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目录
代码块1:applyMergedBeanDefinitionPostProcessors
代码块6:unsatisfiedNonSimpleProperties
代码块13:applyBeanPostProcessorsBeforeInitialization
代码块14:postProcessBeforeInitialization
代码块17:applyBeanPostProcessorsAfterInitialization
代码块18:registerDisposableBeanIfNecessary
代码块23:inferDestroyMethodIfNecessary
Spring IoC源码学习全系列
Spring IoC源码学习:ApplicationContext 刷新前的配置
Spring IoC源码学习:obtainFreshBeanFactory详解
Spring IoC源码学习:parseDefaultElement详解
Spring IoC源码学习:parseCustomElement详解
Spring IoC源码学习:context:component-scan 节点详解
Spring IoC源码学习:invokeBeanFactoryPostProcessors详解
Spring IoC源码学习:registerBeanPostProcessors详解
Spring IoC源码学习:finishBeanFactoryInitialization详解
Spring IoC源码学习:createBean详解(上)
Spring IoC源码学习:createBean详解(下)
Spring IoC源码学习:finishRefresh 详解
前言
接着 Spring IoC:createBean详解(上),我们继续解析创建 bean 实例的剩下内容。
正文
首先,我们回到 Spring IoC:createBean详解(上)中的代码块3,doCreateBean 方法。
doCreateBean
protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final Object[] args)
throws BeanCreationException {
// Instantiate the bean.
// 1.新建Bean包装类
BeanWrapper instanceWrapper = null;
if (mbd.isSingleton()) {
// 2.如果是FactoryBean,则需要先移除未完成的FactoryBean实例的缓存
instanceWrapper = this.factoryBeanInstanceCache.remove(beanName);
}
if (instanceWrapper == null) {
// 3.根据beanName、mbd、args,使用对应的策略创建Bean实例,并返回包装类BeanWrapper
instanceWrapper = createBeanInstance(beanName, mbd, args);
}
// 4.拿到创建好的Bean实例
final Object bean = (instanceWrapper != null ? instanceWrapper.getWrappedInstance() : null);
// 5.拿到Bean实例的类型
Class<?> beanType = (instanceWrapper != null ? instanceWrapper.getWrappedClass() : null);
mbd.resolvedTargetType = beanType;
// Allow post-processors to modify the merged bean definition.
synchronized (mbd.postProcessingLock) {
if (!mbd.postProcessed) {
try {
// 6.应用后置处理器MergedBeanDefinitionPostProcessor,允许修改MergedBeanDefinition,
// Autowired注解正是通过此方法实现注入类型的预解析
applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);
} catch (Throwable ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"Post-processing of merged bean definition failed", ex);
}
mbd.postProcessed = true;
}
}
// Eagerly cache singletons to be able to resolve circular references
// even when triggered by lifecycle interfaces like BeanFactoryAware.
// 7.判断是否需要提早曝光实例:单例 && 允许循环依赖 && 当前bean正在创建中
boolean earlySingletonExposure = (mbd.isSingleton() && this.allowCircularReferences &&
isSingletonCurrentlyInCreation(beanName));
if (earlySingletonExposure) {
if (logger.isDebugEnabled()) {
logger.debug("Eagerly caching bean '" + beanName +
"' to allow for resolving potential circular references");
}
// 8.提前曝光beanName的ObjectFactory,用于解决循环引用
addSingletonFactory(beanName, new ObjectFactory<Object>() {
@Override
public Object getObject() throws BeansException {
// 8.1 应用后置处理器SmartInstantiationAwareBeanPostProcessor,允许返回指定bean的早期引用,若没有则直接返回bean
return getEarlyBeanReference(beanName, mbd, bean);
}
});
}
// Initialize the bean instance.