[GitHub] [dubbo] kylixs commented on issue #8504: 注解与JavaConfig与service group分组写法的迷惑？

[GitBox <gi...@apache.org>]

kylixs commented on issue #8504:
URL: https://github.com/apache/dubbo/issues/8504#issuecomment-900794261


   这里涉及到Spring autowire的实现逻辑，具体可以调试一下代码：  org.springframework.beans.factory.support.DefaultListableBeanFactory#determineAutowireCandidate()
   
   如果不指定primary和priority，最后会尝试匹配beanName和fieldName/dependcyName，即如果fieldName和beanName相同就可以成功注入，如果不相同且存在多个候选bean则会报错。
   
   ```java
   	protected String determineAutowireCandidate(Map<String, Object> candidates, DependencyDescriptor descriptor) {
   		Class<?> requiredType = descriptor.getDependencyType();
   		String primaryCandidate = determinePrimaryCandidate(candidates, requiredType);
   		if (primaryCandidate != null) {
   			return primaryCandidate;
   		}
   		String priorityCandidate = determineHighestPriorityCandidate(candidates, requiredType);
   		if (priorityCandidate != null) {
   			return priorityCandidate;
   		}
   		// Fallback
   		for (Map.Entry<String, Object> entry : candidates.entrySet()) {
   			String candidateName = entry.getKey();
   			Object beanInstance = entry.getValue();
   			if ((beanInstance != null && this.resolvableDependencies.containsValue(beanInstance)) ||
   					matchesBeanName(candidateName, descriptor.getDependencyName())) {
   				return candidateName;
   			}
   		}
   		return null;
   	}
   ```
   
   


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