Question

我有很多具有接口Foo的对象。所以我有很多Foo的提供者，没有问题。

我的问题是我有一个需要foo集合的对象（All the Foo）。请考虑以下事项：

@Module
@AppScope
public class AppModule {
    //OTHER PROVIDERS MY FOO'S DEPEND ON OMITTED 
    @Provides
    AaFoo provideAaFoo(){
        return new AaFoo();
    }

    @Provides 
    BbFoo provideBbFoo(){
        return new BbFoo();
    }

    @Provides
    CcFoo providesCcFoo(Something something) {
        return new CcFoo(something);
    }

    //EVEN MORE KINDS OF FOO's...

    //Now I need to provide a thing that holds all Foo's
    //TODO: This pattern is horribly ugly!
    @Provides
    FooManager provideFooManager(
            AaFoo aa,
            BbFoo bb,
            CcFoo cc,
            ...) {//each time I make a foo I have to add; mention it here
        FooManager fooService = new FooManager();
        fooService.addFoo(aa);
        fooService.addFoo(bb);
        fooService.addFoo(cc);
        fooService.addFoo(dd); 
        ... //and I need to put it here, how nice it would be if this were a collection...
        return fooService;
    }
}

有没有办法我可以让匕首将所有foo聚合成一个集合，这样我就可以将该集合传递给我的provideRouteService方法？那样，当我添加更多foo时，一切正常吗？

Answer 1

啊，答案是在Multibindings（https://google.github.io/dagger//multibindings.html）中，非常简单：

简单地转换上述内容：

将@IntoSet添加到我的每个Foo提供商。
让他们都返回Foo而不是子类型
让FooProvider采用Set

示例：

@Module
@AppScope
public class AppModule {
    //OTHER PROVIDERS MY FOO'S DEPEND ON OMITTED 
    @Provides
    @IntoSet
    Foo provideAaFoo(){
        return new AaFoo();
    }

    @Provides 
    @IntoSet
    Foo provideBbFoo(){
        return new BbFoo();
    }

    @Provides
    @IntoSet
    Foo providesCcFoo(Something something) {
        return new CcFoo(something);
    }

    //EVEN MORE KINDS OF FOO's...

    //Now I need to provide a thing that holds all Foo's
    //TODO: This pattern isn't ugly any more!
    @Provides
    FooManager provideFooManager(
            Set<Foo> foos) {
        return new FooManager(foos);
    }
}

还使用@Inject注释了FooManager的构造函数。更清楚了！

Dagger2将相同基类型的提供者聚合到Array或Collection中？

1 个答案: