字母排序：

public static String getParamSrc(Dictionary<string, string> paramsMap)
        {
            var vDic = (from objDic in paramsMap orderby objDic.Key ascending select objDic);
            StringBuilder str = new StringBuilder();
            foreach (KeyValuePair<string, string> kv in vDic)
            {
                string pkey = kv.Key;
                string pvalue = kv.Value;
                str.Append(pkey + "=" + pvalue + "&");
            }