参考源
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
本文章基于 Spring 5.3.15
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 11 个：
finishBeanFactoryInitialization。
1 AbstractApplicationContext
1-1 初始化剩下的单实例
finishBeanFactoryInitialization(beanFactory)
protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
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));
}
if (!beanFactory.hasEmbeddedValueResolver()) {
beanFactory.addEmbeddedValueResolver(strVal -> getEnvironment().resolvePlaceholders(strVal));
}
String[] weaverAwareNames = beanFactory.getBeanNamesForType(LoadTimeWeaverAware.class, false, false);
for (String weaverAwareName : weaverAwareNames) {
getBean(weaverAwareName);
}
beanFactory.setTempClassLoader(null);
// 冻结所有的 bean 定义，说明注册的 bean 定义将不被修改或任何进一步的处理
beanFactory.freezeConfiguration();
// 初始化剩下的单实例（非惰性的）
beanFactory.preInstantiateSingletons();
}
1-2 冻结所有的 bean 定义
beanFactory.freezeConfiguration()
2 DefaultListableBeanFactory
public void freezeConfiguration() {
this.configurationFrozen = true;
this.frozenBeanDefinitionNames = StringUtils.toStringArray(this.beanDefinitionNames);
}
1 AbstractApplicationContext
1-2 初始化剩下的单实例
beanFactory.preInstantiateSingletons()
2 DefaultListableBeanFactory
public void preInstantiateSingletons() throws BeansException {
if (logger.isTraceEnabled()) {
logger.trace("Pre-instantiating singletons in " + this);
}
List<String> beanNames = new ArrayList<>(this.beanDefinitionNames);
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 {
getBean(beanName);
}
}
}
for (String beanName : beanNames) {
Object singletonInstance = getSingleton(beanName);
if (singletonInstance instanceof SmartInitializingSingleton) {
StartupStep smartInitialize = this.getApplicationStartup().start("spring.beans.smart-initialize").tag("beanName", beanName);
SmartInitializingSingleton smartSingleton = (SmartInitializingSingleton) singletonInstance;
if (System.getSecurityManager() != null) {
AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
smartSingleton.afterSingletonsInstantiated();
return null;
}, getAccessControlContext());
}
else {
smartSingleton.afterSingletonsInstantiated();
}
smartInitialize.end();
}
}
}
