Spring容器初始化AbstractApplicationContext說明

看下面的代碼注釋

@Override
	public void refresh() throws BeansException, IllegalStateException {
		synchronized (this.startupShutdownMonitor) {
			// Prepare this context for refreshing.
			// 為上下文做重新整理
			prepareRefresh();

			// Tell the subclass to refresh the internal bean factory.  告訴子類重新整理内部bean工廠
			ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

			// Prepare the bean factory for use in this context.  準備bean工廠
			prepareBeanFactory(beanFactory);

			try {
				// Allows post-processing of the bean factory in context subclasses.  允許在上下文子類中對bean工廠進行後處理。
				postProcessBeanFactory(beanFactory);

				// Invoke factory processors registered as beans in the context. 設定bean工廠處理器
				invokeBeanFactoryPostProcessors(beanFactory);

				// Register bean processors that intercept bean creation. 注冊bean處理攔截器
				registerBeanPostProcessors(beanFactory);

				// Initialize message source for this context.
				// 初始化消息源
				initMessageSource();

				// Initialize event multicaster for this context.  初始化事件廣播器
				initApplicationEventMulticaster();

				// Initialize other special beans in specific context subclasses.  初始化一下特殊bean
				onRefresh();

				// Check for listener beans and register them.  注冊監聽執行個體
				registerListeners();

				// Instantiate all remaining (non-lazy-init) singletons.  執行個體化所有剩餘的（非lazy init）單例
				finishBeanFactoryInitialization(beanFactory);

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

總結

簡要來說分為下面幾個步驟：

• 重新整理預處理
• 解析配置資訊 注冊BeanFactory
• 設定bean 類加載器
• bean加載前後自定義想做的事
• 初始化事件廣播器
• 初始化所有bean
• 廣播applicationcontext初始化完成