How to POST a bitmap to a server using Retrofit/Android

Question

I\'m trying to post a bitmap to a server using Android and Retrofit.

Currently I know how to post a file, but I\'d prefer to send a bitmap dir

Answer 1

NOTE: Make this conversion on other thread than Main. RxJava could help to achieve this, or Coroutines

First convert your bitmap to file

//create a file to write bitmap data
File f = new File(context.getCacheDir(), filename);
f.createNewFile();

//Convert bitmap to byte array
Bitmap bitmap = your bitmap;
ByteArrayOutputStream bos = new ByteArrayOutputStream();
bitmap.compress(CompressFormat.JPEG, 0 /*ignored for PNG*/, bos);
byte[] bitmapdata = bos.toByteArray();

//write the bytes in file
FileOutputStream fos = null;
    try {
        fos = new FileOutputStream(f);
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    }
    try {
        fos.write(bitmapdata);
        fos.flush();
        fos.close();
    } catch (IOException e) {
        e.printStackTrace();
    }

After that create a request with Multipart in order to upload your file

RequestBody reqFile = RequestBody.create(MediaType.parse("image/*"), f);
MultipartBody.Part body = MultipartBody.Part.createFormData("upload", f.getName(), reqFile);

Your service call should look like this

interface Service {
    @Multipart
    @POST("/yourEndPoint")
    Call<ResponseBody> postImage(@Part MultipartBody.Part image);
}

And then just call your api

Service service = new Retrofit.Builder().baseUrl("yourBaseUrl").build().create(Service.class);
Call<okhttp3.ResponseBody> req = service.postImage(body);
req.enqueue(new Callback<ResponseBody>() {
    @Override
    public void onResponse(Call<ResponseBody> call, Response<ResponseBody> response) { 
         // Do Something with response
    }

    @Override
    public void onFailure(Call<ResponseBody> call, Throwable t) {
        //failure message
        t.printStackTrace();
    }
});

Answer 2

Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bmp.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray = stream.toByteArray();

you can convert your bitmap into a byte array and then after post this byte array into the server else you can make one tempory file for example

File file = new File(this.getCacheDir(), filename);

file directly uplaod into the server