Spring源码-05-容器refresh

一 refresh

// AbstractApplicationContext.java
@Override
    public void refresh() throws BeansException, IllegalStateException {
        synchronized (this.startupShutdownMonitor) {
            StartupStep contextRefresh = this.applicationStartup.start("spring.context.refresh");

            // Prepare this context for refreshing.
            /**
             * 1 容器启动前置准备
             */
            this.prepareRefresh();

            // Tell the subclass to refresh the internal bean factory.
            /**
             * 模板方法
             * 从子类的实现(GenericApplicationContext)获取Bean工厂beanFactory(DefaultListableBeanFactory)
             */
            ConfigurableListableBeanFactory beanFactory = this.obtainFreshBeanFactory();

            // Prepare the bean factory for use in this context.
            /**
             * 2 Bean工厂前置准备
             */
            this.prepareBeanFactory(beanFactory);

            try {
                // Allows post-processing of the bean factory in context subclasses.
                /**
                 * 3 空实现
                 */
                this.postProcessBeanFactory(beanFactory);

                StartupStep beanPostProcess = this.applicationStartup.start("spring.context.beans.post-process");
                // Invoke factory processors registered as beans in the context.
                /**
                 * 4 调用所有注册的BeanFactoryPostProcessor的实例
                 *     - BeanFactoryPostProcessor
                 *     - BeanDefinitionRegistryPostProcessor
                 * Bean工厂后置处理器职责
                 *     - 作用对象是Bean工厂
                 *     - 现在还没有将用户BeanDefinition注册到Bean工厂中
                 *     - 特定的后置处理器作用是将用户BeanDefinition注册Bean工厂中
                 * ConfigurationClassPostProcessor作用的时机
                 *     - 解析配置类
                 *     - 注册BeanDefinition到Bean工厂
                 *     - 增强full型配置类
                 *     - 向Bean工厂注册一个Bean后置处理器ImportAwareBeanPostProcessor
                 */
                this.invokeBeanFactoryPostProcessors(beanFactory);

                // Register bean processors that intercept bean creation.
                /**
                 * 5 Bean实例化初始化之前将后置处理器注册到容器中
                 * 后置处理器的职责
                 *     - BeanDefinition都已经注册到了Bean工厂中(DefaultListableBeanFactory的beanDefinitionMap)
                 *     - Spring可以根据BeanDefinition进行Bean的实例化和初始化
                 *     - 在此之前注册Bean的后置处理器
                 *         - 在Bean实例化前后回调
                 *         - 在Bean初始化前后回调
                 * 上面Bean工厂后置处理器执行结束之后 就已经将BeanDefinition都注册到Bean工厂beanDefinitionMap中了
                 * 现在将所有Bean工厂中BeanDefinition中是Bean后置处理器的都进行实例化注册到Bean工厂的beanPostProcessors中
                 */
                registerBeanPostProcessors(beanFactory);
                beanPostProcess.end();

                // Initialize message source for this context.
                /**
                 * 6 初始化信息源
                 *     - 国际化
                 */
                initMessageSource();

                // Initialize event multicaster for this context.
                /**
                 * 7 初始化容器事件传播器
                 */
                initApplicationEventMulticaster();

                // Initialize other special beans in specific context subclasses.
                /**
                 * 8 特定上下文子类中初始化特殊的Bean
                 */
                onRefresh();

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

                // Instantiate all remaining (non-lazy-init) singletons.
                /**
                 * 10 实例化非延迟初始化单例
                 */
                finishBeanFactoryInitialization(beanFactory);

                // Last step: publish corresponding event.
                /**
                 * 11 初始化容器生命周期事件处理器 发布容器生命周期事件
                 */
                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();
                contextRefresh.end();
            }
        }
    }

二 步骤

三 示意图

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