如何在HK2中将多个接口收集到一个Collection中? [英] How to collect several interfaces into a Collection in HK2?

问题描述

我有我的AbstractBinder，我用相同的接口绑定了几个类.假设我绑定了都实现Animal接口的Fish和Cat.

I have my AbstractBinder and I bind several classes with the same interface. Let's say I bind Fish and Cat which both implement Animal interface.

将它们注入采用Collection<Animal>的bean中最简单/正确的方法是什么?

What is the easiest/proper way of injecting them into a bean which takes Collection<Animal> ?

PS:Spring在@Autowire List<Animal>中具有等效功能，并且集合由Spring创建和填充.

PS: Spring has equivalent in simply @Autowire List<Animal> and the collection is created and populated by Spring.

推荐答案

HK2具有此处文档.您可以获取服务按名称，按

HK2 has IterableProvider<T>, as mentioned here in the documentation. You can get the service by name, by qualifier annotation, or just iterate over them, as it's an Iterable. Just for fun, here is a test.

public class IterableProviderTest {

    public static interface Service {}

    public static class ServiceOne implements Service {}

    @QualAnno
    public static class ServiceTwo implements Service {}

    @Qualifier
    @Target(ElementType.TYPE)
    @Retention(RetentionPolicy.RUNTIME)
    public static @interface QualAnno {
        public static class Instance 
                extends AnnotationLiteral<QualAnno> implements QualAnno {
            public static QualAnno get() {
                return new Instance();
            }
        }
    }

    public class Binder extends AbstractBinder {
        @Override
        protected void configure() {
            bind(ServiceOne.class).to(Service.class).named("one");
            bind(ServiceTwo.class).to(Service.class).qualifiedBy(QualAnno.Instance.get());
        }  
    }

    @Inject
    private IterableProvider<Service> services;

    @Test
    public void test_IterableProvider() {
        ServiceLocator locator = ServiceLocatorUtilities.bind(new Binder());
        locator.inject(IterableProviderTest.this);

        assertEquals(2, services.getSize());

        Service serviceOne = services.named("one").get();
        assertTrue(serviceOne instanceof ServiceOne);

        Service serviceTwo = services.qualifiedWith(QualAnno.Instance.get()).get();
        assertTrue(serviceTwo instanceof ServiceTwo);  
    }
}

---

更新

对于List<Service>(避免使用HK2 InterablProvider)，我唯一想到的就是使用Factory并将IterableProvider注入其中，然后从中返回列表.例如

---

UPDATE

For a List<Service> (to avoid HK2 InterablProvider), the only think I can think of is to use a Factory and inject the IterableProvider into it, and from there return the list. For example

public class Binder extends AbstractBinder {
    @Override
    protected void configure() {
        ...
        bindFactory(ListServiceFactory.class).to(new TypeLiteral<List<Service>>(){});
    }  
}

public static class ListServiceFactory implements Factory<List<Service>> {

    @Inject
    private IterableProvider<Service> services;

    @Override
    public List<Service> provide() {
        return Lists.newArrayList(services);
    }

    @Override
    public void dispose(List<Service> t) {}
}

是的，这需要一些额外的工作.

Yeah it's a little bit of extra work.

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