanFactory beanFactory) {
	PostProcessorRegistrationDelegate.registerBeanPostProcessors(beanFactory, this);
}

public static void registerBeanPostProcessors(
			ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {

	String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);

	// Register BeanPostProcessorChecker that logs an info message when
	// a bean is created during BeanPostProcessor instantiation, i.e. when
	// a bean is not eligible for getting processed by all BeanPostProcessors.
	int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
	beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));

	// Separate between BeanPostProcessors that implement PriorityOrdered,
	// Ordered, and the rest.
	List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
	List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();
	List<String> orderedPostProcessorNames = new ArrayList<>();
	List<String> nonOrderedPostProcessorNames = new ArrayList<>();
	...

	// First, register the BeanPostProcessors that implement PriorityOrdered.
	sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
	registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);

	// Next, register the BeanPostProcessors that implement Ordered.
	List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());
	...
	sortPostProcessors(orderedPostProcessors, beanFactory);
	registerBeanPostProcessors(beanFactory, orderedPostProcessors);

	// Now, register all regular BeanPostProcessors.
	List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size());
	...
	registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);

	// Finally, re-register all internal BeanPostProcessors.
	sortPostProcessors(internalPostProcessors, beanFactory);
	registerBeanPostProcessors(beanFactory, internalPostProcessors);

	// 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));
}

首先获取到实现了 PriorityOrdered 的 BeanPostProcessor 并注册到 BeanFactory 中，其次获取实现了 Ordered 接口的并注册，之后注册没有排序规则的，最后注册实现了 MergedBeanDefinitionPostProcessor 接口的。

3.7、initMessageSource()

用来做国际化、消息处理、消息解析等功能，SpringMVC 中再详细分析这一块的源码

3.8、initApplicationEventMulticaster()

protected void initApplicationEventMulticaster() {
	ConfigurableListableBeanFactory beanFactory = getBeanFactory();
	if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {
		...
	}
	else {
		this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
		// 将 applicationEventMulticaster 添加到 IoC 容器中，以便其他组件可以引用
		beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);
		...
	}
}

3.9、onRefresh()

由子类实现自定义的逻辑，是为了添加一些特殊的 refresh 工作，比如：初始化一些特殊的 Bean

protected void onRefresh() throws BeansException {
	// For subclasses: do nothing by default.
}

3.10、registerListeners()

注册实现了 ApplicationListener 的监听器

protected void registerListeners() {
	// Register statically specified listeners first.
	for (ApplicationListener<?> listener : getApplicationListeners()) {
		getApplicationEventMulticaster().addApplicationListener(listener);
	}

	// Do not initialize FactoryBeans here: We need to leave all regular beans
	// uninitialized to let post-processors apply to them!
	String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
	for (String listenerBeanName : listenerBeanNames) {
		getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
	}

	// Publish early application events now that we finally have a multicaster...
	Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
	this.earlyApplicationEvents = null;
	if (!CollectionUtils.isEmpty(earlyEventsToProcess)) {
		for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
			getApplicationEventMulticaster().multicastEvent(earlyEvent);
		}
	}
}

3.11、【重要】finishBeanFactoryInitialization(beanFactory)

protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
	// 非核心流程这里就省略了
	...

	// Instantiate all remaining (non-lazy-init) singletons.
	beanFactory.preInstantiateSingletons();
}

在前面的流程中，有一些 Bean 已经被初始化，这里的 preInstantiateSingletons() 是用来初始化剩下的单实例 Bean，这里的 getBean(beanName) 就是创建 Bean 的过程，由于篇幅过长这里就不分析了，在 Spring - 分析 IoC 容器中 Bean 的创建过程 这篇文章中详细分析。

@Override
public void preInstantiateSingletons() throws BeansException {
	...

	// Iterate over a copy to allow for init methods which in turn register new bean definitions.
	// While this may not be part of the regular factory bootstrap, it does otherwise work fine.
	List<String> beanNames = new ArrayList<>(this.beanDefinitionNames);

	// Trigger initialization of all non-lazy singleton beans...
	for (String beanName : beanNames) {
		RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
		if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
			if (isFactoryBean(beanName)) {
				Object bean = getBean(FACTORY_BEAN_PREFIX + beanName);
				if (bean instanceof FactoryBean) {
					FactoryBean<?> factory = (FactoryBean<?>) bean;
					boolean isEagerInit;
					if (System.getSecurityManager() != null && factory instanceof SmartFactoryBean) {
						isEagerInit = AccessController.doPrivileged(
								(PrivilegedAction<Boolean>) ((SmartFactoryBean<?>) factory)::isEagerInit,
								getAccessControlContext());
					}
					else {
						isEagerInit = (factory instanceof SmartFactoryBean &&
								((SmartFactoryBean<?>) factory).isEagerInit());
					}
					if (isEagerInit) {
						getBean(beanName);
					}
				}
			}
			else {
				// 核心流程
				getBean(beanName);
			}
		}
	}

	// Trigger post-initialization callback for all applicable beans...
	for (String beanName : beanNames) {
		Object singletonInstance = getSingleton(beanName);
		if (singletonInstance instanceof SmartInitializingSingleton) {
			SmartInitializingSingleton smartSingleton = (SmartInitializingSingleton) singletonInstance;
			if (System.getSecurityManager() != null) {
				AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
					smartSingleton.afterSingletonsInstantiated();
					return null;
				}, getAccessControlContext());
			}
			else {
				smartSingleton.afterSingletonsInstantiated();
			}
		}
	}
}

3.12、finishRefresh()

完成 IoC 容器 创建的收尾工作

protected void finishRefresh() {
	// Clear context-level resource caches (such as ASM metadata from scanning).
	clearResourceCaches();

	// Initialize lifecycle processor for this context.
	initLifecycleProcessor();

	// Propagate refresh to lifecycle processor first.
	getLifecycleProcessor().onRefresh();

	// Publish the final event.
	publishEvent(new ContextRefreshedEvent(this));

	// Participate in LiveBeansView MBean, if active.
	LiveBeansView.registerApplicationContext(this);
}