ExtensionDataObject ExtensionDataObject ExtensionDataObject ExtensionDataObject Class

定義

儲存已建立版本之資料合約的資料,此資料合約已因加入新成員而得到擴充。Stores data from a versioned data contract that has been extended by adding new members.

public ref class ExtensionDataObject sealed
public sealed class ExtensionDataObject
type ExtensionDataObject = class
Public NotInheritable Class ExtensionDataObject
繼承
ExtensionDataObjectExtensionDataObjectExtensionDataObjectExtensionDataObject

範例

下列程式碼範例會序列化型別 (PersonVersion2) 的執行個體,這個型別是可序列化型別 (Person) 的第二個版本。The following code serializes an instance of a type (PersonVersion2) that is the second version of the serializable type (Person). 第二個版本包含第一個版本沒有呈現的額外資料 (ID 欄位)。The second version contains extra data (ID field) that is not present in the first version. 接著,這段程式碼會將 XML 文件還原序列化為 Person 物件,然後立即重新序列化此包含額外資料的物件。The code then deserializes the XML document into a Person object, then immediately reserializes the object including the extra data. 最後,這段程式碼會將新的 XML 還原序列化為 PersonVersion2 物件,然後將完整資料寫入至主控台,以證明資料已完成從舊版型別開始與結束的來回流程。Finally, the code deserializes the new XML into a PersonVersion2 object and writes the complete data to the console, proving that the data has made a round trip to and from an older version of the type. 請注意,DataContractAttribute 屬性必須套用 Name,並且 Namespace 屬性已設定為與原始類別相同的名稱和命名空間。Note that the DataContractAttribute attribute must be applied with the Name and Namespace properties set to the same name and namespace as the original class.

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

// Implement the IExtensibleDataObject interface 
// to store the extra data for future versions.
[DataContract(
    Name = "Person",
    Namespace = "http://www.cohowinery.com/employees")]
class Person : IExtensibleDataObject
{
    // To implement the IExtensibleDataObject interface,
    // you must implement the ExtensionData property. The property
    // holds data from future versions of the class for backward
    // compatibility.
    private ExtensionDataObject extensionDataObject_value;
    public ExtensionDataObject ExtensionData
    {
        get
        {
            return extensionDataObject_value;
        }
        set
        {
            extensionDataObject_value = value;
        }
    }
    [DataMember]
    public string Name;
}

// The second version of the class adds a new field. The field's 
// data is stored in the ExtensionDataObject field of
// the first version (Person). You must also set the Name property 
// of the DataContractAttribute to match the first version. 
// If necessary, also set the Namespace property so that the 
// name of the contracts is the same.
[DataContract(Name = "Person",
    Namespace = "http://www.cohowinery.com/employees")]
class PersonVersion2 : IExtensibleDataObject
{
    // Best practice: add an Order number to new members.
    [DataMember(Order=2)]
    public int ID;

    [DataMember]
    public string Name;

    private ExtensionDataObject extensionDataObject_value;
    public ExtensionDataObject ExtensionData
    {
        get
        {
            return extensionDataObject_value;
        }
        set
        {
            extensionDataObject_value = value;
        }
    }
}
public sealed class Program
{
    private Program()
    {
        // Private constructor to prevent creation of this class.
    }

    public static void Main()
    {
        try
        {
            WriteVersion2("V2.xml");
            WriteToVersion1("v2.xml");
            ReadVersion2("v2.xml");
        }
        catch (SerializationException exc)
        {
            Console.WriteLine("{0}: {1}", exc.Message, exc.StackTrace);
        }
        finally
        {
            Console.ReadLine();
        }
    }

    // Create an instance of the version 2.0 class. It has  
    // extra data (ID field) that version 1.0 does 
    // not understand.
    static void WriteVersion2(string path)
    {
        Console.WriteLine("Creating a version 2 object");
        PersonVersion2 p2 = new PersonVersion2();
        p2.Name = "Elizabeth";
        p2.ID = 2006;

        Console.WriteLine("Object data includes an ID");
        Console.WriteLine("\t Name: {0}", p2.Name);
        Console.WriteLine("\t ID: {0} \n", p2.ID);
        // Create an instance of the DataContractSerializer.
        DataContractSerializer ser =
            new DataContractSerializer(typeof(PersonVersion2));

        Console.WriteLine("Serializing the v2 object to a file. \n\n");
        FileStream fs = new FileStream(path, FileMode.Create);
        ser.WriteObject(fs, p2);
        fs.Close();
    }

    // Deserialize version 2 data to a version 1 object.
    static void WriteToVersion1(string path)
    {
        // Create the serializer using the version 1 type.
        DataContractSerializer ser =
            new DataContractSerializer(typeof(Person));

        FileStream fs = new FileStream(path, FileMode.Open);
        XmlDictionaryReader reader =
           XmlDictionaryReader.CreateTextReader(fs, new XmlDictionaryReaderQuotas());
        Console.WriteLine
            ("Deserializing v2 data to v1 object. \n\n");

        Person p1 = (Person)ser.ReadObject(reader, false);

        Console.WriteLine("V1 data has only a Name field.");
        Console.WriteLine("But the v2 data is stored in the ");
        Console.WriteLine("ExtensionData property. \n\n");
        Console.WriteLine("\t Name: {0} \n", p1.Name);

        fs.Close();

        // Change data in the object.
        p1.Name = "John";
        Console.WriteLine("Changed the Name value to 'John' ");
        Console.Write("and reserializing the object to version 2 \n\n");
        // Reserialize the object.
        fs = new FileStream(path, FileMode.Create);
        ser.WriteObject(fs, p1);
        fs.Close();
    }

    // Deserialize a version 2.0 object. 
    public static void ReadVersion2(string path)
    {
        FileStream fs = new FileStream(path, FileMode.Open);
        DataContractSerializer ser = new DataContractSerializer(typeof(PersonVersion2));

        Console.WriteLine("Deserializing new data to version 2 \n\n");
        PersonVersion2 p2 = (PersonVersion2)ser.ReadObject(fs);
        fs.Close();

        Console.WriteLine("The data includes the old ID field value. \n");
        Console.WriteLine("\t (New) Name: {0}", p2.Name);
        Console.WriteLine("\t ID: {0} \n", p2.ID);
    }
}
' Implement the IExtensibleDataObject interface 
' to store the extra data for future versions.
<DataContract(Name := "Person", [Namespace] := "http://www.cohowinery.com/employees")>  _
Class Person
    Implements IExtensibleDataObject
    ' To implement the IExtensibleDataObject interface,
    ' you must implement the ExtensionData property. The property
    ' holds data from future versions of the class for backward
    ' compatibility.
    Private extensionDataObject_value As ExtensionDataObject
    
    Public Property ExtensionData() As ExtensionDataObject _
       Implements IExtensibleDataObject.ExtensionData
        Get
            Return extensionDataObject_value
        End Get
        Set
            extensionDataObject_value = value
        End Set
    End Property
    <DataMember()>  _
    Public Name As String
End Class 

' The second version of the class adds a new field. The field's 
' data is stored in the ExtensionDataObject field of
' the first version (Person). You must also set the Name property 
' of the DataContractAttribute to match the first version. 
' If necessary, also set the Namespace property so that the 
' name of the contracts is the same.

<DataContract(Name := "Person", [Namespace] := "http://www.cohowinery.com/employees")>  _
Class PersonVersion2
    Implements IExtensibleDataObject

    ' Best practice: add an Order number to new members.
    <DataMember(Order:=2)>  _
    Public ID As Integer
    
    <DataMember()>  _
    Public Name As String
    
    Private extensionDataObject_value As ExtensionDataObject
    
    Public Property ExtensionData() As ExtensionDataObject _
       Implements IExtensibleDataObject.ExtensionData
        Get
            Return extensionDataObject_value
        End Get
        Set
            extensionDataObject_value = value
        End Set
    End Property
End Class 

NotInheritable Public Class Program

    ' Private constructor to prevent creation of this class.
    Private Sub New() 
    
    End Sub 
    
    
    Public Shared Sub Main() 
        Try
            WriteVersion2("V2.xml")
            WriteToVersion1("v2.xml")
            ReadVersion2("v2.xml")
        Catch exc As SerializationException
            Console.WriteLine("{0}: {1}", exc.Message, exc.StackTrace)
        Finally
            Console.ReadLine()
        End Try
    
    End Sub 
    
    ' Create an instance of the version 2.0 class. It has  
    ' extra data (ID field) that version 1.0 does 
    ' not understand.
    Shared Sub WriteVersion2(ByVal path As String) 
        Console.WriteLine("Creating a version 2 object")
        Dim p2 As New PersonVersion2()
        p2.Name = "Elizabeth"
        p2.ID = 2006
        
        Console.WriteLine("Object data includes an ID")
        Console.WriteLine(vbTab + " Name: {0}", p2.Name)
        Console.WriteLine(vbTab + " ID: {0} " + vbLf, p2.ID)
        ' Create an instance of the DataContractSerializer.
        Dim ser As New DataContractSerializer(GetType(PersonVersion2))
        
        Console.WriteLine("Serializing the v2 object to a file. " + vbLf + vbLf)
        Dim fs As New FileStream(path, FileMode.Create)
        ser.WriteObject(fs, p2)
        fs.Close()
    End Sub 
    
    ' Deserialize version 2 data to a version 1 object.
    Shared Sub WriteToVersion1(ByVal path As String) 
        ' Create the serializer using the version 1 type.
        Dim ser As New DataContractSerializer(GetType(Person))
        
        Dim fs As New FileStream(path, FileMode.Open)
        Dim reader As XmlDictionaryReader = _
            XmlDictionaryReader.CreateTextReader(fs, New XmlDictionaryReaderQuotas())
        Console.WriteLine("Deserializing v2 data to v1 object. " + vbLf + vbLf)
        
        Dim p1 As Person = CType(ser.ReadObject(reader, False), Person)
        
        Console.WriteLine("V1 data has only a Name field.")
        Console.WriteLine("But the v2 data is stored in the ")
        Console.WriteLine("ExtensionData property. " + vbLf + vbLf)
        Console.WriteLine(vbTab + " Name: {0} " + vbLf, p1.Name)
        
        reader.Close()
        fs.Close()
        
        ' Change data in the object.
        p1.Name = "John"
        Console.WriteLine("Changed the Name value to 'John' ")
        Console.Write("and reserializing the object to version 2 " + vbLf + vbLf)
        ' Reserialize the object.
        fs = New FileStream(path, FileMode.Create)
        ser.WriteObject(fs, p1)
        fs.Close()
    
    End Sub 
    
    ' Deserialize a version 2.0 object. 
    Public Shared Sub ReadVersion2(ByVal path As String) 
        Dim fs As New FileStream(path, FileMode.Open)
        Dim ser As New DataContractSerializer(GetType(PersonVersion2))
        
        Console.WriteLine("Deserializing new data to version 2 " + vbLf + vbLf)
        Dim p2 As PersonVersion2 = CType(ser.ReadObject(fs), PersonVersion2)
        fs.Close()
        
        Console.WriteLine("The data includes the old ID field value. " + vbLf)
        Console.WriteLine(vbTab + " (New) Name: {0}", p2.Name)
        Console.WriteLine(vbTab + " ID: {0} " + vbLf, p2.ID)
    
    End Sub 
End Class 

備註

ExtensionDataObject 是一種結構,它會儲存 XmlObjectSerializer 在還原序列化 (Deserialization) 作業期間所遇到的額外資料。The ExtensionDataObject is the structure that stores extra data encountered by the XmlObjectSerializer during deserialization operations. 序列化 (Serialization) 會使用這個結構將額外資料寫入至已序列化的執行個體。The structure is used by serialization to write the extra data into the serialized instance. ExtensionData 執行個體的 IExtensibleDataObject 屬性會傳回這個結構。The structure is returned by the ExtensionData property of the IExtensibleDataObject interface.

方法

Equals(Object) Equals(Object) Equals(Object) Equals(Object)

判斷指定的物件是否等於目前的物件。Determines whether the specified object is equal to the current object.

(Inherited from Object)

GetHashCode() GetHashCode() GetHashCode() GetHashCode()

做為預設雜湊函式。Serves as the default hash function.

(Inherited from Object)

GetType() GetType() GetType() GetType()

取得目前執行個體的 TypeGets the Type of the current instance.

(Inherited from Object)

MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

建立目前 Object 的淺層複本 (Shallow Copy)。Creates a shallow copy of the current Object.

(Inherited from Object)

ToString() ToString() ToString() ToString()

傳回代表目前物件的字串。Returns a string that represents the current object.

(Inherited from Object)

適用於

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