C# ASCII码排序

public static string GetSignContent(IDictionary<string, string> parameters)
{
// 第一步：把字典按Key的字母顺序排序
IDictionary<string, string> sortedParams = new SortedDictionary<string, string>(parameters);
IEnumerator<KeyValuePair<string, string>> dem = sortedParams.GetEnumerator();

// 第二步：把所有参数名和参数值串在一起
StringBuilder query = new StringBuilder("");
while (dem.MoveNext())
{
string key = dem.Current.Key;
string value = dem.Current.Value;
if (!string.IsNullOrEmpty(key) && !string.IsNullOrEmpty(value))
{
query.Append(key).Append("=").Append(value).Append("&");
}
}
string content = query.ToString().Substring(0, query.Length - 1);

return content;
}