Newtonsoft.Json 转换DateTime类型为字符串时，串内部会有一个T。解决方案

使用Newtonsoft.Json 转换DateTime类型时，若使用标准转换，则字符串内会有一个T（虽然再转换成DateTime没有问题）。

若要转换成DateTime没有T，可以加上特性：

public class TestClass 
    {
        public TestClass()
        {
            Dt1 = Dt2 = new DateTime(1900, 1, 1, 0, 0, 0);
        }

        [JsonConverter(typeof(TcDateTimeConverter))]
        public DateTime Dt1 { get; set; }

        public DateTime Dt2 { get; set; }
    }



 /// <summary>
    /// DateTime Json序列化格式：yyyy-MM-dd HH:mm:ss
    /// </summary>
    public class TcFullDateTimeConverter : DateTimeConverterBase
    {
        private static IsoDateTimeConverter dtConverter = new IsoDateTimeConverter { DateTimeFormat = "yyyy-MM-dd HH:mm:ss" };

        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        {
            return dtConverter.ReadJson(reader, objectType, ConvertHelper.ToDateTime(existingValue), serializer);
        }

        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
        {
            dtConverter.WriteJson(writer, ConvertHelper.ToDateTime(value), serializer);
        }
    }

    /// <summary>
    /// DateTime Json序列化格式：yyyy-MM-dd HH:mm
    /// </summary>
    public class TcDateTimeConverter : DateTimeConverterBase
    {
        private static IsoDateTimeConverter dtConverter = new IsoDateTimeConverter { DateTimeFormat = "yyyy-MM-dd HH:mm" };

        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        {
            return dtConverter.ReadJson(reader, objectType, ConvertHelper.ToDateTime(existingValue), serializer);
        }

        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
        {
            dtConverter.WriteJson(writer, ConvertHelper.ToDateTime(value), serializer);
        }
    }

    /// <summary>
    /// DateTime Json序列化格式：yyyy-MM-dd
    /// </summary>
    public class TcDateConverter : DateTimeConverterBase
    {
        private static IsoDateTimeConverter dtConverter = new IsoDateTimeConverter { DateTimeFormat = "yyyy-MM-dd" };

        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        {
            return dtConverter.ReadJson(reader, objectType, ConvertHelper.ToDateTime(existingValue), serializer);
        }

        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
        {
            dtConverter.WriteJson(writer, ConvertHelper.ToDateTime(value), serializer);
        }
    }

    /// <summary>
    /// DateTime Json序列化格式：HH:mm
    /// </summary>
    public class TcTimeConverter : DateTimeConverterBase
    {
        private static IsoDateTimeConverter dtConverter = new IsoDateTimeConverter { DateTimeFormat = "HH:mm" };

        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        {
            return dtConverter.ReadJson(reader, objectType, ConvertHelper.ToDateTime(existingValue), serializer);
        }

        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
        {
            dtConverter.WriteJson(writer, ConvertHelper.ToDateTime(value), serializer);
        }
    }

另外，若某字段如上加上TcDateTimeConverter，再转换为带TcDateTimeConverter特性或者不带该特性的标准DateTime，都没有问题。