我有一个简单的类层次结构,我想使用 System.Text.Json 对其进行序列化。
有3个班。基地是Shape
。继承的是Box
和Circle
。
我计划在我的前端应用程序上使用这些类作为标记联合,所以我只是引入了一个鉴别器属性Tag
。
我写了一个类型转换器,它支持这个层次结构的序列化/反序列化。
我想了解的是——这是否是实现此类功能的最佳方法。事实上,序列化的输出结果非常难看(我在下面的示例中添加了注释)。无论如何,我不确定它是否以最好的方式完成。
这是我如何实现序列化/反序列化的示例:
using System;
using System.Linq;
using System.Text.Json;
using System.Text.Json.Serialization;
namespace Serialization.Theory
{
public abstract class Shape
{
public abstract String Tag { get; }
}
public class Box : Shape
{
public override String Tag { get; } = nameof(Box);
public Single Width { get; set; }
public Single Height { get; set; }
public override String ToString()
{
return $"{Tag}: Width={Width}, Height={Height}";
}
}
public class Circle : Shape
{
public override String Tag { get; } = nameof(Circle);
public Single Radius { get; set; }
public override String ToString()
{
return $"{Tag}: Radius={Radius}";
}
}
public class ShapeConverter : JsonConverter<Shape>
{
public override Boolean CanConvert(Type typeToConvert)
{
return typeToConvert == typeof(Circle) || typeToConvert == typeof(Shape);
}
public override Shape Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
{
var raw = reader.GetString();
var doc = JsonDocument.Parse(raw);
var prop = doc.RootElement.EnumerateObject().Where(x => x.Name == "Tag").First();
var value = prop.Value.GetString();
switch (value)
{
case nameof(Circle):
return JsonSerializer.Deserialize<Circle>(raw);
case nameof(Box):
return JsonSerializer.Deserialize<Box>(raw);
default:
throw new NotSupportedException();
}
}
public override void Write(Utf8JsonWriter writer, Shape value, JsonSerializerOptions options)
{
if (value is Circle circle)
{
writer.WriteStringValue(JsonSerializer.SerializeToUtf8Bytes(circle));
}
else if (value is Box box)
{
writer.WriteStringValue(JsonSerializer.SerializeToUtf8Bytes(box));
}
}
}
class Program
{
static void Main(string[] args)
{
// Keep in base class references like it's a property on another object.
Shape origin1 = new Box { Width = 10, Height = 20 };
Shape origin2 = new Circle { Radius = 30 };
var settings = new JsonSerializerOptions();
settings.Converters.Add(new ShapeConverter());
var raw1 = JsonSerializer.Serialize(origin1, settings);
var raw2 = JsonSerializer.Serialize(origin2, settings);
Console.WriteLine(raw1); // "{\u0022Tag\u0022:\u0022Box\u0022,\u0022Width\u0022:10,\u0022Height\u0022:20}"
Console.WriteLine(raw2); // "{\u0022Tag\u0022:\u0022Circle\u0022,\u0022Radius\u0022:30}"
var restored1 = JsonSerializer.Deserialize<Shape>(raw1, settings);
var restored2 = JsonSerializer.Deserialize<Shape>(raw2, settings);
Console.WriteLine(restored1); // Box: Width=10, Height=20
Console.WriteLine(restored2); // Circle: Radius=30
}
}
}