Retrofit File Upload:

Config class:

public class RetroConfig {

    public static Retrofit retrofit(){

        OkHttpClient client = new OkHttpClient();
        client.retryOnConnectionFailure();
        client.cache();

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("http://bestvote.in/privilege/")
                .addConverterFactory(GsonConverterFactory.create())
                .client(client)
                .build();
        return retrofit;
    }
}

Create Api Interface:

import com.squareup.okhttp.RequestBody;
import com.squareup.okhttp.Response;

import org.json.JSONObject;

import okhttp3.ResponseBody;
import retrofit.Call;
import retrofit.http.Field;
import retrofit.http.FormUrlEncoded;
import retrofit.http.GET;
import retrofit.http.Multipart;
import retrofit.http.POST;
import retrofit.http.Part;
import retrofit.http.Path;
import retrofit.http.Query;
public interface ApiInterface {

    @Multipart
    @POST("insertpost.php")
    Call<CommonResponse> submitForm(@Part("description") RequestBody desc, @Part("audio\"; filename=\".mp3\" ") RequestBody audio,
                              @Part("image\"; filename=\".jpg\" ") RequestBody photo,
                              @Part("late") RequestBody lat, @Part("long") RequestBody lon);

    @GET("allpost.php")
    Call<SellerResponse> getSellerAds();
}

Call Api Post method:

import retrofit.Call;
import retrofit.Callback;
import retrofit.Retrofit;
import com.squareup.okhttp.MediaType;
import com.squareup.okhttp.RequestBody;
import com.squareup.okhttp.Response;

private void submitForm() {
        String desc = details.getText().toString();

        if (!desc.equals("") && imagePath!=null && audioPath!=null) {
            RequestBody descBody = RequestBody.create(MediaType.parse("text/plain"), desc);
            RequestBody latBody = RequestBody.create(MediaType.parse("text/plain"), latFinal);
            RequestBody lonBody = RequestBody.create(MediaType.parse("text/plain"), lngFinal);
            RequestBody imageBody = RequestBody.create(MediaType.parse("multipart/form-data"), new File(imagePath));
            RequestBody audioBody = RequestBody.create(MediaType.parse("multipart/form-data"), new File(audioPath));
            //RequestBody videoBody = RequestBody.create(MediaType.parse("multipart/form-data"), new File(videoPath));

            final ProgressDialog dialog = new ProgressDialog(SellerActivity.this);
            dialog.setMessage("Uploading...");
            dialog.setCancelable(false);
            dialog.show();

            Call<CommonResponse> call = RetroConfig.client().submitForm(descBody, audioBody, imageBody, latBody, lonBody);
            call.enqueue(new Callback<CommonResponse>() {
                @Override
                public void onResponse(retrofit.Response<CommonResponse> response, Retrofit retrofit) {
                    dialog.cancel();
                    if (response.body() != null) {
                        CommonResponse response1 = response.body();
                        if(response1.getResponse().equals("success")){
                            Toast.makeText(SellerActivity.this, "Upload Ads successfully..", Toast.LENGTH_SHORT).show();
                            startActivity(new Intent(SellerActivity.this, SellerAds.class));
                            finish();
                        }
                    }
                }

                @Override
                public void onFailure(Throwable t) {
                    Log.e("submitError", t.getLocalizedMessage());
                    dialog.cancel();
                }
            });
        } else {
            Utils.showDialog(SellerActivity.this, "Please select All files");
        }
    }   

CallGet Method:

RetroConfig.client().getSellerAds().enqueue(new Callback<SellerResponse>() {
            @Override
            public void onResponse(Response<SellerResponse> response, Retrofit retrofit) {
                SellerResponse sr = response.body();
                String status = sr.getResponse();
                if(status.equals("success")){
                    List<SAds> sAdses = sr.getSellerAds();
                    rv.setAdapter(new SellerAdsAdapter(SellerAds.this, sAdses));
                }
            }

            @Override
            public void onFailure(Throwable t) {
                Log.e("error", t.getLocalizedMessage());
            }
        });