TokenAttachingInterceptor for OkHttpClient

TokenAttachingInterceptor.java

import android.support.annotation.NonNull;
import com.jakewharton.rxrelay2.BehaviorRelay;
import java.io.IOException;
import javax.inject.Inject;
import javax.inject.Singleton;
import okhttp3.Interceptor;
import okhttp3.Request;
import okhttp3.Response;
import timber.log.Timber;

@Singleton public class TokenAttachingInterceptor implements Interceptor {

  private static final String X_AUTH_TOKEN = "X-AuthToken";
  private static final String NO_AUTHENTICATION = "No-Authentication";

  private final @TokenRelay BehaviorRelay<String> tokenRelay;

  @Inject public TokenAttachingInterceptor(@TokenRelay BehaviorRelay<String> tokenRelay) {
    this.tokenRelay = tokenRelay;
  }

  @Override public Response intercept(@NonNull Chain chain) throws IOException {
    Request request = chain.request();
    if (request.header(NO_AUTHENTICATION) == null) {
      String token = tokenRelay.getValue();
      if (token == null) {
        return chain.proceed(request);
      }
      request = request.newBuilder().addHeader(X_AUTH_TOKEN, token).build();
    } else {
      request = request.newBuilder().removeHeader(NO_AUTHENTICATION).build();
    }
    return chain.proceed(request);
  }
}

This is a basic OkHttpClient interceptor which takes a BehaviorRelay as an input parameter. On each outbound network request, the intercepter will use the latest token within the relay and attach it as an authentication header. This allows you to avoid having to add extra parameters to Retrofit method definitions 💪

Found this in an old project of mine and going with this approach in Jarvis