Spring源码之ApplicationContext(十)过程刷新

ApplicationContext的初始化的最后一步就是要刷新过程，什么是刷新过程？其实Spring关闭的时候调用stop方法来结束生命周期，通常用来配置后台程序，在启动后一直运行（如对MQ进行轮询等）。我们先来看调用的时序图。（相关资源可到这里下载：http://pan.baidu.com/s/1sjSo9a9）

首先，Spring先调用的是finishRefresh()的方法。

/** * Finish the refresh of this context, invoking the LifecycleProcessor's * onRefresh() method and publishing the * {@link org.springframework.context.event.ContextRefreshedEvent}. */protected void finishRefresh() {// Initialize lifecycle processor for this context.initLifecycleProcessor();// Propagate refresh to lifecycle processor first.getLifecycleProcessor().onRefresh();// Publish the final event.publishEvent(new ContextRefreshedEvent(this));// Participate in LiveBeansView MBean, if active.LiveBeansView.registerApplicationContext(this);}

之后，我们会发现，Spring的ApplicationContext启动或停止时，它会通过LifecycleProcessor来与所有声明的bean的周期做状态，而LifecycleProcessor的使用前首先需要初始化。

/** * Initialize the LifecycleProcessor. * Uses DefaultLifecycleProcessor if none defined in the context. * @see org.springframework.context.support.DefaultLifecycleProcessor */protected void initLifecycleProcessor() {ConfigurableListableBeanFactory beanFactory = getBeanFactory();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 + "]");}}}

当做finishRefresh()方法，还有两个的方法调用也是值得我们去跟踪的，那就是onRefresh()的方法，及它间接调用了startBeans的方法。

@Overridepublic void onRefresh() {startBeans(true);this.running = true;}

private void startBeans(boolean autoStartupOnly) {Map<String, Lifecycle> lifecycleBeans = getLifecycleBeans();Map<Integer, LifecycleGroup> phases = new HashMap<Integer, LifecycleGroup>();for (Map.Entry<String, ? extends Lifecycle> entry : lifecycleBeans.entrySet()) {Lifecycle bean = entry.getValue();if (!autoStartupOnly || (bean instanceof SmartLifecycle && ((SmartLifecycle) bean).isAutoStartup())) {int phase = getPhase(bean);LifecycleGroup group = phases.get(phase);if (group == null) {group = new LifecycleGroup(phase, this.timeoutPerShutdownPhase, lifecycleBeans, autoStartupOnly);phases.put(phase, group);}group.add(entry.getKey(), bean);}}if (phases.size() > 0) {List<Integer> keys = new ArrayList<Integer>(phases.keySet());Collections.sort(keys);for (Integer key : keys) {phases.get(key).start();}}}

 最后，我们来看一下publishEvent的源码。

/** * Publish the given event to all listeners. * @param event the event to publish (may be an {@link ApplicationEvent} * or a payload object to be turned into a {@link PayloadApplicationEvent}) * @param eventType the resolved event type, if known * @since 4.2 */protected void publishEvent(Object event, ResolvableType eventType) {Assert.notNull(event, "Event must not be null");if (logger.isTraceEnabled()) {logger.trace("Publishing event in " + getDisplayName() + ": " + event);}// Decorate event as an ApplicationEvent if necessaryApplicationEvent applicationEvent;if (event instanceof ApplicationEvent) {applicationEvent = (ApplicationEvent) event;}else {applicationEvent = new PayloadApplicationEvent<Object>(this, event);if (eventType == null) {eventType = ((PayloadApplicationEvent)applicationEvent).getResolvableType();}}// Multicast right now if possible - or lazily once the multicaster is initializedif (this.earlyApplicationEvents != null) {this.earlyApplicationEvents.add(applicationEvent);}else {getApplicationEventMulticaster().multicastEvent(applicationEvent, eventType);}// Publish event via parent context as well...if (this.parent != null) {if (this.parent instanceof AbstractApplicationContext) {((AbstractApplicationContext) this.parent).publishEvent(event, eventType);}else {this.parent.publishEvent(event);}}}