How to get the upload progress

Question

I use doInBackGround and AsyncTask method to show progress as below:

class UploadFile extends AsyncTask<String, String, String> {
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        showDialog(DIALOG_DOWNLOAD_PROGRESS);
    }

    @Override
    protected String doInBackground(String... aurl) {
        upload(ActionUrl, uploadFile, savepath, newName);
        return null;
    }

    protected void onProgressUpdate(String... progress) {
        mProgressDialog.setProgress(Integer.parseInt(progress[0]));
    }

    @Override
    protected void onPostExecute(String unused) {
        dismissDialog(DIALOG_DOWNLOAD_PROGRESS);
    }
}

The upload(ActionUrl, uploadFile, savepath, newName); method is such as this. And below code:

@Override
protected Dialog onCreateDialog(int id) {
    switch (id) {
        case DIALOG_DOWNLOAD_PROGRESS: //we set this to 0
            mProgressDialog = new ProgressDialog(this);
            mProgressDialog.setMessage("Downloading file...");
            mProgressDialog.setIndeterminate(false);
            mProgressDialog.setMax(100);
            mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            mProgressDialog.setCancelable(true);
            mProgressDialog.show();
            return mProgressDialog;
        default:
            return null;
    }
}

And below to call:

private ProgressDialog mProgressDialog;
public static final int DIALOG_DOWNLOAD_PROGRESS = 0;
new UploadFile().execute("test");

But the Progress Dialog always show 0%, and never update. How to modify to update it?