// org.springframework.beans.factory.support.DefaultListableBeanFactory#resolveDependency
public Object resolveDependency(
    DependencyDescriptor descriptor, String requestingBeanName, 
    Set<String> autowiredBeanNames, TypeConverter typeConverter) {
    
    // 1. 嘗試按類型匹配所有候選 Bean
    Map<String, Object> matchingBeans = findAutowireCandidates(beanName, type, descriptor);
    
    // 2. 如果候選 Bean 超過(guò) 1 個(gè)，檢查是否有 @Primary 或 @Qualifier
    if (matchingBeans.size() > 1) {
        Object primaryCandidate = determinePrimaryCandidate(matchingBeans, descriptor.getDependencyType());
        if (primaryCandidate != null) {
            return primaryCandidate;
        }
        // 如果沒(méi)有 @Primary，檢查 @Qualifier
        Object qualifierCandidate = determineQualifierCandidate(matchingBeans, descriptor);
        if (qualifierCandidate != null) {
            return qualifierCandidate;
        }
        // 仍無(wú)法解決則拋出異常
        throw new NoUniqueBeanDefinitionException(type, matchingBeans.keySet());
    }
    // ...
}

// org.springframework.context.annotation.CommonAnnotationBeanPostProcessor#autowireResource
protected void autowireResource(
    ResourceElement element, Object bean, String requestingBeanName) {
    
    String name = element.name; // @Resource 的 name 屬性
    Object resource;
    
    // 1. 嘗試按名稱注入
    if (resource != null) {
        resource = getResource(element, requestingBeanName);
    } else {
        // 2. 名稱未指定時(shí)，回退到按類型注入（可能仍會(huì)失?。?
        resource = findResourceByType(element.lookupType);
    }
    
    if (resource == null) {
        throw new NoSuchBeanDefinitionException(...);
    }
    // ...
}

// 方式 1：@Autowired + @Qualifier
@Autowired
@Qualifier("nzxxServiceImpl1")
private NzxxService nzxxService;

// 方式 2：@Resource
@Resource(name = "nzxxServiceImpl1")
private NzxxService nzxxService;

@Service
@Primary // 標(biāo)記為默認(rèn)實(shí)現(xiàn)
public class NzxxServiceImpl1 implements NzxxService { ... }

@Service("nzxxServiceImpl2")
public class NzxxServiceImpl2 implements NzxxService { ... }

// 無(wú)需 @Qualifier，自動(dòng)注入 NzxxServiceImpl1
@Autowired
private NzxxService nzxxService;

@Service
@Profile("dev") // 僅在 dev 環(huán)境激活
public class NzxxServiceDevImpl implements NzxxService { ... }

@Service
@Profile("prod") // 僅在 prod 環(huán)境激活
public class NzxxServiceProdImpl implements NzxxService { ... }

@Autowired
private ObjectProvider<NzxxService> nzxxServiceProvider;

public void someMethod() {
    // 運(yùn)行時(shí)決定使用哪個(gè)實(shí)現(xiàn)
    NzxxService service = nzxxServiceProvider.getObject("nzxxServiceImpl1");
    service.doSomething();
}

logging.level.org.springframework.beans.factory=DEBUG