simple HttpURLConnection POST file multipart/form-data from android to google blobstore

use okhttp and use following snippet (taken from recipes)

adjust the header values according to what your server expects.

private static final String IMGUR_CLIENT_ID = "...";
private static final MediaType MEDIA_TYPE_PNG = MediaType.parse("image/png");

private final OkHttpClient client = new OkHttpClient();

public void run() throws Exception {
// Use the imgur image upload API as documented at https://api.imgur.com/endpoints/image
    RequestBody requestBody = new MultipartBuilder()
    .type(MultipartBuilder.FORM)
    .addPart(
        Headers.of("Content-Disposition", "form-data; name=\"title\""),
        RequestBody.create(null, "Square Logo"))
    .addPart(
        Headers.of("Content-Disposition", "form-data; name=\"image\""),
        RequestBody.create(MEDIA_TYPE_PNG, new File("website/static/logo-square.png")))
    .build();

Request request = new Request.Builder()
    .header("Authorization", "Client-ID " + IMGUR_CLIENT_ID)
    .url("https://api.imgur.com/3/image")
    .post(requestBody)
    .build();

Response response = client.newCall(request).execute();
if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

System.out.println(response.body().string());
}