Changing baseUrl dynamically using retrofit & dagger2

Question

I'm using retrofit & Dagger2 for my application.I want to change the baseUrl of an application dynamically based on the what user selects in the Spinner.

After spending couple of hours on internet i came to conclusion that it is possible to change the baseUrl dynamically.

The Dependency Injection looks like this:

APiModule

  @Module
public class ApiModule {

 String mBaseUrl;

    public ApiModule(String mBaseUrl) {
        this.mBaseUrl = mBaseUrl;
    }

@Provides
    @Singleton
    OkHttpClient provideOkhttpClient(Cache cache) {
        OkHttpClient.Builder client = new OkHttpClient.Builder();           
        HttpLoggingInterceptor logging = new HttpLoggingInterceptor();
        // set your desired log level
        logging.setLevel(HttpLoggingInterceptor.Level.BODY);
        client.addInterceptor(logging);
        client.cache(cache);
        return client.build();   
    }

    @Provides
    @Singleton
    Retrofit provideRetrofit(OkHttpClient okHttpClient) {
        return new Retrofit.Builder()
                .addConverterFactory(GsonConverterFactory.create())
                .baseUrl(mBaseUrl)
                .client(okHttpClient)
                .build();
    }
}

I have created one extra class as per the reference from internet

HostSelectionInterceptor.java

import java.io.IOException;
import javax.inject.Singleton;
import dagger.Module;
import dagger.Provides;
import okhttp3.HttpUrl;
import okhttp3.Interceptor;
import okhttp3.Request;
/** An interceptor that allows runtime changes to the URL hostname. */
@Module(includes = {ApiModule.class})
public final class HostSelectionInterceptor implements Interceptor {
    private volatile String host;

    @Provides
    @Singleton
    public String setHost(String host) {
        this.host = host;
        return this.host;
    }

    public String getHost() {
        return host;
    }

    @Provides
    @Singleton
    @Override
    public okhttp3.Response intercept(Chain chain) {
        Request request = chain.request();
        String  host    = getHost();
        if (host != null) {
           /* HttpUrl newUrl = request.url().newBuilder()
                    .host(host)
                    .build();*/
            HttpUrl newUrl = HttpUrl.parse(host);
            request = request.newBuilder()
                    .url(newUrl)
                    .build();
        }
        try {
            return chain.proceed(request);
        } catch (IOException e) {
            e.printStackTrace();
        }

        return null;
    }
}

Now, my question is how i can use HostSelectionInterceptor to change my baseUrl on changing the Spinner.

Possible duplicate of [Dagger + Retrofit dynamic URL](https://stackoverflow.com/questions/36769923/dagger-retrofit-dynamic-url) — David Medenjak, Aug 18 '17 at 08:27

score 3 · Answer 1 · answered Aug 18 '17 at 09:53

You can use @Named (or custom annotations that are annotated with @Qualifier) Add the annotations like the following:

@Singleton
@Provides
@Named("picture")
Retrofit providePictureRetrofit(GsonConverterFactory gsonConverterFactory, RxJavaCallAdapterFactory rxJavaCallAdapterFactory) {
    return retrofit = new Retrofit.Builder()
            .baseUrl(MarsWeatherWidget.PICTURE_URL) // one url
            .build();
}



@Singleton
@Provides
@Named("weather")
Retrofit provideWeatherRetrofit(GsonConverterFactory gsonConverterFactory, RxJavaCallAdapterFactory rxJavaCallAdapterFactory) {
    return retrofit = new Retrofit.Builder()
            .baseUrl(MarsWeatherWidget.WEATHER_URL) // other url
            .build();
}

Injecting the qualified version

When you have your module providing the qualified types, you just need to also add the qualifier where you need the dependency.

MyPictureService provideService(@Named("picture") Retrofit retrofit) {
    // ...
}

score 1 · Answer 2 · answered Aug 18 '17 at 08:07

Request.Builder.url - is a request URL. So it's everything that is added to Base_URL.

To dynamically change the base url, you have to recreate retrofit object.

Checkout the Mock Server I've been working on: https://github.com/macieknajbar/MockServer/blob/master/app/src/main/java/com/example/mockserver/rest/server/MockServer.kt

Run tests and make changes for your own use (to replace base url, not only responses).

Changing baseUrl dynamically using retrofit & dagger2

2 Answers2