Question

I have a Android application and I want to show a progress bar for downloaded weather data. I will show a weather forecast for around 5 places. The problem is when I want to get the Content-Length from the response header. The log always shows me -1(it means that the field is not set in the URLConnection variable).

This is the code I’m using:

private class DownloadWeatherData extends AsyncTask<String, Integer, String> {
        @Override
        protected String doInBackground(String... sUrl) {
            try {
                URL url = new URL("http://www.google.com/ig/api?weather=NY&hl=en&oe=utf-8");
                URLConnection connection = url.openConnection();

                int dataLenght = connection.getContentLength();
                Log.d("ANDRO_ASYNC", "Data lenght: " + dataLenght);

                InputStream input = new BufferedInputStream(url.openStream());

                byte data[] = new byte[1024];
                long total = 0;
                int count;

                while ((count = input.read(data)) != -1) {
                    total += count;
                    Log.d("ANDRO_ASYNC", ""+(int)((count)));
                }
                input.close();
            } catch (Exception e) {
            }
            return null;
        }
    }

What can I do? Or is there another way to show progress of the downloaded data?

Answer 1

Very often pages and other files are not delivered with a Content-Length header (sent as “chunks” of data). In that case normally browsers do not show a percentage, but a perpetual animation bar (“// // // // //“).

Of course you can always fake it when knowing the average response time of the site and transfer slowness of client.