How to download file to Internal Storage in Android

AsyncTask.java

//in async task

//usage
// DownloadVideoAsyncTask async = new DownloadVideoAsyncTask(this);
// async.execute("www.site.com/idvideo.mp4");

public class DownloadVideoAsyncTask extends AsyncTask<String, Integer, String> {

    private Context mContext;

    public DownloadVideoAsyncTask(Context context) {
        mContext = context;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();

    }

    @Override
    protected String doInBackground(String... sUrl) {
        InputStream input = null;
        OutputStream output = null;
        HttpURLConnection connection = null;
        try {
            URL url = new URL(sUrl[0]);
            connection = (HttpURLConnection) url.openConnection();
            connection.connect();

            // expect HTTP 200 OK, so we don't mistakenly save error report
            // instead of the file
            if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) {
                return "Server returned HTTP " + connection.getResponseCode()
                        + " " + connection.getResponseMessage();
            }

            // this will be useful to display download percentage
            // might be -1: server did not report the length
            int fileLength = connection.getContentLength();

            // download the file
            input = connection.getInputStream();

//            output = new FileOutputStream("/data/data/com.example.vadym.test1/textfile.txt");
            output = new FileOutputStream(mContext.getFilesDir() + "/file.mp4");

            byte data[] = new byte[4096];
            long total = 0;
            int count;
            while ((count = input.read(data)) != -1) {
                // allow canceling with back button
                if (isCancelled()) {
                    input.close();
                    return null;
                }
                total += count;
                // publishing the progress....
                if (fileLength > 0) // only if total length is known
                    publishProgress((int) (total * 100 / fileLength));
                    output.write(data, 0, count);
            }
        } catch (Exception e) {
            return e.toString();
        } finally {
            try {
                if (output != null)
                    output.close();
                if (input != null)
                    input.close();
            } catch (IOException ignored) {
            }

            if (connection != null)
                connection.disconnect();
        }
        return null;
    }

    @Override
    protected void onProgressUpdate(Integer... values) {
        super.onProgressUpdate(values);
        Log.d("ptg", "onProgressUpdate: " + values[0]);

    }

    @Override
    protected void onPostExecute(String s) {
        super.onPostExecute(s);

    }
}