派生对象列表的序列化

Question

我想将派生对象列表序列化为 json 并反序列化。序列化工作正常，反序列化无法将对象转换为派生类对象，所有对象都被反序列化为基类对象并丢失属于派生类的成员。 我有基类 AutoEvent，派生类 MouseClickEvent 和 ClickImageEvent，所以一次 我反序列化以列出所有对象都是 AutoEvent 类型。如何反序列化，以便将每个对象转换为派生类对象？

using System;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Reflection;
using System.Web.Script.Serialization;

namespace AutoEvent
{            
    public class AutoEvent
    {
        public string Name { get; set; }
        public int DelayMs { get; set; }
        public AutoEvent(string name, int delayMs)
        {
            Name = name;
            DelayMs = delayMs;
        }
        public AutoEvent() { }
    }

    public class MouseClickEvent : AutoEvent
    {
        public Rectangle RectArea { get; set; }
        public bool IsDoubleClick { get; set; }
        public MouseClickEvent(string name, int delayMs, Rectangle rectArea, bool isDoubleClick) : base(name, delayMs)
        {
            RectArea = rectArea;
            IsDoubleClick = isDoubleClick;
        }
        public MouseClickEvent() { }

    }

    public class ClickImageEvent : AutoEvent
    {
        public List<string> ImgFiles { get; set; }
        public Rectangle SearchArea { get; set; }
        public double ImgTolerance { get; set; }
        public double ImgError { get; set; }
        public bool IsDoubleClick { get; set; }
        public ClickImageEvent(string name, int delayMs, Rectangle searchArea, bool isDoubleClick, double imgTol, double imgErr) : base(name, delayMs)
        {
            SearchArea = searchArea;
            IsDoubleClick = isDoubleClick;
            ImgTolerance = imgTol;
            ImgError = imgErr;
        }
        public ClickImageEvent() { }

    }

    class Program
    {
        static void Main(string[] args)
        {
            string path = @"c:/nenad/testSer.txt";
            List<AutoEvent> events = new List<AutoEvent>();
            MouseClickEvent clickEvent1 = new MouseClickEvent("mouse click1", 100, new Rectangle(20, 30, 15, 10), true);
            MouseClickEvent clickEvent2 = new MouseClickEvent("mouse click2", 15, new Rectangle(20, 45, 15, 10), true);
            ClickImageEvent imgclick1 = new ClickImageEvent("image click1", 15, new Rectangle(20, 45, 555, 150), false, 0.1, 0.05);
            ClickImageEvent imgclick2 = new ClickImageEvent("image click2", 125, new Rectangle(2220, 45, 5525, 150), false, 0.15, 0.25);
            events.Add(clickEvent1);
            events.Add(clickEvent2);
            events.Add(imgclick1);
            events.Add(imgclick2);

            JavaScriptSerializer ser = new JavaScriptSerializer();
            string json = ser.Serialize(events);
            if (!File.Exists(path))
            {
                using (var h = File.Create(path)) ;
            }

            File.WriteAllText(path, json);

            json = File.ReadAllText(path);
            events = ser.Deserialize<List<AutoEvent>>(json);
            MouseClickEvent event1 = (MouseClickEvent)events[0]; // fails at runtime to convert 
            ClickImageEvent event2 = (ClickImageEvent)events[2]; // fails at runtime to convert 
        }
    }
}

Answer 1

来自关于javascriptserializer的文档

对于 .NET Framework 4.7.2 及更高版本，使用 System.Text.Json 命名空间中的 API 进行序列化和反序列化。对于早期版本的 .NET Framework，请使用 Newtonsoft.Json。此类型旨在为支持 AJAX 的应用程序提供序列化和反序列化功能

即您可能应该使用另一个 json 库。

如果您更喜欢 Json.Net，请参阅 Json.net serialize/deserialize derived types?。如果您更喜欢 System.Text.Json，请参阅How to serialize properties of derived classes with System.Text.Json

Answer 2

当你跑步时

  events = ser.Deserialize<List<AutoEvent>>(json);

你只能得到这个

[
  {
    "Name": "mouse click1",
    "DelayMs": 100
  },
  {
    "Name": "mouse click2",
    "DelayMs": 15
  },
  {
    "Name": "image click1",
    "DelayMs": 15
  },
  {
    "Name": "image click2",
    "DelayMs": 125
  }
]

json 中的内容无关紧要，因为您使用它进行反序列化，它将自动剪切为 AutoEvent 类中的数据。

为了获取所有信息，你必须使用最高的继承级别来反序列化，而不是最低的。这段代码在VS中测试过，运行正常。

List<ClickImageEvent> events1 = ser.Deserialize<List<ClickImageEvent>>(json);
 MouseClickEvent event1 = (MouseClickEvent)events[0]; 
 ClickImageEvent event2 = (ClickImageEvent)events[2];

所有类都应该相互继承

public class ClickImageEvent : MouseClickEvent
{
    public List<string> ImgFiles { get; set; }
    public Rectangle SearchArea { get; set; }
    public double ImgTolerance { get; set; }
    public double ImgError { get; set; }
    public ClickImageEvent(string name, int delayMs, Rectangle searchArea, bool isDoubleClick, double imgTol=0, double imgErr=0) : base(name, delayMs,searchArea, isDoubleClick)
    {
        SearchArea = searchArea;
        IsDoubleClick = isDoubleClick;
        ImgTolerance = imgTol;
        ImgError = imgErr;
    }
    public ClickImageEvent() { }

}

或者如果您只想从 AutoEvent 派生，您可以使用映射器或手动转换或使用 linq Select

 var ev =events[0]; 

MouseClickEvent event1 = new MouseClickEvent( ev.Name, ev.DelayMs, ev.SeachArea,...);

例如，如果您需要使用 linq 进行转换，则必须添加类的类型

public class AutoEvent
 {
  public string TypeName { get; set; } = "Auto";
.....
}

应该在创建对象时分配，在序列化之前。