Spring源码-populateBean填充bean属性

一、bean属性自动装配模式
AutowireCapableBeanFactory

/**
 * 没有自动装配
 */
int AUTOWIRE_NO = 0;

/**
 * 按照名字自动装配
 */
int AUTOWIRE_BY_NAME = 1;

/**
 * 按照类型自动装配
 */
int AUTOWIRE_BY_TYPE = 2;

/**
 * 按照构造器自动装配
 */
int AUTOWIRE_CONSTRUCTOR = 3;

/**
 * 自动检测
 */
@Deprecated
int AUTOWIRE_AUTODETECT = 4;

二、populateBean

protected void populateBean(String beanName, RootBeanDefinition mbd, @Nullable BeanWrapper bw) {
	if (bw == null) {
		if (mbd.hasPropertyValues()) {
			throw new BeanCreationException(
					mbd.getResourceDescription(), beanName, "Cannot apply property values to null instance");
		}
		else {
			// Skip property population phase for null instance.
			return;
		}
	}

	// Give any InstantiationAwareBeanPostProcessors the opportunity to modify the
	// state of the bean before properties are set. This can be used, for example,

	// 调用InstantiationAwareBeanPostProcessor的postProcessAfterInstantiation，一般用于设置属性
	if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
		for (InstantiationAwareBeanPostProcessor bp : getBeanPostProcessorCache().instantiationAware) {
			if (!bp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) {
				return;
			}
		}
	}

	PropertyValues pvs = (mbd.hasPropertyValues() ? mbd.getPropertyValues() : null);

	int resolvedAutowireMode = mbd.getResolvedAutowireMode(); // 获取装配模式
	if (resolvedAutowireMode == AUTOWIRE_BY_NAME || resolvedAutowireMode == AUTOWIRE_BY_TYPE) { // 按照名字或类型装配
		MutablePropertyValues newPvs = new MutablePropertyValues(pvs);
		// Add property values based on autowire by name if applicable.
		if (resolvedAutowireMode == AUTOWIRE_BY_NAME) {
			autowireByName(beanName, mbd, bw, newPvs);
		}
		// Add property values based on autowire by type if applicable.
		if (resolvedAutowireMode == AUTOWIRE_BY_TYPE) {
			autowireByType(beanName, mbd, bw, newPvs);
		}
		pvs = newPvs;
	}

	boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors(); //工厂是否拥有InstiationAwareBeanPostProcessor
	boolean needsDepCheck = (mbd.getDependencyCheck() != AbstractBeanDefinition.DEPENDENCY_CHECK_NONE); //是否需要依赖检查

	PropertyDescriptor[] filteredPds = null;
	if (hasInstAwareBpps) {
		if (pvs == null) {
			pvs = mbd.getPropertyValues();
		}
		for (InstantiationAwareBeanPostProcessor bp : getBeanPostProcessorCache().instantiationAware) {
			PropertyValues pvsToUse = bp.postProcessProperties(pvs, bw.getWrappedInstance(), beanName);
			if (pvsToUse == null) {
				if (filteredPds == null) {
					filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
				}
				pvsToUse = bp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName);
				if (pvsToUse == null) {
					return;
				}
			}
			pvs = pvsToUse;
		}
	}
	if (needsDepCheck) {
		if (filteredPds == null) {
			filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
		}
		checkDependencies(beanName, mbd, filteredPds, pvs);
	}

	if (pvs != null) {
		applyPropertyValues(beanName, mbd, bw, pvs);
	}
}

1. 调用InstantiationAwareBeanPostProcessor的postProcessAfterInstantiation，一般用于设置属性。

2. 获取自动装配模式，如果是按照名字或类型装配，则自动装配属性后添加到MutablePropertyValues

3. 判断工厂是否拥有InstiationAwareBeanPostProcessor，如果有则工厂将给定的属性值应用到给定Bean之前，对它们进行后处理，即postProcessProperties，如果pvs为null且filteredPds为空过滤出需要依赖检查的属性，即filterPropertyDescriptorsForDependencyCheck，调用postProcessPropertyValues后置处理，一般进行检查是否所有依赖项都满足或者替换要应用的属性值

4. 如果需要检查依赖，如果filteredPds为null则调用filterPropertyDescriptorsForDependencyCheck过滤要忽略检查的依赖属性，调用checkDependencies检查依赖。

5. 将属性应用到bean