很早就看过spring IoC容器源码，一直没时间做系统的整理，现在大概整理下：
核心类关系： ClassPathXmlApplicationContext extends AbstractXmlApplicationContext AbstractXmlApplicationContext extends AbstractRefreshableConfigApplicationContext AbstractRefreshableConfigApplicationContext extends AbstractRefreshableApplicationContext AbstractRefreshableApplicationContext extends AbstractApplicationContext AbstractApplicationContext extends DefaultResourceLoader DefaultResourceLoader implements ResourceLoader private DefaultListableBeanFactory AbstractRefreshableApplicationContext.beanFactory;
大概流程：
//ClassPathXmlApplicationContext 构造 public ClassPathXmlApplicationContext(String[] configLocations, boolean refresh, ApplicationContext parent) throws BeansException { super(parent); //对configLocations 加载路径的处理 调用了 AbstractRefreshableConfigApplicationContext.setConfigLocations this.setConfigLocations(configLocations); if (refresh) { //这是核心 刷新context 调用了AbstractApplicationContext.refresh this.refresh(); } } //AbstractRefreshableConfigApplicationContext.setConfigLocations public void setConfigLocations(String[] locations) { if (locations != null) { Assert.noNullElements(locations, "Config locations must not be null"); this.configLocations = new String[locations.length]; for(int i = 0; i < locations.length; ++i) { //这里解析路径 替换占位符 this.configLocations[i] = this.resolvePath(locations[i]).trim(); } } else { this.configLocations = null; } } //AbstractRefreshableConfigApplicationContext.resolvePath protected String resolvePath(String path) { return SystemPropertyUtils.resolvePlaceholders(path); } //AbstractApplicationContext.refresh public void refresh() throws BeansException, IllegalStateException { synchronized(this.startupShutdownMonitor) { //准备刷新 这里记录了startupDate=now active=true 两个变量 this.prepareRefresh(); //获取 BeanFactory 及bean的定义 ConfigurableListableBeanFactory beanFactory = this.obtainFreshBeanFactory(); //初始化 BeanFactory 设定一些参数 this.prepareBeanFactory(beanFactory); try { //如果有需要-留给子类实现的空方法 this.postProcessBeanFactory(beanFactory); //执行 BeanFactoryPostProcessor 相关bean this.invokeBeanFactoryPostProcessors(beanFactory); //从bean工厂中找到实现了BeanPostProcessor的bean实例化并注册BeanPostProcessor this.registerBeanPostProcessors(beanFactory); //初始化 MessageSource 自定义可用messageSource作为beanName this.initMessageSource(); //初始化ApplicationEventMulticaster事件广播器 //自定义可用applicationEventMulticaster作为beanName this.initApplicationEventMulticaster(); //如果有需要-留给子类实现的空方法 this.onRefresh(); //注册 ApplicationListener this.registerListeners(); //加载所有剩余的（非延迟）单例Bean this.finishBeanFactoryInitialization(beanFactory); //发布事件 this.finishRefresh(); } catch (BeansException var4) { this.destroyBeans(); this.cancelRefresh(var4); throw var4; } } } //AbstractApplicationContext.obtainFreshBeanFactory protected ConfigurableListableBeanFactory obtainFreshBeanFactory() { //刷新BeanFactory 主要作用是销毁原来的 BeanFactory 并创建新的 this.refreshBeanFactory(); //从this.beanFactory获取当前BeanFactory ConfigurableListableBeanFactory beanFactory = this.getBeanFactory(); if (this.logger.isDebugEnabled()) { this.logger.debug("Bean factory for " + this.getDisplayName() + ": " + beanFactory); } return beanFactory; } //AbstractRefreshableApplicationContext.refreshBeanFactory protected final void refreshBeanFactory() throws BeansException { if (this.hasBeanFactory()) { / this.destroyBeans(); this.closeBeanFactory(); } try { //创建新的beanFactory DefaultListableBeanFactory beanFactory = this.createBeanFactory(); beanFactory.setSerializationId(this.getId()); this.customizeBeanFactory(beanFactory); //从xml加载bean定义 this.loadBeanDefinitions(beanFactory); synchronized(this.beanFactoryMonitor) { this.beanFactory = beanFactory; } } catch (IOException var4) { throw new ApplicationContextException("I/O error parsing bean definition source for " + this.getDisplayName(), var4); } } //AbstractApplicationContext.finishRefresh protected void finishRefresh() { //初始化 lifecycleProcessor initLifecycleProcessor(); //lifecycleProcessor.onRefresh getLifecycleProcessor().onRefresh(); //发布ApplicationContext刷新事件 publishEvent(new ContextRefreshedEvent(this)); } //AbstractApplicationContext.initApplicationEventMulticaster //APPLICATION_EVENT_MULTICASTER_BEAN_NAME="applicationEventMulticaster" protected void initApplicationEventMulticaster() { ConfigurableListableBeanFactory beanFactory = getBeanFactory(); //给自定义ApplicationEventMulticaster留的位置 APPLICATION_EVENT_MULTICASTER_BEAN_NAME if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) { this.applicationEventMulticaster = beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class); if (logger.isDebugEnabled()) { logger.debug("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]"); } } else { this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory); beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster); if (logger.isDebugEnabled()) { logger.debug("Unable to locate ApplicationEventMulticaster with name '" + APPLICATION_EVENT_MULTICASTER_BEAN_NAME + "': using default [" + this.applicationEventMulticaster + "]"); } } } //AbstractApplicationContext.finishRefresh protected void finishRefresh() { // 初始化Context生命周期 Processer initLifecycleProcessor(); getLifecycleProcessor().onRefresh(); //推送 publishEvent(new ContextRefreshedEvent(this)); } //AbstractApplicationContext.initLifecycleProcessor //LIFECYCLE_PROCESSOR_BEAN_NAME="lifecycleProcessor" protected void initLifecycleProcessor() { //初始化Context生命周期 bean ConfigurableListableBeanFactory beanFactory = getBeanFactory(); //给LifecycleProcessor留的位置LIFECYCLE_PROCESSOR_BEAN_NAME if (beanFactory.containsLocalBean(LIFECYCLE_PROCESSOR_BEAN_NAME)) { this.lifecycleProcessor = beanFactory.getBean(LIFECYCLE_PROCESSOR_BEAN_NAME, LifecycleProcessor.class); if (logger.isDebugEnabled()) { logger.debug("Using LifecycleProcessor [" + this.lifecycleProcessor + "]"); } } else { DefaultLifecycleProcessor defaultProcessor = new DefaultLifecycleProcessor(); defaultProcessor.setBeanFactory(beanFactory); this.lifecycleProcessor = defaultProcessor; beanFactory.registerSingleton(LIFECYCLE_PROCESSOR_BEAN_NAME, this.lifecycleProcessor); if (logger.isDebugEnabled()) { logger.debug("Unable to locate LifecycleProcessor with name '" + LIFECYCLE_PROCESSOR_BEAN_NAME + "': using default [" + this.lifecycleProcessor + "]"); } } }