在构造函数或者 全局开始的时候调用这个

public BossApiController()        {            JsonMediaTypeFormatter jsonFormatter = GlobalConfiguration.Configuration.Formatters.JsonFormatter;            JsonSerializerSettings jSettings = new Newtonsoft.Json.JsonSerializerSettings()            {                Formatting = Formatting.Indented,                DateTimeZoneHandling = DateTimeZoneHandling.Utc            };            jSettings.Converters.Add(new MyDateTimeConvertor());            jsonFormatter.SerializerSettings = jSettings;        }

相关类有：

public class MyDateTimeConvertor : DateTimeConverterBase    {        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)        {            return DateTime.Parse(reader.Value.ToString());        }        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)        {            writer.WriteValue(((DateTime)value).ToString("yyyy-MM-dd HH:mm:ss"));        }    }