13-Spring refresh parsing the source (6) - initMessageSource [] and [] initApplicationEventMulticaster

Previous: Refresh the Spring-12 is the parse source (5) - registerBeanPostProcessors

Previous analysis we finished registerBeanPostProcessors, then we begin to analyze refreshthe methods of the seventh initMessageSourceand eighth methodsinitApplicationEventMulticaster

One,initMessageSource

Initialization MessageSourcecomponent (make binding message, message parsing)

	protected void initMessageSource() {
		ConfigurableListableBeanFactory beanFactory = getBeanFactory();
		// 判断是否已经存在名为messageSource的Bean了
		if (beanFactory.containsLocalBean(MESSAGE_SOURCE_BEAN_NAME)) {
			this.messageSource = beanFactory.getBean(MESSAGE_SOURCE_BEAN_NAME, MessageSource.class);
			// Make MessageSource aware of parent MessageSource.
			if (this.parent != null && this.messageSource instanceof HierarchicalMessageSource) {
				HierarchicalMessageSource hms = (HierarchicalMessageSource) this.messageSource;
				if (hms.getParentMessageSource() == null) {
					// Only set parent context as parent MessageSource if no parent MessageSource
					// registered already.
					hms.setParentMessageSource(getInternalParentMessageSource());
				}
			}
			if (logger.isTraceEnabled()) {
				logger.trace("Using MessageSource [" + this.messageSource + "]");
			}
		}
		else {
			// Use empty MessageSource to be able to accept getMessage calls.
			DelegatingMessageSource dms = new DelegatingMessageSource();
			// 获取父容器的messageSource字段
			// 一般都为空
			dms.setParentMessageSource(getInternalParentMessageSource());
			this.messageSource = dms;
			// ----------该方法的核心---------------
			//  把MessageSource注入到容器中，以后获取国际化配置文件值的时候，可以自动注入MessageSource
			beanFactory.registerSingleton(MESSAGE_SOURCE_BEAN_NAME, this.messageSource);
			if (logger.isTraceEnabled()) {
				logger.trace("No '" + MESSAGE_SOURCE_BEAN_NAME + "' bean, using [" + this.messageSource + "]");
			}
		}
	}

	// 取出国际化配置文件中的某个key值(可以按住区域信息获取)
	protected MessageSource getInternalParentMessageSource() {
		return (getParent() instanceof AbstractApplicationContext ?
				((AbstractApplicationContext) getParent()).messageSource : getParent());
	}

1.1 registerSingleton

	public void registerSingleton(String beanName, Object singletonObject) throws IllegalStateException {
		super.registerSingleton(beanName, singletonObject);
		updateManualSingletonNames(set -> set.add(beanName), set -> !this.beanDefinitionMap.containsKey(beanName));
		clearByTypeCache();
	}

You must first call the parent classregisterSingleton

	public void registerSingleton(String beanName, Object singletonObject) throws IllegalStateException {
		Assert.notNull(beanName, "Bean name must not be null");
		Assert.notNull(singletonObject, "Singleton object must not be null");
		synchronized (this.singletonObjects) {
			Object oldObject = this.singletonObjects.get(beanName);
			if (oldObject != null) {
				throw new IllegalStateException("Could not register object [" + singletonObject +
						"] under bean name '" + beanName + "': there is already object [" + oldObject + "] bound");
			}
			addSingleton(beanName, singletonObject);
		}
	}

The beanNameand singletonObjectadded to singletonObjects, and registeredSingletonsin and from singletonFactoriesand earlySingletonObjectsto remove the. It involves a method for storing Beanfour different of Map. It should be a simple explanation. In the creation of these Beanwill be frequently used time for resolve circular dependencies, caches and other issues.

• singletonObjects: To save beanNameand beanrelationships between instances
• singletonFactories: To save beanNameand create beanrelationships between plants
• earlySingletonObjects: To save beanNameand beanrelationships between instances, the singletonObjectsdifference is that: when a single interest beanafter being placed there, then when beanstill in the process of creating species, it can getBeanobtain the method, purpose is to check cycle dependent .
• registeredSingletons: To save all the current already created bean.

	protected void addSingleton(String beanName, Object singletonObject) {
		synchronized (this.singletonObjects) {
			this.singletonObjects.put(beanName, singletonObject);
			this.singletonFactories.remove(beanName);
			this.earlySingletonObjects.remove(beanName);
			this.registeredSingletons.add(beanName);
		}
	}

In the initMessageSourceimplementation of the latter, we look at beanFactorythe registeredSingletonsvalue of the property

• registeredSingletons[0] – registeredSingletons[2]

  • In refresh> - prepareBeanFactoryregistration process

• registeredSingletons[3]–registeredSingletons[6]

  • In refresh> - invokeBeanFactoryPostProcessorsregistration process

• registeredSingletons[7]–registeredSingletons[10]

  • In refresh> - registerBeanPostProcessorsregistration process

• registeredSingletons[11]

  • In refresh> - initMessageSourceregistration process

Second, the initApplicationEventMulticasterevent dispatcher

	protected void initApplicationEventMulticaster() {
		ConfigurableListableBeanFactory beanFactory = getBeanFactory();
		if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {
			this.applicationEventMulticaster =
					beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);
			if (logger.isTraceEnabled()) {
				logger.trace("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");
			}
		}
		else {
			this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
			beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);
			if (logger.isTraceEnabled()) {
				logger.trace("No '" + APPLICATION_EVENT_MULTICASTER_BEAN_NAME + "' bean, using " +
						"[" + this.applicationEventMulticaster.getClass().getSimpleName() + "]");
			}
		}
	}

With initMessageSourcesimilar methods, it not described in detail here. After a look at the implementation of the method beanFactoryof the registeredSingletonsvalue of the property of

beanFactoryOf registeredSingletonsthe property more applicationEventMulticaster.

Next article we explain refreshthe ninth methods onRefreshand tenth methods registerListeners.