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Set dynamic base url using Retrofit 2.0 and Dagger 2

I'm trying to perform a login action using Retrofit 2.0 using Dagger 2

Here's how I set up Retrofit dependency

@Provides
@Singleton
Retrofit provideRetrofit(Gson gson, OkHttpClient client) {
    Retrofit retrofit = new Retrofit.Builder()
                            .addConverterFactory(GsonConverterFactory.create(gson)
                            .client(client)
                            .baseUrl(application.getUrl())
                            .build();
    return retrofit;     
}

Here's the API interface.

interface LoginAPI {
   @GET(relative_path)
   Call<Boolean> logMe();
}

I have three different base urls users can log into. So I can't set a static url while setting up Retrofit dependency. I created a setUrl() and getUrl() methods on Application class. Upon user login, I set the url onto Application before invoking the API call.

I use lazy injection for retrofit like this

Lazy<Retrofit> retrofit

That way, Dagger injects dependency only when I can call

retrofit.get()

This part works well. I got the url set to retrofit dependency. However, the problem arises when the user types in a wrong base url (say, mywifi.domain.com), understands it's the wrong one and changes it(say to mydata.domain.com). Since Dagger already created the dependency for retrofit, it won't do again. So I have to reopen the app and type in the correct url.

I read different posts for setting up dynamic urls on Retrofit using Dagger. Nothing really worked out well in my case. Do I miss anything?

like image 653
Renjith Avatar asked Apr 08 '16 11:04

Renjith


People also ask

How do you dynamically change base URL in retrofit?

For latest Retrofit library, you can simply use singleton instance and change it with retrofitInstance. newBuilder(). baseUrl(newUrl) . No need to create another instance.

How do I set up a retrofit URL?

Actually, it only requires you to add a single String parameter annotated with @Url in your endpoint definition. Short code says more than thousand words :) As you can see, you'll leave the @GET annotation without the endpoint url and add the @Url to the method itself.

Can you use multiple baseUrl in retrofit?

Yes, you can create two different Service instances.


2 Answers

Support for this use-case was removed in Retrofit2. The recommendation is to use an OkHttp interceptor instead.

HostSelectionInterceptor made by swankjesse

import java.io.IOException;
import okhttp3.HttpUrl;
import okhttp3.Interceptor;
import okhttp3.OkHttpClient;
import okhttp3.Request;

/** An interceptor that allows runtime changes to the URL hostname. */
public final class HostSelectionInterceptor implements Interceptor {
  private volatile String host;

  public void setHost(String host) {
    this.host = host;
  }

  @Override public okhttp3.Response intercept(Chain chain) throws IOException {
    Request request = chain.request();
    String host = this.host;
    if (host != null) {
      //HttpUrl newUrl = request.url().newBuilder()
      //    .host(host)
      //    .build();
      HttpUrl newUrl = HttpUrl.parse(host);
      request = request.newBuilder()
          .url(newUrl)
          .build();
    }
    return chain.proceed(request);
  }

  public static void main(String[] args) throws Exception {
    HostSelectionInterceptor interceptor = new HostSelectionInterceptor();

    OkHttpClient okHttpClient = new OkHttpClient.Builder()
        .addInterceptor(interceptor)
        .build();

    Request request = new Request.Builder()
        .url("http://www.coca-cola.com/robots.txt")
        .build();

    okhttp3.Call call1 = okHttpClient.newCall(request);
    okhttp3.Response response1 = call1.execute();
    System.out.println("RESPONSE FROM: " + response1.request().url());
    System.out.println(response1.body().string());

    interceptor.setHost("www.pepsi.com");

    okhttp3.Call call2 = okHttpClient.newCall(request);
    okhttp3.Response response2 = call2.execute();
    System.out.println("RESPONSE FROM: " + response2.request().url());
    System.out.println(response2.body().string());
  }
}

Or you can either replace your Retrofit instance (and possibly store the instance in a RetrofitHolder in which you can modify the instance itself, and provide the holder through Dagger)...

public class RetrofitHolder {
   Retrofit retrofit;

   //getter, setter
}

Or re-use your current Retrofit instance and hack the new URL in with reflection, because screw the rules. Retrofit has a baseUrl parameter which is private final, therefore you can access it only with reflection.

Field field = Retrofit.class.getDeclaredField("baseUrl");
field.setAccessible(true);
okhttp3.HttpUrl newHttpUrl = HttpUrl.parse(newUrl);
field.set(retrofit, newHttpUrl);
like image 92
EpicPandaForce Avatar answered Oct 22 '22 02:10

EpicPandaForce


Retrofit2 library comes with a @Url annotation. You can override baseUrl like this:

API interface:

public interface UserService {  
    @GET
    public Call<ResponseBody> profilePicture(@Url String url);
}

And call the API like this:

Retrofit retrofit = Retrofit.Builder()  
    .baseUrl("https://your.api.url/");
    .build();

UserService service = retrofit.create(UserService.class);  
service.profilePicture("https://s3.amazon.com/profile-picture/path");

For more details refer to this link: https://futurestud.io/tutorials/retrofit-2-how-to-use-dynamic-urls-for-requests

like image 66
Jaydev Mehta Avatar answered Oct 22 '22 03:10

Jaydev Mehta