System.Text.Json 自定义Converter实现时间转换

Posted 2021-02-28 createwell

Newtonsoft.Json与System.Text.Json区别

在 Newtonsoft.Json中可以使用例如

.AddJsonOptions(options =>
                {
                    options.SerializerSettings.DateFormatString = "yyyy-MM-dd HH:mm:ss";
                })

方式设置接收/序列化时间格式，但在.net core 3.1中System.Text.Json是没有自带方式进行转换，这就需要自定义Converter实现时间转换
官方GitHub地址

自定义DateTimeJsonConverter

    public class DateTimeJsonConverter : JsonConverter<DateTime>
    {
        private readonly string _dateFormatString;
        public DateTimeJsonConverter()
        {
            _dateFormatString = "yyyy-MM-dd HH:mm:ss";
        }

        public DateTimeJsonConverter(string dateFormatString)
        {
            _dateFormatString = dateFormatString;
        }

        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.ToUniversalTime().ToString(_dateFormatString));
        }
    }

JsonTokenType枚举类型共有以下几种

  /// <summary>Defines the various JSON tokens that make up a JSON text.</summary>
  public enum JsonTokenType : byte
  {
    /// <summary>There is no value (as distinct from <see cref="F:System.Text.Json.JsonTokenType.Null" />).</summary>
    None,
    /// <summary>The token type is the start of a JSON object.</summary>
    StartObject,
    /// <summary>The token type is the end of a JSON object.</summary>
    EndObject,
    /// <summary>The token type is the start of a JSON array.</summary>
    StartArray,
    /// <summary>The token type is the end of a JSON array.</summary>
    EndArray,
    /// <summary>The token type is a JSON property name.</summary>
    PropertyName,
    /// <summary>The token type is a comment string.</summary>
    Comment,
    /// <summary>The token type is a JSON string.</summary>
    String,
    /// <summary>The token type is a JSON number.</summary>
    Number,
    /// <summary>The token type is the JSON literal true.</summary>
    True,
    /// <summary>The token type is the JSON literal false.</summary>
    False,
    /// <summary>The token type is the JSON literal null.</summary>
    Null,
  }

services.AddMvc 中 Newtonsoft.Json与System.Text.Json 配置区别

.netcore 2.1

            services
                //全局配置Json序列化处理
                .AddJsonOptions(options =>
                {
                    //忽略循环引用
                    options.SerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
                    //不使用驼峰样式的key
                    options.SerializerSettings.ContractResolver = new DefaultContractResolver();
                    //设置时间格式
                    options.SerializerSettings.DateFormatString = "yyyy-MM-dd HH:mm:ss";
                })

.netcore 3.1

            services.AddControllers()
                .AddJsonOptions(options =>
                {
                    //设置时间格式
                    options.JsonSerializerOptions.Converters.Add(new DateTimeJsonConverter("yyyy-MM-dd HH:mm:ss"));
                    //设置bool获取格式
                    options.JsonSerializerOptions.Converters.Add(new BoolJsonConverter());
                    //不使用驼峰样式的key
                    options.JsonSerializerOptions.PropertyNamingPolicy = null;
                    //不使用驼峰样式的key
                    options.JsonSerializerOptions.DictionaryKeyPolicy = null;
                    //获取或设置要在转义字符串时使用的编码器
                    options.JsonSerializerOptions.Encoder = javascriptEncoder.UnsafeRelaxedJsonEscaping;
                });

bool型转换问题

.netcore 3.1中接收的json中不能将 "true"/"false"识别为boolean的True/False，这也需要自定义Converter实现bool转换

namespace Kdniao.Core.Utility
{
    public class BoolJsonConverter : JsonConverter<bool>
    {
        public override bool Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
        {
            if (reader.TokenType == JsonTokenType.True || reader.TokenType == JsonTokenType.False)
                return reader.GetBoolean();

            return bool.Parse(reader.GetString());
        }

        public override void Write(Utf8JsonWriter writer, bool value, JsonSerializerOptions options)
        {
            writer.WriteBooleanValue(value);
        }
    }
}