c# – 当我使用XmlSerialiser对其进行反序列化时,为什么我的DbNu

VB.NET：

If someObject Is DbNull.Value Then
    ...
End if

C#：

If (someObject == DbNull.Value)
{
    ...
}

但是最近,我使用XmlSerialiser序列化了一个DbNull实例,突然间它不再是单例了.类型比较操作(如C#(obj是DBNull))工作正常.

代码如下：

[Serializable,System.Xml.Serialization.XmlInclude(typeof(DBNull))]
public class SerialiseMe
{
    public SerialiseMe() { }

    public SerialiseMe(object value)
    {
        this.ICanBeDbNull = value;
    }
    public Object ICanBeDbNull { get; set; }
}

public void Foo()
{
    var serialiseDbNull = new SerialiseMe(DBNull.Value);
    var serialiser = new System.Xml.Serialization.XmlSerializer(typeof(SerialiseMe));
    var ms = new System.IO.MemoryStream();
    serialiser.Serialize(ms,serialiseDbNull);
    ms.Seek(0,System.IO.SeekOrigin.Begin);
    var deSerialisedDbNull = (SerialiseMe)serialiser.Deserialize(ms);

    // Is false,WTF!
    var equalsDbNullDeserialised = deSerialisedDbNull.ICanBeDbNull == DBNull.Value;
    // Is false,WTF!
    var refEqualsDbNullDeserialised = object.ReferenceEquals(deSerialisedDbNull.ICanBeDbNull,DBNull.Value);
    // Is true.
    var convertIsDbNullDeserialised = Convert.IsDBNull(deSerialisedDbNull.ICanBeDbNull);
    // Is true.
    var isIsDbNullDeserialised = deSerialisedDbNull.ICanBeDbNull is DBNull;

}

为什么会这样？它是如何发生的？它可能发生在任何其他静态字段中吗？

PS：我知道VB代码示例正在进行参考比较,而c#正在调用Object.Equals.两者都与DBNull具有相同的行为.我经常使用VB.