【Spring-4】refresh方法之finishBeanFactoryInitialization

该方法主要分析下实例化bean的逻辑

	protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
		// 实例化ConversionService类型的类
		if (beanFactory.containsBean(CONVERSION_SERVICE_BEAN_NAME) &&
				beanFactory.isTypeMatch(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class)) {
			beanFactory.setConversionService(
					beanFactory.getBean(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class));
		}

	
		if (!beanFactory.hasEmbeddedValueResolver()) {
			beanFactory.addEmbeddedValueResolver(strVal -> getEnvironment().resolvePlaceholders(strVal));
		}

		// 实例化LoadTimeWeaverAware类型的类
		String[] weaverAwareNames = beanFactory.getBeanNamesForType(LoadTimeWeaverAware.class, false, false);
		for (String weaverAwareName : weaverAwareNames) {
			getBean(weaverAwareName);
		}

		// Stop using the temporary ClassLoader for type matching.
		beanFactory.setTempClassLoader(null);

		// Allow for caching all bean definition metadata, not expecting further changes.
		beanFactory.freezeConfiguration();

		// 初始化所有非懒加载的类。
		beanFactory.preInstantiateSingletons();
	}

进入到beanFactory.preInstantiateSingletons();方法里

	@Override
	public void preInstantiateSingletons() throws BeansException {
		if (logger.isTraceEnabled()) {
			logger.trace("Pre-instantiating singletons in " + this);
		}

		// beanDefinitionNames为所有注册的bd名称
		List<String> beanNames = new ArrayList<>(this.beanDefinitionNames);

		// 遍历所有的bd
		for (String beanName : beanNames) {
			// 合并bd,如果有继承关系的，先找到父bd,之后把子bd的属性信息赋值给父bd
			RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
			// 非抽象，单例，非懒加载
			if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
				// 如果是FactoryBean类型。
				if (isFactoryBean(beanName)) {
					// 先实例化FactoryBean
					Object bean = getBean(FACTORY_BEAN_PREFIX + beanName);
					
					if (bean instanceof FactoryBean) {
						// 先查看是否需要实例化getObejct方法中的对象。
						FactoryBean<?> factory = (FactoryBean<?>) bean;
						boolean isEagerInit;
						// 根据不同的条件判断是否需要提前实例化。
						if (System.getSecurityManager() != null && factory instanceof SmartFactoryBean) {
							isEagerInit = AccessController.doPrivileged(
									(PrivilegedAction<Boolean>) ((SmartFactoryBean<?>) factory)::isEagerInit,
									getAccessControlContext());
						}
						else {
							isEagerInit = (factory instanceof SmartFactoryBean &&
									((SmartFactoryBean<?>) factory).isEagerInit());
						}
						
						// 如果需要提前实例化，则进行实例化操作。
						if (isEagerInit) {
							getBean(beanName);
						}
					}
				}


				//如果不是FactoryBean类型的，直接实例化。
				else {
					getBean(beanName);
				}
			}
		}

		// 此时已经完成了所有注册bd的实例化，遍历，如果实例是SmartInitializingSingleton类型，调用afterSingletonsInstantiated方法。
		// 具体的作用未知？？？
		for (String beanName : beanNames) {
			Object singletonInstance = getSingleton(beanName);
			if (singletonInstance instanceof SmartInitializingSingleton) {
				StartupStep smartInitialize = this.getApplicationStartup().start("spring.beans.smart-initialize")
						.tag("beanName", beanName);
				SmartInitializingSingleton smartSingleton = (SmartInitializingSingleton) singletonInstance;
				if (System.getSecurityManager() != null) {
					AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
						smartSingleton.afterSingletonsInstantiated();
						return null;
					}, getAccessControlContext());
				}
				else {
					smartSingleton.afterSingletonsInstantiated();
				}
				smartInitialize.end();
			}
		}

流程梳理：

1. 遍历所有的bd，对非抽象，单例，非懒加载的类进行实例化
2. 如果是FactoryBean类型的，则实例化FactoryBean,bean名称是&+bean名称。
3. 如果是普通的bean，就直接实例化。

注意：
如果是FactoryBean类型的，通过name得到的实例是该类的getObejct()返回的数据
通过&name，获得的才是FactoryBean的实例。