path = ConfigurationManager.AppSettings["fileDownloaderPath"];

context.Response.Clear();
context.Response.ContentType = "application/json";
string isfile = "";
isfile = context.Request.QueryString["isFile"];

if (isfile.Equals("true"))
{
    string fileName = "";
    fileName = context.Request.QueryString["fileName"];

    string sha = "";
    sha = context.Request.QueryString["sha"];

    string fullPath = path + removeInvalidChar(fileName);
    log.Debug(fullPath);
    StreamReader sr = File.OpenText(fullPath);

    string wsSha = GetSha(sr.ReadToEnd());
    sr.Close();
    context.Response.AddHeader("Content-Disposition", "attachment; filename=" + wsSha);

    if (wsSha.Equals(sha))
    {
        context.Response.Write("");
        context.Response.Flush();
    }
    else
    {
        context.Response.WriteFile(fullPath);
        context.Response.Flush();
    }
}

new DownloadFileAndAnalyzeItAsyncTask(a).executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, a.getFileName());

@Override
    protected Void doInBackground(String... params) {
        Realm realm = null;
        newSha = null;
        try {
            realm = Realm.getDefaultInstance();

            publishProgress(5);
            String url = String.format("%sFileDownloader.ashx?filename=%s.txt&isFile=true&cache=%s", RuntimeHelper._baseWebServiceIP, params[0], UUID.randomUUID());
            OkHttpClient client = new OkHttpClient.Builder()
                    .connectTimeout(30, TimeUnit.SECONDS)
                    .writeTimeout(60, TimeUnit.SECONDS)
                    .readTimeout(30, TimeUnit.SECONDS)
                    .retryOnConnectionFailure(true)
                    .build();
            publishProgress(10);
            Request request = new Request.Builder().url(url)
                    .addHeader("Content-Type", "application/json")
                    .addHeader("Connection", "close")
                    .build();
            publishProgress(15);
            Response response = client.newCall(request).execute();
            publishProgress(20);

            ResponseBody responseBody = response.body();
            publishProgress(25);
            try {
                String myHeader = response.header("Contenwt-Disposition");
                if (myHeader != null) {
                    int position = myHeader.indexOf("filename=");
                    position += "filename=".length();
                    newSha = myHeader.substring(position);
                }
            } catch (Exception ex) {
                newSha = null;
            }
            if (responseBody == null) {
                return null;
            }

            InputStream is = responseBody.byteStream();

            OutputStream outputStream = new FileOutputStream(new File(SyncActivity.this.getFilesDir(), fileName + ".txt"));

            BufferedReader reader = new BufferedReader(new InputStreamReader(is));
            StringBuilder result;
            String line = reader.readLine();
            result = new StringBuilder(line);
            while ((line = reader.readLine()) != null) {
                result.append(line);
            }
            Log.d(TAG, result.toString());
            response.close();

            OutputStreamWriter writer = new OutputStreamWriter(outputStream);
            writer.write(result.toString());
            writer.flush();
            writer.close();

            outputStream.flush();
            outputStream.close();
            response.close();

Response response = client.newCall(request).execute();