通过名称使用@ComponentScan进行Spring自动装配，但属性上不使用@Autowired

Question

Just migrating from xml based config to java based config in Spring 4.3.

In xml we had

<beans ... default-autowire="byName">
  <component-scan .../>
  ...
</beans>

On Java classes we have no @Autowired annotations on fields:

@Component
public class MyService {
  private OtherService otherService;
  // +setters
  ....
}

Previously in xml With the default-autowire="byName" autowiring worked pretty well.

Now when moving to JavaConfig I cannot find a way to enable the default autowire mechanism for component scanning.

With autowire by name the wiring works without a @Autowired annotation.

With @Bean(autowire=BY_NAME) i can define a bean to autowire by name, but I would need that mechanism for component scanning. Not to define all beans with @Bean factory method.

Also I try not to add @Autowired annotations to all fields across all classes. Thats just too much to change.

My question now is: How to tell component-scan to autowire found beans by name?

Answer 1

I don't know if I understand what you want to do, but Spring supports @Qualifier and @Resource annotations:

@Resource takes a name attribute, and by default Spring interprets that value as the bean name to be injected. In other words, it follows by-name semantics

Answer 2

One solution would be to update the bean definition with a BeanFactoryPostProcessor to mark all beans to autowire by name like:

public class AutowireScannedByNameBeanPostProcessor implements BeanFactoryPostProcessor {
  @Override
  public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
    Arrays.stream(beanFactory.getBeanDefinitionNames()).forEach(name -> {
      BeanDefinition beanDefinition = beanFactory.getBeanDefinition(name);
      if (beanDefinition instanceof ScannedGenericBeanDefinition) {
        ((ScannedGenericBeanDefinition) beanDefinition).setAutowireMode(AbstractBeanDefinition.AUTOWIRE_BY_NAME);
      }
    });
  }
}

I am still curious if there is a setting in spring that can do this.