using System;

namespace WebApiTest
{
    public class Order
    {
        public int ID { get; set; }

        public DateTime OrderTime { get; set; }
    }
}

using System;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace WebApiTest
{
    /// <summary>
    /// 格式化返回的時(shí)間格式
    /// </summary>
    public class DatetimeJsonConverter : JsonConverter<DateTime>
    {
        public override DateTime Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
        {
            if (reader.TokenType == JsonTokenType.String)
            {
                if (DateTime.TryParse(reader.GetString(), out DateTime date))
                    return date;
            }
            return reader.GetDateTime();
        }

        public override void Write(Utf8JsonWriter writer, DateTime value, JsonSerializerOptions options)
        {
            writer.WriteStringValue(value.ToString("yyyy-MM-dd HH:mm:ss"));
        }
    }
}

public void ConfigureServices(IServiceCollection services)
{
    #region 解決返回時(shí)間帶T的問題
    services.AddControllers().AddJsonOptions(configure =>
    {
        configure.JsonSerializerOptions.Converters.Add(new DatetimeJsonConverter());

    });
    #endregion
}