C#中将xml文件反序列化为实例时采用基类还是派生类的知识点讨论

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace DeserializeTest
{
 public class SettingsBase
 {
 private string m_fileName;

 public string FileName 
 {
  get { return m_fileName; }
  set { m_fileName = value; }
 }
  
 }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace DeserializeTest
{
 public class WorldWindSettings : SettingsBase
 {
  public WorldWindSettings()
   : base()
  {
  }


  private string m_proxyUrl = "";

  public string ProxyUrl
  {
   get
   {
    return m_proxyUrl;
   }
   set
   {
    this.m_proxyUrl = value;
   }
  }
 }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.IO;
using System.Xml.Serialization;

namespace DeserializeTest
{
 class Program
 {
  static void Main(string[] args)
  {
   //测试1：测试将xml文件反序列化为基类实例。测试通过。只要xml文件的根节点的名字与被反序列化的类的名字一致即可
   string fileNameBase = @"D:\MyProject\DeserializeTest\DeserializeTest\bin\Debug\GobalConfig\SettingsBase.xml";
   SettingsBase settingsBase;
   XmlSerializer serBase = new XmlSerializer(typeof(SettingsBase));
   using (TextReader trBase = new StreamReader(fileNameBase))
   {
    settingsBase = (SettingsBase)serBase.Deserialize(trBase);
    settingsBase.FileName = fileNameBase;
   }

   //测试2：测试将xml文件反序列化为子类实例。测试通过。只要xml文件的根节点的名字与被反序列化的类的名字一致即可。当然了，用基类的实例引用去指向反序列化后的派生类的实例也是没问题的。
   string fileName = @"D:\MyProject\DeserializeTest\DeserializeTest\bin\Debug\GobalConfig\WorldWind.xml";
   SettingsBase settings;//当前了此处定义为WorldWindSettings settings;也没问题
   Type type = typeof(WorldWindSettings);//因为xml文件的根节点名称是WorldWindSettings，此处只能为WorldWindSettings，而不能为SettingsBase
   XmlSerializer ser = new XmlSerializer(type);
   using (TextReader tr = new StreamReader(fileName))
   {
    //settings = (WorldWindSettings)ser.Deserialize(tr);//这两句代码都可以通过！
    settings = (SettingsBase)ser.Deserialize(tr);
    settings.FileName = fileName;
   }

   System.Console.WriteLine("Hello");
  }
 }
}

<?xml version="1.0" encoding="utf-8"?>
<SettingsBase>
 <FileName>WorldWind.xml</FileName>
</SettingsBase>

<?xml version="1.0" encoding="utf-8"?>
<WorldWindSettings>
 <FileName>WorldWind.xml</FileName>
 <ProxyUrl>www.baidu.com</ProxyUrl>
</WorldWindSettings>