Question

在我的Android项目中，我使用以下Retrofit ApiModule来获取一个 API端点。请注意，我使用Dagger注入依赖项。

@Module(
        complete = false,
        library = true
)
public final class ApiModule {

    public static final String PRODUCTS_BASE_URL = "https://products.com";

    @Provides
    @Singleton
    Endpoint provideEndpoint() {
        return Endpoints.newFixedEndpoint(PRODUCTS_BASE_URL);
    }

    @Provides
    @Singleton
    ObjectMapper provideObjectMapper() {
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.setPropertyNamingStrategy(
            PropertyNamingStrategy.CAMEL_CASE_TO_LOWER_CASE_WITH_UNDERSCORES);
        return objectMapper;
    }

    @Provides
    @Singleton
    RestAdapter provideRestAdapter(
        Endpoint endpoint, ObjectMapper objectMapper) {
        return new RestAdapter.Builder()
                .setLogLevel(RestAdapter.LogLevel.NONE)
                .setEndpoint(endpoint)
                .setConverter(new JacksonConverter(objectMapper))
                .build();
    }

    @Provides
    @Singleton
    ProductsService provideProductsService(RestAdapter restAdapter) {
        return restAdapter.create(ProductsService.class);
    }

}

现在，我想与之沟通另一个API （例如"http://subsidiaries.com"）。是否可以在重用ApiModule和ObjectMapper时扩展给定的RestAdapter？或者我不应该延长它？我已经尝试复制模块了。但这涉及到我必须复制Endpoint，ObjectMapper和... RestAdapter有一个私有构造函数 - 所以我不能。

Answer 1

我猜你可以使用Named注释：

@Module(
        complete = false,
        library = true
)
public final class ApiModule {

    public static final String PRODUCTS_BASE_URL = "https://products.com";
    public static final String SUBSIDIARIES_BASE_URL = "https://subsidiaries.com";

    public static final String PRODUCTS = "products";
    public static final String SUBSIDIARIES = "subsidiaries";

    @Provides
    @Singleton
    @Named(PRODUCTS)
    Endpoint provideProductsEndpoint() {
        return Endpoints.newFixedEndpoint(PRODUCTS_BASE_URL);
    }

    @Provides
    @Singleton
    @Named(SUBSIDIARIES)
    Endpoint provideSubsidiariesEndpoint() {
        return Endpoints.newFixedEndpoint(SUBSIDIARIES_BASE_URL);
    }

    @Provides
    @Singleton
    ObjectMapper provideObjectMapper() {
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.setPropertyNamingStrategy(
            PropertyNamingStrategy.CAMEL_CASE_TO_LOWER_CASE_WITH_UNDERSCORES);
        return objectMapper;
    }

    @Provides
    @Singleton
    @Named(PRODUCTS)
    RestAdapter provideProductsRestAdapter(@Named(PRODUCTS) Endpoint endpoint, ObjectMapper objectMapper) {
        return newRestAdapterBuilder(objectMapper)
                .setEndpoint(endpoint)
                .build();
    }

    @Provides
    @Singleton
    @Named(SUBSIDIARIES)
    RestAdapter provideSubsidiariesRestAdapter(@Named(SUBSIDIARIES) Endpoint endpoint, ObjectMapper objectMapper) {
        return newRestAdapterBuilder(objectMapper)
                .setEndpoint(endpoint)
                .build();
    }

    @Provides
    @Singleton
    @Named(PRODUCTS)
    ProductsService provideProductsService(@Named(PRODUCTS) RestAdapter restAdapter) {
        return restAdapter.create(ProductsService.class);
    }

    @Provides
    @Singleton
    @Named(SUBSIDIARIES)
    ProductsService provideSubsidiariesService(@Named(SUBSIDIARIES) RestAdapter restAdapter) {
        return restAdapter.create(ProductsService.class);
    }

    private RestAdapter.Builder newRestAdapterBuilder(ObjectMapper objectMapper) {
        return new RestAdapter.Builder()
                       .setLogLevel(RestAdapter.LogLevel.NONE)
                       .setConverter(new JacksonConverter(objectMapper));
    }
}

现在，在您注射ProductsService的任何地方，都需要使用@Named(PRODUCTS)或@Named(SUBSIDIARIES)注释依赖项，具体取决于您需要的变体。当然，除了@Named注释，您还可以创建自己的自定义注释并使用它们。请参阅“限定符”下的here。

要稍微展平您的模块，您可以将RestAdapter的创建移动到provide*Service()方法中，并删除provide*RestAdapter()方法。当然，除非你需要RestAdapters作为模块之外的依赖项。

如何使用Retrofit解决多个API端点？

1 个答案: