@SuppressWarnings("unchecked")
    @Nullable
    private <T> NamedBeanHolder<T> resolveNamedBean(
            ResolvableType requiredType, @Nullable Object[] args, boolean nonUniqueAsNull) throws BeansException {

        Assert.notNull(requiredType, "Required type must not be null");
        String[] candidateNames = getBeanNamesForType(requiredType);

        if (candidateNames.length > 1) {
            List<String> autowireCandidates = new ArrayList<>(candidateNames.length);
            for (String beanName : candidateNames) {
                if (!containsBeanDefinition(beanName) || getBeanDefinition(beanName).isAutowireCandidate()) {
                    autowireCandidates.add(beanName);
                }
            }
            if (!autowireCandidates.isEmpty()) {
                candidateNames = StringUtils.toStringArray(autowireCandidates);
            }
        }

        if (candidateNames.length == 1) {
            String beanName = candidateNames[0];
            return new NamedBeanHolder<>(beanName, (T) getBean(beanName, requiredType.toClass(), args));
        }
        else if (candidateNames.length > 1) {
            Map<String, Object> candidates = new LinkedHashMap<>(candidateNames.length);
            for (String beanName : candidateNames) {
                if (containsSingleton(beanName) && args == null) {
                    Object beanInstance = getBean(beanName);
                    candidates.put(beanName, (beanInstance instanceof NullBean ? null : beanInstance));
                }
                else {
                    candidates.put(beanName, getType(beanName));
                }
            }
            String candidateName = determinePrimaryCandidate(candidates, requiredType.toClass());
            if (candidateName == null) {
                candidateName = determineHighestPriorityCandidate(candidates, requiredType.toClass());
            }
            if (candidateName != null) {
                Object beanInstance = candidates.get(candidateName);
                if (beanInstance == null || beanInstance instanceof Class) {
                    beanInstance = getBean(candidateName, requiredType.toClass(), args);
                }
                return new NamedBeanHolder<>(candidateName, (T) beanInstance);
            }
            if (!nonUniqueAsNull) {
                throw new NoUniqueBeanDefinitionException(requiredType, candidates.keySet());
            }
        }

        return null;
    }

    @SuppressWarnings("unchecked")
    @Nullable
    private <T> NamedBeanHolder<T> resolveNamedBean(
            ResolvableType requiredType, @Nullable Object[] args, boolean nonUniqueAsNull) throws BeansException {

        Assert.notNull(requiredType, "Required type must not be null");
        // 该方法根据传入的Class类型获取BeanName，因为有接口有多个实现类情况，所以这里返回是String数组。
        // 调用getBean方法传入的type为com.javaedge.FactoryBeanService类型，但没有在Spring容器中注入FactoryBeanService类型的Bean
        // 所以讲道理在这里应该获取不到beanName，事实是这样吗？看对getBeanNamesForType的分析
        String[] candidateNames = getBeanNamesForType(requiredType);
        // 有多个BeanName，则挑最合适的
        if (candidateNames.length > 1) {
            List<String> autowireCandidates = new ArrayList<>(candidateNames.length);
            for (String beanName : candidateNames) {
                if (!containsBeanDefinition(beanName) || getBeanDefinition(beanName).isAutowireCandidate()) {
                    autowireCandidates.add(beanName);
                }
            }
            if (!autowireCandidates.isEmpty()) {
                candidateNames = StringUtils.toStringArray(autowireCandidates);
            }
        }

        // 如果只有一个BeanName，调用getBean获取Bean实例放到NamedBeanHolder
        // todo
        if (candidateNames.length == 1) {
            String beanName = candidateNames[0];
            return new NamedBeanHolder<>(beanName, (T) getBean(beanName, requiredType.toClass(), args));
        }
        // 经过挑选后，如果合适的BeanName还是多个
        else if (candidateNames.length > 1) {
            Map<String, Object> candidates = new LinkedHashMap<>(candidateNames.length);
            for (String beanName : candidateNames) {
                // 看看是不是已经创建过的单例Bean
                if (containsSingleton(beanName) && args == null) {
                    Object beanInstance = getBean(beanName);
                    candidates.put(beanName, (beanInstance instanceof NullBean ? null : beanInstance));
                }
                else {
                    // 调用getType继续获取Bean实例
                    candidates.put(beanName, getType(beanName));
                }
            }
            // 有多个Bean实例，则取带有Primary注解或者带有Primary信息的
            String candidateName = determinePrimaryCandidate(candidates, requiredType.toClass());
            if (candidateName == null) {
                // 如果没有Primary注解或者Primary相关的信息，则取优先级高的Bean
                candidateName = determineHighestPriorityCandidate(candidates, requiredType.toClass());
            }
            if (candidateName != null) {
                Object beanInstance = candidates.get(candidateName);
                // Class类型的话 继续调用getBean获取Bean实例
                if (beanInstance == null || beanInstance instanceof Class) {
                    beanInstance = getBean(candidateName, requiredType.toClass(), args);
                }
                return new NamedBeanHolder<>(candidateName, (T) beanInstance);
            }
            if (!nonUniqueAsNull) {
                // 都没获取到，抛出异常
                throw new NoUniqueBeanDefinitionException(requiredType, candidates.keySet());
            }
        }

        return null;
    }