ApplicationContext的refresh过程

@Override
public void refresh() throws BeansException, IllegalStateException {
	synchronized (this.startupShutdownMonitor) {
		// Prepare this context for refreshing.
           //进行一些准备工作，比如环境变量的操作等等
		prepareRefresh();

		// Tell the subclass to refresh the internal bean factory.
           //获取beanFactory
		ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

		// Prepare the bean factory for use in this context.
           //对beanFactory进行一些必要的设置
		prepareBeanFactory(beanFactory);

		try {
			// Allows post-processing of the bean factory in context subclasses.
               //beanFactory的后处理
			postProcessBeanFactory(beanFactory);

			// Invoke factory processors registered as beans in the context.
               //调用beanFactory的后处理器，扩展点之一
			invokeBeanFactoryPostProcessors(beanFactory);

			// Register bean processors that intercept bean creation.
               //注册bean处理器，扩展点之一
			registerBeanPostProcessors(beanFactory);

			// Initialize message source for this context.
               //实例化消息源，
			initMessageSource();

			// Initialize event multicaster for this context.
               //初始化广播器
			initApplicationEventMulticaster();

			// Initialize other special beans in specific context subclasses.
               //留出为子类提供的扩展点，扩展点之一
			onRefresh();

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

			// Instantiate all remaining (non-lazy-init) singletons.
               //实例化非懒加载的单例
			finishBeanFactoryInitialization(beanFactory);

			// Last step: publish corresponding event.
               //发布相关事件
			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.
               //销毁bean
			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();
		}
	}
}

可以看到，spring的代码风格，先用方法列出逻辑框架，然后逐一进行填充，值得学习；

后面就每一步进行详细的补充。