HTTP Utility using retrofit2 and okhttp

ActivityMain.java

private void prepareNetwork() {
  File httpCacheDirectory = new File(getCacheDir(), "responses");
  int cacheSize = 10 * 1024 * 1024; // 10 MiB
  Cache cache = new Cache(httpCacheDirectory, cacheSize);

  OkHttpClient client = new OkHttpClient.Builder()
    .cache(cache)
    .addNetworkInterceptor(REWRITE_CACHE_CONTROL_INTERCEPTOR)
    .build();

  Retrofit signUp = new Retrofit.Builder()
    .client(client)
    .baseUrl(getString(R.string.base_url))
    .addConverterFactory(GsonConverterFactory.create())
    .build();

  api = signUp.create(Api.class);
}    

private void getData() {
  Call<ResponseBody> call = api.getData(user.getUid());

  call.enqueue(new Callback<ResponseBody>() {
    @Override
    public void onResponse(Call<ResponseBody> call, final Response<ResponseBody> response) {
        String response = response.body().string();
      } catch (Exception e) {
        showError();
      }
    }

    @Override
    public void onFailure(Call<List<DashboardModel>> call, Throwable t) {
      t.printStackTrace();
    }
  });
}

private final Interceptor REWRITE_CACHE_CONTROL_INTERCEPTOR = new Interceptor() {
  @Override
  public okhttp3.Response intercept(Chain chain) throws IOException {
    okhttp3.Response originalResponse = chain.proceed(chain.request());
    if (Network.hasConnectivity(Dashboard.this, true)) {
      int maxAge = 60; // read from cache for 1 minute
      return originalResponse.newBuilder()
              .header("Cache-Control", "public, max-age=" + maxAge)
              .build();
    } else {
      int maxStale = 60 * 60 * 24 * 28; // tolerate 4-weeks stale
      return originalResponse.newBuilder()
              .header("Cache-Control", "public, only-if-cached, max-stale=" + maxStale)
              .build();
    }
  }
};

private void startDataService() {
  prepareNetwork();
  getData();
}

Api.java

import okhttp3.ResponseBody;
import retrofit2.Call;
import retrofit2.http.GET;
import retrofit2.http.Query;

public interface Api {
  
  @GET("data")
  Call<ResponseBody> getData(@Query("id") String id);
  
}

build.gradle

...

dependencies {
  ...
  implementation 'com.squareup.retrofit2:retrofit:2.3.0'
  implementation 'com.squareup.retrofit2:converter-gson:2.3.0'
  ...
}

...