Xtykutl

I am using Dagger 2 + Retrofit to implement my interfaces which sends/receives data to/from my web service

I am referring Philippe BOISNEY's AppModule.java as below

private static String BASE_URL = "https://api.github.com/";



@Provides

Gson provideGson() { return new GsonBuilder().create(); }



@Provides

Retrofit provideRetrofit(Gson gson) {

    Retrofit retrofit = new Retrofit.Builder()

            .addConverterFactory(GsonConverterFactory.create(gson))

            .baseUrl(BASE_URL)

            .build();

    return retrofit;

}

However I have a question that what if I have multiple hosts of my web services, such as Production, Staging and Development?

I already setup those different hosts connected to Build Config in my AndroidManifest.xml, but I don't have an idea how to read meta-data in AppModule, in order to replace BASE_URL with corresponding build config

Please kindly advice me, thank you

You can define in build.gradle several flavor types like dev, prod and stage and for each flavor define build config variable

productFlavors {

    dev {

        buildConfigField "String", "SERVER_URL", ""your dev url""

    }

    stage {

        buildConfigField "String", "SERVER_URL", ""your stage url""

    }

    prod {

        buildConfigField "String", "SERVER_URL", ""your prod url""

    }

}

And after that use it

private static String BASE_URL = BuildConfig.SERVER_URL;

If you like to provide it dynamically using dagger, you can do it in that way

@Module

public class AppModule {

    @Named("server_url")

    @Provides

    String provideServerUrl() {

        return "https://api.github.com/";

    }



    @Provides

    Retrofit provideRetrofit(Gson gson, @Named("server_url") String url) {

        Retrofit retrofit = new Retrofit.Builder()

            .addConverterFactory(GsonConverterFactory.create(gson))

            .baseUrl(url)

            .build();

        return retrofit;

    }

}

Another way of dynamically providing server url using dagger - using builder. For example,

@Component(AppModule.class)

interface AppComponent {

    @Component.Builder

    interface Builder {

        @BindsInstance

        Builder serverUrl(@Named("server_url") String url);



        AppComponent build();

    }

}



@Module

public class AppModule {

    @Provides

    Retrofit provideRetrofit(Gson gson, @Named("server_url") String url) {

        Retrofit retrofit = new Retrofit.Builder()

            .addConverterFactory(GsonConverterFactory.create(gson))

            .baseUrl(url)

            .build();

        return retrofit;

    }

}



DaggerAppComponent.Builder()

    .appModule(new AppModule())

    .serverUrl("https://api.github.com/")

    .build();

I give up reading corresponding host from meta-data in AndroidManefist, instead, I switch to another approach by referring @ConstOrVar's suggestion

Here is my app/build.gradle, I have 2 flavors which describes my staging and production host respectively

productFlavors {

    production {

        buildConfigField("String", "SERVER_HOST", ""myproductionost.com"")

    }

    staging {

        buildConfigField("String", "SERVER_HOST", ""mystaginghost.com"")

    }

}

Then here is my codes in my AppModule.java

@Module

public class AppModule {



    @Provides

    Retrofit provideRetrofit(Gson gson) {

        Retrofit retrofit = new Retrofit.Builder()

                .addConverterFactory(GsonConverterFactory.create(gson)) 

                .baseUrl("https://" + BuildConfig.SERVER_HOST)

                .build();

        return retrofit;

    }

}

By doing so, Retrofit will tells which host of webservice it shall talk with based on BuildVariant automatically