源码来源于AbstractApplicationContext类：
@Override public void refresh() throws BeansException, IllegalStateException { synchronized (this.startupShutdownMonitor) { // Prepare this context for refreshing. prepareRefresh(); //1.创建真正的Spring容器（DefaultListableBeanFactory） //2.加载BeanDefition（描述要初始化的Bean的信息） //3.将BeanDefition注册到BeanDefitionRegistry // Tell the subclass to refresh the internal bean factory. ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory(); // Prepare the bean factory for use in this context. prepareBeanFactory(beanFactory); try { // Allows post-processing of the bean factory in context subclasses. postProcessBeanFactory(beanFactory); //执行实现了BeanFactoryPostProcessor接口的Bean //比如PropertyPlaceHolderConfigurer（context:property-placeholer）就是此处被调用的，替换掉BeanDefition中的占位符（${}）中的内容 // Invoke factory processors registered as beans in the context. invokeBeanFactoryPostProcessors(beanFactory); //注册BeanPostProcessor（后置处理器） //比如容器自动装载了一个AutowiredAnnotationBeanPostProcessor后置处理器（实现@Autowired注解功能） // Register bean processors that intercept bean creation. registerBeanPostProcessors(beanFactory); // Initialize message source for this context. initMessageSource(); // Initialize event multicaster for this context. initApplicationEventMulticaster(); // Initialize other special beans in specific context subclasses. onRefresh(); // Check for listener beans and register them. registerListeners(); //初始化非懒加载方式的单例Bean实例 // Instantiate all remaining (non-lazy-init) singletons. 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(); } } }