Simple method to parse an HttpResponse for a Content-Range header and extract the instance length (total size). Great for making partial-content requests.

getInstanceLength.java

/**
 * <p>This method checks an HttpResponse for a Content-Range
 * header and, if present, attempts to parse the instance-length
 * from the header value.</p>
 * <p>{@link http://tools.ietf.org/html/rfc2616#section-14.16}</p>
 * 
 * @param response
 * @return the total number of bytes for the instance, or a negative number if unknown.
 */
public static long getInstanceLength(HttpResponse response) {
    long length = -1;
    if (response != null) {
        Header[] range = response.getHeaders("Content-Range");
        if (range.length > 0) {
            // Get the header value
            String value = range[0].getValue();
            
            // Split the value
            String[] section = value.split("/");
            
            try {
                // Parse for the instance length
                length = Long.parseLong(section[1]);
            } catch (NumberFormatException e) {
                // The server returned an unknown "*" or invalid instance-length
                Log.d(TAG, String.format("The HttpResponse contains an invalid instance-length: %s", value));
            }
        }
    }
    return length;
}