Android : File Download over http request failed

In My android Application i have a list of song.User can download any of song from it. But my problem is when i download a file using http request it return content length = 0 or -1 so i can not download file. When i use same url in browser then song downloaded completely. My code to download a song file is -

  URL url = new URL(mUrl);
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                connection.setRequestMethod("GET");
                connection.setDoOutput(true);
                connection.setConnectTimeout(TimeOut);
                connection.setReadTimeout(TimeOut);
                connection.connect();
                int lenghtOfFile = connection.getContentLength();

and file length is either 0 or -1. What the problem in my code.

Thanks in advance.