netcore3 api 时间格式化

    public class DateTimeNullConverter : JsonConverter<DateTime?>
    {
        public override DateTime? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
            => string.IsNullOrEmpty(reader.GetString()) ? default(DateTime?) : DateTime.Parse(reader.GetString());

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

    public class DateTimeConverter : JsonConverter<DateTime>
    {
        public override DateTime Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
            => DateTime.Parse(reader.GetString());

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

　　

 services.AddControllers().AddJsonOptions(options =>
            {
                options.JsonSerializerOptions.Converters.Add(new DateTimeConverter());
                options.JsonSerializerOptions.Converters.Add(new DateTimeNullConverter());
            });