NetCore3 System.Text.Json 的使用 控制台

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

  services.AddControllers(x=>
            {
                //x.Filters.Add();
            }) 
              .AddJsonOptions(options=>
              {
                  //options.JsonSerializerOptions.PropertyNamingPolicy = System.Text.Json.JsonNamingPolicy.CamelCase;
                  options.JsonSerializerOptions.PropertyNamingPolicy = null; //响应驼峰命名
                  options.JsonSerializerOptions.Encoder = System.Text.Encodings.Web.JavaScriptEncoder.UnsafeRelaxedJsonEscaping;//中文乱码
                  options.JsonSerializerOptions.Converters.Add(new Common.SystemTextJsonConvert.DateTimeConverter());//应时间格式
                  options.JsonSerializerOptions.Converters.Add(new Common.SystemTextJsonConvert.DateTimeNullableConverter()); //应时间格式
              }).SetCompatibilityVersion(CompatibilityVersion.Version_3_0);

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

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

        public class DateTimeNullableConverter : JsonConverter<DateTime?>
        {
            public override DateTime? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
            {
                return 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"));
            }
        }
    }

 public static class JsonOpt
    {
        public static JsonSerializerOptions UnicodeRangesAll
        {
            get { return  DefaultOptions(); }
        }

        public static JsonSerializerOptions IgnoreNullValues
        {
            get 
            { 
                JsonSerializerOptions options = DefaultOptions();
                options.IgnoreNullValues = true;
                return options;
            }
        }

        public static JsonSerializerOptions DefaultOptions(string dateTimeFormat = "yyyy-MM-dd HH:mm:ss")
        {
            JsonSerializerOptions Options = new JsonSerializerOptions() { PropertyNamingPolicy = null, WriteIndented = true, Encoder = System.Text.Encodings.Web.JavaScriptEncoder.Create(UnicodeRanges.All) };
            Options.Converters.Add(new DateTimeConverterUsingDateTimeParse(dateTimeFormat));
            return Options;
        }
    }

var options = new JsonSerializerOptions();
            options.Encoder = System.Text.Encodings.Web.JavaScriptEncoder.Create(UnicodeRanges.All);
            var json = JsonSerializer.Serialize(new { title = "代码改变世界" }, options);