spring加载流程之refresh()

转载自

https://blog.csdn.net/yu_kang/article/details/88076796

public void refresh() throws BeansException, IllegalStateException {
		synchronized (this.startupShutdownMonitor) {
			// Prepare this context for refreshing.

			/**
			 * 准备刷新：
			 * 设置启动时间、是否激活标识位
			 * 初始化属性源（property source）配置
			 */
			prepareRefresh();

			// Tell the subclass to refresh the internal bean factory.
			/**
			 * 获取一个BeanFactory
			 * 拿到DefaultListableBeanFactory,供后面方法调用
			 */
			ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

			// Prepare the bean factory for use in this context.
			/**
			 * 对beanFactory进行相关的参数设置，包括classLoader，expressionResolver，注入一些spirng 内部的bean,aware接口等
			 */
			prepareBeanFactory(beanFactory);

			try {
				// Allows post-processing of the bean factory in context subclasses.
				/**
				 * 这个方法在当前版本没有实现
				 * 可能在spring后面的版本会去扩展
				 */
				postProcessBeanFactory(beanFactory);

				// Invoke factory processors registered as beans in the context.
				/**
				 * 在上下文中调用注册为bean的工厂处理器
				 *
				 * 添加BeanPostProcessor
				 * 如果发现loadTimeWeaver的Bean
				 */
				invokeBeanFactoryPostProcessors(beanFactory);

				// Register bean processors that intercept bean creation.
				/**
				 * 注册BeanPostProcessor
				 * 自定义以及spring内部的
				 */
				registerBeanPostProcessors(beanFactory);

				// Initialize message source for this context.
				/**
				 * 国际化支持，不关心
				 */
				initMessageSource();

				// Initialize event multicaster for this context.
				/**
				 * 初始化事件监听多路广播器
				 */
				initApplicationEventMulticaster();

				// Initialize other special beans in specific context subclasses.
				/**
				 * 这个方法在当前版本没有实现
				 * 可能在spring后面的版本会去扩展
				 */
				onRefresh();

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

				// Instantiate all remaining (non-lazy-init) singletons.
				/**
				 * 实例化所有bean
				 */
				finishBeanFactoryInitialization(beanFactory);

				// Last step: publish corresponding event.
				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();
			}
		}
	}
}