Spring autowire by name with @ComponentScan but without @Autowired on property

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?

this [answer](https://stackoverflow.com/questions/24883987/how-to-configure-component-scan-by-annotation-only-in-spring) , isnt what you looking for? Also this allows you to import conf from a custom spring-beans.xml , in case that you cannot retype the same configuration in java class — AntJavaDev, Apr 10 '18 at 11:35
I would encourage you to write `@Autowired`. If you literally mean it when you write "all fields across all classes" there is something terribly wrong with your design. Declaring that relevant fields are autowired will distinguish them from those that are not and increase readability. — Jan Larsen, Apr 10 '18 at 11:51
haha, terribly wrong is the right term. We are talking about a code base that lives since ~8 years. No class has @Autowired annotations. And we are not going to add those ;) with the previous xml definition is was possible to set default autowire mechanism, but with java it seems not to be possible in an easy way — serprime, Apr 11 '18 at 14:30

score 0 · Answer 1 · answered Apr 10 '18 at 14:00

0

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

answered Apr 10 '18 at 14:00

dgarceran

177
4
14

I try not to add @Resource/@Autowired annotations on the fields/setters of the properties that should be wired. – serprime Apr 11 '18 at 13:24

score 0 · Accepted Answer · answered Apr 11 '18 at 13:27

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.

Spring autowire by name with @ComponentScan but without @Autowired on property

2 Answers2