C# 时间格式化 RFC3399

# 秒
DateTime.Now.ToString("yyyy-MM-dd'T'HH:mm:ss'Z'")

# 毫秒
DateTime.Now.ToString("yyyy-MM-dd'T'HH:mm:ss.fff'Z'")

var timeFormat = new IsoDateTimeConverter();
timeFormat.DateTimeFormat = "yyyy-MM-dd'T'HH:mm:ss'Z'";
JsonConvert.SerializeObject(new { CreateTime = DateTime.Now }, Formatting.Indented, timeFormat);

var setting = new JsonSerializerSettings()
{
    DateFormatString = "yyyy-MM-dd'T'HH:mm:ss'Z'"
};
JsonConvert.SerializeObject(new { CreateTime = DateTime.Now }, setting);