asp.net对URL含有中文参数的转换

protected string urlencode(string url)
        ...{
            byte[] bs = encoding.getencoding("gb2312").getbytes(url);
            stringbuilder sb = new stringbuilder();
            for (int i = 0; i < bs.length; i++)
            ...{
                if (bs[i] < 128)
                    sb.append((char)bs[i]);
                else
                ...{
                    sb.append("%" + bs[i++].tostring("x").padleft(2, '0'));
                    sb.append("%" + bs[i].tostring("x").padleft(2, '0'));
                }
            }
            return sb.tostring();
        }