带有命名绑定的 Guice 多重绑定

Question

我有一堆处理器。有些具有相同的对象类型但具有不同的配置。我想创建一组处理器，但选择哪个处理器应放入哪个组中。是否有办法使用多重绑定来做到这一点？

public class PostProcessorModule extends AbstractModule {

    public static final String TYPE_A = "TypeA";
    public static final String TYPE_B = "TypeB";

    @Override
    protected void configure() {
        Multibinder<PostProcessor> typeASet =
            Multibinder.newSetBinder(binder(), PostProcessor.class, Names.named("TypeASet"));
        typeASet.addBinding().to(RandomizationPostProcessor.class);  // Only want Type A 
here
        typeASet.addBinding().to(SecondPostProcessor.class);

        Multibinder<PostProcessor> typeBSet =
            Multibinder.newSetBinder(binder(), PostProcessor.class, Names.named("TypeBSet"));
        typeASet.addBinding().to(RandomizationPostProcessor.class);  // Only want Type B 
here
        typeASet.addBinding().to(SecondPostProcessor.class);
    }


    @Provides
    @Singleton
    @Named(TYPE_A)
    public RandomizationPostProcessor getRandomizationPostProcessorA() {

        return RandomizationPostProcessor.builder()
                   .toRandomize(3)
                   .build();
    }

    @Provides
    @Singleton
    @Named(TYPE_B)
    public RandomizationPostProcessor getRandomizationPostProcessorB() {

        return RandomizationPostProcessor.builder()
                   .toRandomize(10)
                   .build();
    }

    @Provides
    @Singleton
    public SecondPostProcessor getSecondPostProcessor() {

        return new SecondPostProcessor();
    }
}

public class Test {
    @Inject
    @Named("TypeASet")
    private final Set<PostProcessor> setA;
    
    @Inject
    @Named("TypeBSet")
    private final Set<PostProcessor> setB;

    public void doSomething() {
        ...
    }
}

RandomizationPostProcessor

和

SecondPostProcessor

实现

PostProcessor

。

多重绑定支持吗？我看不到任何像

annotatedWith

或普通

bind()

函数中具有的类似函数。编写另一个函数是创建自定义集的唯一方法吗？

Answer 1

当然，您可以

addBinding

到特定键：

typeASet.addBinding().to(Key.get(RandomizationPostProcessor.class, Names.named(TYPE_A))
typeBSet.addBinding().to(Key.get(RandomizationPostProcessor.class, Names.named(TYPE_B))