【Spring源码解析】 IOC 初始化流程分析

1 .AbstractApplicationContext prepareBeanFactory

@Override
    public void refresh() throws BeansException, IllegalStateException {
        synchronized (this.startupShutdownMonitor) {
            //刷新前预处理
            prepareRefresh();

            //获取beanFactory实例。(DefaultListableBeanFactory)
            ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

            //beanFactory属性赋值
            prepareBeanFactory(beanFactory);

            try {
                // 子类通过重写这个方法在BeanFactory创建并预准备完成以后做进一步设置
                postProcessBeanFactory(beanFactory);

                // 调用实现BeanDefinitionRegistryPostProcessor，BeanFactoryPostProcessor 接口的类相关方法
                invokeBeanFactoryPostProcessors(beanFactory);
               
                // 注册实现了BeanPostProcessor接口的Bean
                registerBeanPostProcessors(beanFactory);

                // 标签国际化资源，初始化MessageSource组件
                initMessageSource();
  
                // 创建事件广播器
                initApplicationEventMulticaster();
  
                // 空方法，留给子容器实现，在容器刷新的时候可以子定义逻辑    
                onRefresh();
  
               // 注册监听器事件
                registerListeners();
 
               // 单例模式bean的注册
                finishBeanFactoryInitialization(beanFactory);

                // 刷新完成容器
                finishRefresh();
            }
            catch (BeansException ex) {
                if (logger.isWarnEnabled()) {
                    logger.warn("Exception encountered during context initialization - " +
                            "cancelling refresh attempt: " + ex);
                }
                // Destroy already created singletons to avoid dangling resources.
                destroyBeans();
                // Reset 'active' flag.
                cancelRefresh(ex);
                // Propagate exception to caller.
                throw ex;
            }
            finally {
                // Reset common introspection caches in Spring's core, since we
                // might not ever need metadata for singleton beans anymore...
                resetCommonCaches();
            }
        }
    }     

2 核心方法解析

2.1 obtainFreshBeanFactory() 获取BeanFactory

(1) AbstractApplicationContext obtainFreshBeanFactory

protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
   //刷新容器
   refreshBeanFactory();
   //获取GenericApplicationContext创建的容器
   ConfigurableListableBeanFactory beanFactory = getBeanFactory();
   if (logger.isDebugEnabled()) {
      logger.debug("Bean factory for " + getDisplayName() + ": " + beanFactory);
   }
   return beanFactory;
}

GenericApplicationContext refreshBeanFactory()

2.2 invokeBeanFactoryPostProcessors(beanFactory)

实际调用PostProcessorRegistrationDelegate invokeBeanFactoryPostProcessors
(1) 调用实现BeanDefinitionRegistryPostProcessor接口的postProcessBeanDefinitionRegistry，postProcessBeanFactory方法
(2) 调用实现类BeanFactoryPostProcessor接口的postProcessBeanFactory方法
 PS：BeanFactoryPostProcessor源码机票  -------> https://blog.csdn.net/qq_34125999/article/details/104645988

2.3 registerBeanPostProcessors(beanFactory);

实际调用PostProcessorRegistrationDelegate  registerBeanPostProcessors，其作用就是给工厂中添加实现了BeanPostProcessor接口的bean
PS：源码机票  ------->  https://blog.csdn.net/qq_34125999/article/details/104572875

2.4 finishBeanFactoryInitialization(beanFactory);

完成单实例Bean的注册。
PS：源码机票  ------->  https://blog.csdn.net/qq_34125999/article/details/104547157

3 单例Bean注册的位置