CODEWITHSUNDEEP
javaspring
ticktock
ticktock

Reputation: 1703

Get List of bean types from application context

I'm interested in getting a list of beans from the Spring ApplicationContext. In particular, these are Ordered beans

 @Component
  @Order(value=2)

And I'm in some legacy code that is not Spring enabled, so I've manufactured a method to get the ApplicationContext. For spring beans, I know I can do something like:

@Bean
public SomeType someType(List<OtherType> otherTypes) {
    SomeType someType = new SomeType(otherTypes);
    return someType;
}

But the ApplicationContext only provides a method getBeansOfType which returns an unordered map. I've tried getBeanNames(type) but that also returns things unordered.

The only thing I can think of is to create a dummy class that just contains the List, create a bean for that dummy class and retrieve the ordered list:

public class DumbOtherTypeCollection {
    private final List<OtherType) otherTypes;
    public DumbOtherTypeCollection(List<OtherType) otherTypes) {
        this.otherTypes = otherTypes;
    }

    List<OtherType> getOrderedOtherTypes() { return otherTypes; }
}

@Bean 
DumbOtherTypeCollection wasteOfTimeReally(List<OtherType otherTypes) {
    return new DumbOtherTypeCollection(otherTypes);
}

....

applicationContext.getBean(DumbOtherTypeCollection.class).getOrderedOtherTypes();

Just wish I could do better.

Upvotes: 3

Views: 5974

Answers (1)

Alex Ciocan
Alex Ciocan

Reputation: 2322

Spring can autowire all beans of a type into list. In addition to this if your beans are annotated with the @Ordered or if the beans implement the Ordered interface, then this list will have all the beans ordered.(Spring reference)

@Autowired docs:

In case of a Collection or Map dependency type, the container will autowire all beans matching the declared value type.

@Autowired
List<MyType> beans;

EDIT: Ordering using the built-in OrderComparator

For your external context call, in order to have your beans prioritized by their order you could take advandate of the built-in comparator:

org.springframework.core.annotation.AnnotationAwareOrderComparator(new ArrayList(applicationContext.getBeansOfType(...).values()));

Or 

Collections.sort((List<Object>)applicationContext.getBeansOfType(...).values(),org.springframework.core.annotation.AnnotationAwareOrderComparator.INSTANCE);

Upvotes: 7

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