Component Scan for custom annotation on Interface

Question

I have a component scan configuration as this:

   @Configuration
   @ComponentScan(basePackageClasses = {ITest.class},
                  includeFilters = {@ComponentScan.Filter(type = FilterType.ANNOTATION, value = JdbiRepository.class)})
   public class MyConfig {

   }

Basically I would like to create scan interface which has JdbiRepository annotation

@JdbiRepository
public interface ITest {
  Integer deleteUserSession(String id);
}

And I would like to create proxy implementation of my interfaces. For this purpose I registered a custom SmartInstantiationAwareBeanPostProcessor which is basically creating necessary instances but the configuration above does not scan interfaces which has JdbiRepository annotation.

How can I scan interfaces by custom annotation?

Edit:

It seems that org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider#isCandidateComponent is accepting only concrete classes.

/**
 * Determine whether the given bean definition qualifies as candidate.
 * <p>The default implementation checks whether the class is concrete
 * (i.e. not abstract and not an interface). Can be overridden in subclasses.
 * @param beanDefinition the bean definition to check
 * @return whether the bean definition qualifies as a candidate component
 */
protected boolean isCandidateComponent(AnnotatedBeanDefinition beanDefinition) {
    return (beanDefinition.getMetadata().isConcrete() && beanDefinition.getMetadata().isIndependent());
}

Edit:

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface JdbiRepository {

   /**
    * The value may indicate a suggestion for a logical component name,
    * to be turned into a Spring bean in case of an autodetected component.
    * @return the suggested component name, if any
    */
   String value() default "";
}

How is defined your annotation ? I think you must have Spring's `@Component` annotation on `@JdbiRepository` — Guillaume Darmont, Jul 04 '13 at 20:14
@GuillaumeDarmont it has Component annotation. But I guess that component scanning is working for just concrete classes. — Cemo, Jul 04 '13 at 20:17
Hmm. I did not pay attention to that. But since `isCandidateComponent` can be overriden, you may subclass `ClassPathScanningCandidateComponentProvider`. But I don't know how to integrate it into Spring ApplicationContext loading (self registering ? explicit declaration ?...) — Guillaume Darmont, Jul 04 '13 at 20:32
It will be my last option but before tomorrow I will try another approach as Spring Data project. They are registering components by interfaces. I will give a try, thanks — Cemo, Jul 04 '13 at 20:35

score 6 · Answer 1 · edited May 23 '17 at 11:46

Creating a Dummy implementation seems quite hacky to me and all the steps Cemo mentioned require a lot of effort. But extending ClassPathScanningCandidateComponentProvider is the fastest way:

ClassPathScanningCandidateComponentProvider scanningProvider = new ClassPathScanningCandidateComponentProvider(false) {
    @Override
    protected boolean isCandidateComponent(AnnotatedBeanDefinition beanDefinition) {
        return true;
    }
};

Now you´re also able to scan for Interfaces with (custom) Annotations with Spring - which also works in Spring Boot fat jar environments, where the fast-classpath-scanner (which is mentioned in this so q&a) could have some limitations.

Wait for spring 5.0 :) I had filed an isue and it was scheduled to be resolved in spring 5.0. — Cemo, Jan 06 '17 at 11:46

score 3 · Accepted Answer · answered Jul 08 '13 at 08:08

3

As I said earlier, component scan is working only for concrete classes.

In order to solve my problem I have followed these steps:

Implemented a custom org.springframework.context.annotation.ImportBeanDefinitionRegistrar
Created a custom annotation EnableJdbiRepositories which is importing my custom importer.
Extended ClassPathScanningCandidateComponentProvider in order to scan interfaces too. My custom importer used this class to scan interfaces too.

answered Jul 08 '13 at 08:08

Cemo

5,370
10
50
82

1

You might have registered proxy implementation of `JdbiRepository` annotated interfaces as beans. Could you please guide how did you do it in your implementation of `ImportBeanDefinitionRegistrar`. Could you please share some sample code? – Bilal Mirza Jul 18 '16 at 04:33
1

This is a too old question but the answer here is https://jira.spring.io/browse/SPR-11663 :) It will be resolved in M2. – Cemo Jul 21 '16 at 12:12

score 0 · Answer 3 · edited Mar 04 '15 at 14:53

Instead of scanning an annotated interface, you can create a dummy implementation and annotate it accordingly:

@JdbiRepository
public class DummyTest implements ITest {
  public Integer deleteUserSession(String id) {
    // nothing here, just being dummy
  }
}

Then, scan the dummy implementation basePackageClasses = {DummyTest.class}.

It's a bit of a workaround, but very simple and good enough for test purposes (as seems to be here).

Component Scan for custom annotation on Interface

3 Answers3

Linked