Spring5源码 - refresh()方法

蔚落 2022-09-08 10:30 108阅读 0赞

refresh() 在 AbstractApplicationContext 类中。

public void refresh() throws BeansException, IllegalStateException { 
        synchronized (this.startupShutdownMonitor) { 
            // Prepare this context for refreshing.
            //1、刷新前的工作准备
            prepareRefresh();
    
            // Tell the subclass to refresh the internal bean factory.
            //2、获取子类刷新后的内部 beanFactory
            ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
    
            // Prepare the bean factory for use in this context.
            //3、为容器注册必要的系统级别的Bean，例如类加载器、事件处理器等
            prepareBeanFactory(beanFactory);
    
            try { 
                // Allows post-processing of the bean factory in context subclasses.
                //4、允许子类去注册 postProcessor
                postProcessBeanFactory(beanFactory);
    
                // Invoke factory processors registered as beans in the context.
                //5、调用容器注册的容器级别的后置处理器
                invokeBeanFactoryPostProcessors(beanFactory);
    
                // Register bean processors that intercept bean creation.
                //6、向容器注册Bean级别的后置处理器
                registerBeanPostProcessors(beanFactory);
    
                // Initialize message source for this context.
                //7、初始化国际化配置
                initMessageSource();
    
                // Initialize event multicaster for this context.
                //8、初始化容器事件发布者组件（传播器）
                initApplicationEventMulticaster();
    
                // Initialize other special beans in specific context subclasses.
                //9、在单例Bean初始化之前预留给子类初始化其他特殊bean的口子
                onRefresh();
    
                // Check for listener beans and register them.
                //10、为事件传播器注册事件监听器.
                registerListeners();
    
                // Instantiate all remaining (non-lazy-init) singletons.
                //11、设置系统级别的服务，实例化所有非懒加载的单例
                finishBeanFactoryInitialization(beanFactory);
    
                // Last step: publish corresponding event.
                //12、触发初始化完成的回调方法，并发布容器刷新完成的事件给监听者
                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.
                //13、销毁已创建的Bean
                destroyBeans();
    
                // Reset 'active' flag.
                //14、取消refresh操作，重置容器的同步标识。
                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...
                // 15、重置Spring内核中共用缓存
                resetCommonCaches();
            }
        }
    }