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文章目录
前言
finishBeanFactoryInitialization(beanFactory)
主要是实例化所有满足条件的单例 Bean
AbstractApplicationContext.finishBeanFactoryInitialization(beanFactory);
protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
...
// Allow for caching all bean definition metadata, not expecting further changes.
// 冻结所有 BeanDefinition, 将一个标记置为 true, 表示要开始生产 Bean 了
beanFactory.freezeConfiguration();
// Instantiate all remaining (non-lazy-init) singletons.
// 实例化剩余的单例 Bean
beanFactory.preInstantiateSingletons();
}
DefaultListableBeanFactory.preInstantiateSingletons();
@Override
public void preInstantiateSingletons() throws BeansException {
if (logger.isTraceEnabled()) {
logger.trace("Pre-instantiating singletons in " + this);
}
// 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);
// 遍历所有 BeanDefinition, 非抽象,单例,非懒加载 的才会被初始化
if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
// 判断是否为 FactoryBean
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
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();
}
}
}
}