POST Multipart Form Data using Retrofit 2.0 including image

I am highlighting the solution in both 1.9 and 2.0 since it is useful for some

In 1.9, I think the better solution is to save the file to disk and use it as Typed file like:

RetroFit 1.9

(I don't know about your server-side implementation) have an API interface method similar to this

@POST("/en/Api/Results/UploadFile")
void UploadFile(@Part("file") TypedFile file,
                @Part("folder") String folder,
                Callback<Response> callback);

And use it like

TypedFile file = new TypedFile("multipart/form-data",
                                       new File(path));

For RetroFit 2 Use the following method

RetroFit 2.0 ( This was a workaround for an issue in RetroFit 2 which is fixed now, for the correct method refer jimmy0251's answer)

API Interface:

public interface ApiInterface {

    @Multipart
    @POST("/api/Accounts/editaccount")
    Call<User> editUser(@Header("Authorization") String authorization,
                        @Part("file\"; filename=\"pp.png\" ") RequestBody file,
                        @Part("FirstName") RequestBody fname,
                        @Part("Id") RequestBody id);
}

Use it like:

File file = new File(imageUri.getPath());

RequestBody fbody = RequestBody.create(MediaType.parse("image/*"),
                                       file);

RequestBody name = RequestBody.create(MediaType.parse("text/plain"),
                                      firstNameField.getText()
                                                    .toString());

RequestBody id = RequestBody.create(MediaType.parse("text/plain"),
                                    AZUtils.getUserId(this));

Call<User> call = client.editUser(AZUtils.getToken(this),
                                  fbody,
                                  name,
                                  id);

call.enqueue(new Callback<User>() {

    @Override
    public void onResponse(retrofit.Response<User> response,
                           Retrofit retrofit) {

        AZUtils.printObject(response.body());
    }

    @Override
    public void onFailure(Throwable t) {

        t.printStackTrace();
    }
});

There is a correct way of uploading a file with its name with Retrofit 2, without any hack:

Define API interface:

@Multipart
@POST("uploadAttachment")
Call<MyResponse> uploadAttachment(@Part MultipartBody.Part filePart); 
                                   // You can add other parameters too

Upload file like this:

File file = // initialize file here

MultipartBody.Part filePart = MultipartBody.Part.createFormData("file", file.getName(), RequestBody.create(MediaType.parse("image/*"), file));

Call<MyResponse> call = api.uploadAttachment(filePart);

This demonstrates only file uploading, you can also add other parameters in the same method with @Part annotation.

I used Retrofit 2.0 for my register users, send multipart/form File image and text from register account

In my RegisterActivity, use an AsyncTask

//AsyncTask
private class Register extends AsyncTask<String, Void, String> {

    @Override
    protected void onPreExecute() {..}

    @Override
    protected String doInBackground(String... params) {
        new com.tequilasoft.mesasderegalos.dbo.Register().register(txtNombres, selectedImagePath, txtEmail, txtPassword);
        responseMensaje = StaticValues.mensaje ;
        mensajeCodigo = StaticValues.mensajeCodigo;
        return String.valueOf(StaticValues.code);
    }

    @Override
    protected void onPostExecute(String codeResult) {..}

And in my Register.java class is where use Retrofit with synchronous call

import android.util.Log;
import com.tequilasoft.mesasderegalos.interfaces.RegisterService;
import com.tequilasoft.mesasderegalos.utils.StaticValues;
import com.tequilasoft.mesasderegalos.utils.Utilities;
import java.io.File;
import okhttp3.MediaType;
import okhttp3.MultipartBody;
import okhttp3.RequestBody;
import okhttp3.ResponseBody;
import retrofit2.Call; 
import retrofit2.Response;
/**Created by sam on 2/09/16.*/
public class Register {

public void register(String nombres, String selectedImagePath, String email, String password){

    try {
        // create upload service client
        RegisterService service = ServiceGenerator.createUser(RegisterService.class);

        // add another part within the multipart request
        RequestBody requestEmail =
                RequestBody.create(
                        MediaType.parse("multipart/form-data"), email);
        // add another part within the multipart request
        RequestBody requestPassword =
                RequestBody.create(
                        MediaType.parse("multipart/form-data"), password);
        // add another part within the multipart request
        RequestBody requestNombres =
                RequestBody.create(
                        MediaType.parse("multipart/form-data"), nombres);

        MultipartBody.Part imagenPerfil = null;
        if(selectedImagePath!=null){
            File file = new File(selectedImagePath);
            Log.i("Register","Nombre del archivo "+file.getName());
            // create RequestBody instance from file
            RequestBody requestFile =
                    RequestBody.create(MediaType.parse("multipart/form-data"), file);
            // MultipartBody.Part is used to send also the actual file name
            imagenPerfil = MultipartBody.Part.createFormData("imagenPerfil", file.getName(), requestFile);
        }

        // finally, execute the request
        Call<ResponseBody> call = service.registerUser(imagenPerfil, requestEmail,requestPassword,requestNombres);
        Response<ResponseBody> bodyResponse = call.execute();
        StaticValues.code  = bodyResponse.code();
        StaticValues.mensaje  = bodyResponse.message();
        ResponseBody errorBody = bodyResponse.errorBody();
        StaticValues.mensajeCodigo  = errorBody==null
                ?null
                :Utilities.mensajeCodigoDeLaRespuestaJSON(bodyResponse.errorBody().byteStream());
        Log.i("Register","Code "+StaticValues.code);
        Log.i("Register","mensaje "+StaticValues.mensaje);
        Log.i("Register","mensajeCodigo "+StaticValues.mensaje);
    }
    catch (Exception e){
        e.printStackTrace();
    }
}
}

In the interface of RegisterService

public interface RegisterService {
@Multipart
@POST(StaticValues.REGISTER)
Call<ResponseBody> registerUser(@Part MultipartBody.Part image,
                                @Part("email") RequestBody email,
                                @Part("password") RequestBody password,
                                @Part("nombre") RequestBody nombre
);
}

For the Utilities parse ofr InputStream response

public class Utilities {
public static String mensajeCodigoDeLaRespuestaJSON(InputStream inputStream){
    String mensajeCodigo = null;
    try {
        BufferedReader reader = new BufferedReader(
                new InputStreamReader(
                    inputStream, "iso-8859-1"), 8);
        StringBuilder sb = new StringBuilder();
        String line;
        while ((line = reader.readLine()) != null) {
            sb.append(line).append("\n");
        }
        inputStream.close();
        mensajeCodigo = sb.toString();
    } catch (Exception e) {
        Log.e("Buffer Error", "Error converting result " + e.toString());
    }
    return mensajeCodigo;
}
}