容器的功能擴充（三）finishRefresh

在Spring中還提供了Lifecycle接口，Lifecycle中包含start/stop方法，實作此接口後Spring會保證在啟動的時候調用其start方法開始生命周期，并在Spring關閉的時候調用stop方法來結束生命周期，通常用來配置背景程式，在啟動後一直運作.而ApplicationContext的初始化最後正是保證了這一功能的實作。

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);
	}
           

1.initLifecycleProcessor

/**
	 * 當ApplicationContext啟動或停止時，它會通過LifecycleProcessor來與所有聲明的bean的
	 * 周期做狀态更新，而在LifecycleProcessor的使用前需要先初始化
	 */
	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 + "]");
			}
		}
	}
           

2.onRefresh

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

啟動所有實作了Lifecycle接口的bean.

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();
			}
		}
	}
           

3.publishEvent

當完成ApplicationContext初始化的時候，要通過Spring中的時間釋出機制發出ContextRefreshedEvent事件，以保證對應的監聽器可以做進一步的邏輯處理

public void publishEvent(ApplicationEvent event) {
		Assert.notNull(event, "Event must not be null");
		if (logger.isTraceEnabled()) {
			logger.trace("Publishing event in " + getDisplayName() + ": " + event);
		}
		getApplicationEventMulticaster().multicastEvent(event);
		if (this.parent != null) {
			this.parent.publishEvent(event);
		}
	}
           

至此為止，關于SpringIOC的一些東西可以劃一個句号了，後面我們一起來分析一下關于SpringJDBC方面的知識