I need to upload a large generated pdf file to the server and show uploading progress to the user. But the problem is the percentage I got from OutputStream is not the real progress because after 100% progress of OutputStream, still cannot get response code from the server (need to wait for more)
Please help me with this problem. Thank you.
** For more information: the total uploading time is 15 minutes but the progress percentage finish in a second.
class UploadPdf extends AsyncTask<String, Integer, String> {
    private Activity activity;
    private String orderId = "";
    private String filenamepdf = "";
    private String filenamezip = "";
    private int dpi = 640;
    public ImageCreator mImageCreator;
    public UploadPdf(Activity activity) {
        this.activity = activity;
    }
    @Override
    protected String doInBackground(String... strings) {
        orderId = strings[0];
        filenamepdf = orderId + ".pdf";
        String uploadStatus = uploadFileToServer();
        return uploadStatus;
    }
    @Override
    protected void onProgressUpdate(Integer... progress) {
        //Update progress
        updateProgress(progress[0]);
    }
    @Override
    protected void onPostExecute(String result) {
        //Show result
        try {
            JSONObject obj = new JSONObject(result);
            if(obj.getString("status").equals("success")) {
                uploadSuccess();
            } else {
                errorContainer.setVisibility(View.VISIBLE);
            }
        } catch (Exception ex) {
            errorContainer.setVisibility(View.VISIBLE);
        }
    }
    private String uploadFileToServer() {
        Log.d(LOGTAG, "uploadFileToServer");
        String urlString = Constants.API_BASE_URL + Constants.API_CREATE_UPLOAD_FILE;
        String response = null;
        String attachmentName = "attachment";
        String attachmentFileName = "attachment";
        String crlf = "\r\n";
        String twoHyphens = "--";
        String boundary = "*****";
        try {
            File file = new File(filenamepdf);
            MultipartUtility multipart = new MultipartUtility(urlString, "UTF-8", getApplicationContext());
            multipart.addFormField("order_id", orderId);
            multipart.addFilePart("album_image_path", file);
            List<String> responseReturn = multipart.finish();
            Log.e(LOGTAG, "SERVER REPLIED:");
            response = "";
            for (String line : responseReturn) {
                Log.e(LOGTAG, "Upload Files Response:::" + line);
                response += line;
            }
        } catch (Exception ex) {
            Log.e(LOGTAG, "Failed:" + ex.getMessage());
        }
        Log.e(LOGTAG, "Response:" + response);
        return response;
    }
    public class MultipartUtility {
        private final String LOGTAG = "MultipartUtility";
        private final String boundary;
        private static final String LINE_FEED = "\r\n";
        private HttpURLConnection httpConn;
        private String charset;
        private OutputStream outputStream;
        private PrintWriter writer;
        Context context;
        /**
         * This constructor initializes a new HTTP POST request with content type
         * is set to multipart/form-data
         *
         * @param requestURL
         * @param charset
         * @throws IOException
         */
        public MultipartUtility(String requestURL, String charset, Context context)
                throws IOException {
            this.charset = charset;
            this.context = context;
            // creates a unique boundary based on time stamp
            boundary = "===" + System.currentTimeMillis() + "===";
            URL url = new URL(requestURL);
            httpConn = (HttpURLConnection) url.openConnection();
            httpConn.setUseCaches(false);
            httpConn.setDoOutput(true);    // indicates POST method
            httpConn.setDoInput(true);
            httpConn.setRequestProperty("Content-Type",
                    "multipart/form-data; boundary=" + boundary);
            outputStream = httpConn.getOutputStream();
            writer = new PrintWriter(new OutputStreamWriter(outputStream, charset),
                    true);
        }
        /**
         * Adds a form field to the request
         *
         * @param name  field name
         * @param value field value
         */
        public void addFormField(String name, String value) {
            Log.d(LOGTAG, "name: " + name + ", value: " + value);
            writer.append("--" + boundary).append(LINE_FEED);
            writer.append("Content-Disposition: form-data; name=\"" + name + "\"")
                    .append(LINE_FEED);
            writer.append("Content-Type: text/plain; charset=" + charset).append(
                    LINE_FEED);
            writer.append(LINE_FEED);
            writer.append(value).append(LINE_FEED);
            writer.flush();
        }
        /**
         * Adds a upload file section to the request
         *
         * @param fieldName  name attribute in <input type="file" name="..." />
         * @param uploadFile a File to be uploaded
         * @throws IOException
         */
        public void addFilePart(String fieldName, File uploadFile) throws IOException {
            String fileName = uploadFile.getName();
            Log.d(LOGTAG, fieldName);
            writer.append("--" + boundary).append(LINE_FEED);
            writer.append(
                    "Content-Disposition: form-data; name=\"" + fieldName
                            + "\"; filename=\"" + fileName + "\"")
                    .append(LINE_FEED);
            writer.append(
                    "Content-Type: "
                            + URLConnection.guessContentTypeFromName(fileName))
                    .append(LINE_FEED);
            writer.append("Content-Transfer-Encoding: binary").append(LINE_FEED);
            writer.append(LINE_FEED);
            writer.flush();
            FileInputStream inputStream = new FileInputStream(uploadFile);
            byte[] bytes = new byte[(int) uploadFile.length()];
            int byteLength = bytes.length;
            byte[] buffer = new byte[4096];
            int bytesRead = -1;
            int sendByte = 0;
            while ((bytesRead = inputStream.read(buffer)) != -1) {
                outputStream.write(buffer, 0, bytesRead);
                sendByte += bytesRead;
                int progress = (int)(sendByte / (float) byteLength * 100);
                Log.d(LOGTAG, "bytesRead: " + bytesRead + ", byteLength: " + byteLength + ", progress: " + progress);
                publishProgress(progress);
            }
            outputStream.flush();
            Log.d(LOGTAG, "Read byte finish");
            outputStream.close();
            Log.d(LOGTAG, "Close output stream");
            inputStream.close();
            Log.d(LOGTAG, "Close input stream");
            writer.append(LINE_FEED);
            writer.flush();
            Log.d(LOGTAG, "Writer flushed");
        }
        public void addHeaderField(String name, String value) {
            writer.append(name + ": " + value).append(LINE_FEED);
            writer.flush();
        }
        public List<String> finish() throws IOException {
            Log.d(LOGTAG, "Finishing");
            List<String> response = new ArrayList<String>();
            writer.append(LINE_FEED).flush();
            Log.d(LOGTAG, "Line feed flushed");
            writer.append("--" + boundary + "--").append(LINE_FEED);
            Log.d(LOGTAG, "Last line flushed");
            writer.close();
            Log.d(LOGTAG, "Writer closed");
            // checks server's status code first
            int status = httpConn.getResponseCode();
            Log.d(LOGTAG, "Server returned status: " + status);
            if (status == HttpURLConnection.HTTP_OK) {
                BufferedReader reader = new BufferedReader(new InputStreamReader(
                        httpConn.getInputStream()));
                String line = null;
                while ((line = reader.readLine()) != null) {
                    response.add(line);
                }
                reader.close();
                httpConn.disconnect();
            } else {
                throw new IOException("Server returned non-OK status: " + status);
            }
            return response;
        }
    }
}