Json.NET序列化后包含类型，保证序列化和反序列化的对象类型相同（转载）

This sample uses the TypeNameHandlingsetting to include type information when serializing JSON and read type information so that the create types are created when deserializing JSON.

Sample

---

Types

public abstract class Business
{
    public string Name { get; set; }
}

public class Hotel : Business
{
    public int Stars { get; set; }
}

public class Stockholder
{
    public string FullName { get; set; }
    public IList<Business> Businesses { get; set; }
}

Usage

Stockholder stockholder = new Stockholder
{
    FullName = "Steve Stockholder",
    Businesses = new List<Business>
    {
        new Hotel
        {
            Name = "Hudson Hotel",
            Stars =
        }
    }
};

string jsonTypeNameAll = JsonConvert.SerializeObject(stockholder, Formatting.Indented, new JsonSerializerSettings
{
    TypeNameHandling = TypeNameHandling.All
});

Console.WriteLine(jsonTypeNameAll);
// {
//   "$type": "Newtonsoft.Json.Samples.Stockholder, Newtonsoft.Json.Tests",
//   "FullName": "Steve Stockholder",
//   "Businesses": {
//     "$type": "System.Collections.Generic.List`1[[Newtonsoft.Json.Samples.Business, Newtonsoft.Json.Tests]], mscorlib",
//     "$values": [
//       {
//         "$type": "Newtonsoft.Json.Samples.Hotel, Newtonsoft.Json.Tests",
//         "Stars": 4,
//         "Name": "Hudson Hotel"
//       }
//     ]
//   }
// }

string jsonTypeNameAuto = JsonConvert.SerializeObject(stockholder, Formatting.Indented, new JsonSerializerSettings
{
    TypeNameHandling = TypeNameHandling.Auto
});

Console.WriteLine(jsonTypeNameAuto);
// {
//   "FullName": "Steve Stockholder",
//   "Businesses": [
//     {
//       "$type": "Newtonsoft.Json.Samples.Hotel, Newtonsoft.Json.Tests",
//       "Stars": 4,
//       "Name": "Hudson Hotel"
//     }
//   ]
// }

// for security TypeNameHandling is required when deserializing
Stockholder newStockholder = JsonConvert.DeserializeObject<Stockholder>(jsonTypeNameAuto, new JsonSerializerSettings
{
    TypeNameHandling = TypeNameHandling.Auto
});

Console.WriteLine(newStockholder.Businesses[].GetType().Name);
// Hotel

演示

---

现在我们来做个演示，新建一个.NET Core控制台项目，然后我们定义两个类Car和Person如下：

using Newtonsoft.Json;
using System;

namespace JsonNetTesting
{
    public class Car
    {
        public string Name { get; set; }
        public string Color { get; set; }
    }

    public class Person
    {
        public string Name { get; set; }
        public int Age { get; set; }
        public Car carField;
        public Car CarProperty
        {
            get;
            set;
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            Person person = new Person()
            {
                Name = "Jack",
                Age = ,
                carField = new Car()
                {
                    Name = "Benz",
                    Color = "Black"
                },
                CarProperty = new Car()
                {
                    Name = "BMW",
                    Color = "White"
                }
            };

            string json = JsonConvert.SerializeObject(person, new JsonSerializerSettings()
            {
                TypeNameHandling = TypeNameHandling.All,
                Formatting = Formatting.Indented
            });

            Console.WriteLine(json);

            person = JsonConvert.DeserializeObject<Person>(json, new JsonSerializerSettings()
            {
                TypeNameHandling = TypeNameHandling.All
            });

            Console.WriteLine("Press key to end...");
            Console.ReadKey();
        }
    }
}

可以看到当我们设置TypeNameHandling = TypeNameHandling.All后，本例中类Car和Person序列化为JSON后如下：

{
  "$type": "JsonNetTesting.Person, JsonNetTesting",
  "carField": {
    "$type": "JsonNetTesting.Car, JsonNetTesting",
    "Name": "Benz",
    "Color": "Black"
  },
  "Name": "Jack",
  "Age": 35,
  "CarProperty": {
    "$type": "JsonNetTesting.Car, JsonNetTesting",
    "Name": "BMW",
    "Color": "White"
  }
}

可以看到类Car和Person被序列化为JSON后，都自动生成了一个"$type"属性，用来标识它们是从什么.NET类型序列化而来的。

原文链接