protected void populateBean(String beanName, RootBeanDefinition mbd, BeanWrapper bw) {
    // 獲取Bean定義中的屬性值    
    PropertyValues pvs = mbd.getPropertyValues();
    // 如果BeanWrapper為空，則無(wú)法設(shè)置屬性值    
    if (bw == null) {
        if (!pvs.isEmpty()) {
            throw new BeanCreationException(
                    mbd.getResourceDescription(), beanName, "Cannot apply property values to null instance");
        } else {
            // 對(duì)于null實(shí)例，跳過(guò)設(shè)置屬性階段            
            return;
        }
    }
    // 在設(shè)置屬性之前，給InstantiationAwareBeanPostProcessors機(jī)會(huì)修改Bean狀態(tài)    
    // 這可以用于支持字段注入等樣式    
    boolean continueWithPropertyPopulation = true;
    // 如果Bean不是合成的，并且存在InstantiationAwareBeanPostProcessor，執(zhí)行后續(xù)處理    
    if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
        for (BeanPostProcessor bp : getBeanPostProcessors()) {
            if (bp instanceof InstantiationAwareBeanPostProcessor) {
                InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
                if (!ibp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) {
                    continueWithPropertyPopulation = false;
                    break;
                }
            }
        }
    }
    // 如果上述處理后決定不繼續(xù)，則返回    
    if (!continueWithPropertyPopulation) {
        return;
    }
    // 根據(jù)自動(dòng)裝配模式（按名稱(chēng)或類(lèi)型），設(shè)置相關(guān)的屬性值    
    if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME ||
            mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) {
        MutablePropertyValues newPvs = new MutablePropertyValues(pvs);
        // 如果是按名稱(chēng)自動(dòng)裝配，添加相應(yīng)的屬性值        
        if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME) {
            autowireByName(beanName, mbd, bw, newPvs);
        }
        // 如果是按類(lèi)型自動(dòng)裝配，添加相應(yīng)的屬性值        
        if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) {
            autowireByType(beanName, mbd, bw, newPvs);
        }
        pvs = newPvs;
    }
    // 檢查是否需要進(jìn)行依賴(lài)性檢查    
    boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors();
    boolean needsDepCheck = (mbd.getDependencyCheck() != RootBeanDefinition.DEPENDENCY_CHECK_NONE);
    // 如果需要，則進(jìn)行依賴(lài)性檢查    
    if (hasInstAwareBpps || needsDepCheck) {
        PropertyDescriptor[] filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
        if (hasInstAwareBpps) {
            for (BeanPostProcessor bp : getBeanPostProcessors()) {
                if (bp instanceof InstantiationAwareBeanPostProcessor) {
                    InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
                    pvs = ibp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName);
                    if (pvs == null) {
                        return;
                    }
                }
            }
        }
        if (needsDepCheck) {
            checkDependencies(beanName, mbd, filteredPds, pvs);
        }
    }
    // 應(yīng)用屬性值    
    applyPropertyValues(beanName, mbd, bw, pvs);
}

@Override
public PropertyValues postProcessProperties(PropertyValues pvs, Object bean, String beanName) {
    InjectionMetadata metadata = findAutowiringMetadata(beanName, bean.getClass(), pvs);
    try {
        metadata.inject(bean, beanName, pvs);
    }catch (BeanCreationException ex) {
        throw ex;
    }catch (Throwable ex) {
        throw new BeanCreationException(beanName, "Injection of autowired dependencies failed", ex);
    }
    return pvs;
}