public static String parseOptionalStringAttr(String line, Pattern pattern) {
        if (pattern == null)
            return null;
        Matcher matcher = pattern.matcher(line);
        return matcher.find() ? matcher.group(1) : null;
    }
parse network M3U8 file.

@param videoUrl
@return
@throws IOException
library/src/main/java/com/jeffmony/downloader/m3u8/M3U8Utils.java