c#里的字符串转16进制ASCII

c#里的字符串转16进制ASCII 就像这样的

郑州  %d6%a3%d6%dd&

三门峡  %c8%fd%c3%c5%cf%bf

public staticstring GetUrlEncode(string trueUrl)
        {
            return System.Web.HttpUtility.UrlEncode(trueUrl, System.Text.Encoding.GetEncoding("GB2312"));
        }
        publicstatic string GetUrlDecode(string trueUrl)
        {
            return System.Web.HttpUtility.UrlEncode(trueUrl, System.Text.Encoding.GetEncoding("GB2312"));
        }