方式是将字符串分隔，先，分隔，再用：分隔。最后再 .ToDictionary 转换为字典。然后就大家都会获取了
string str = "{\"fcode\":\"10\",\"fno\":\"009999\",\"fmemo\":\"009999-4\"}";
Dictionary<string, object> dd = str.Trim(new char[] { '{', '}' }).Split(',').ToDictionary(s => s.Split(':')[0].Trim('"'), s => (object)s.Split(':')[1].Trim('"'));
Console.WriteLine(dd["fcode"]);