ExtensionDataObject Classe
Definizione
Importante
Alcune informazioni sono relative alla release non definitiva del prodotto, che potrebbe subire modifiche significative prima della release definitiva. Microsoft non riconosce alcuna garanzia, espressa o implicita, in merito alle informazioni qui fornite.
Archivia i dati da un contratto dati con controllo delle versioni esteso aggiungendo nuovi membri.
public ref class ExtensionDataObject sealedpublic sealed class ExtensionDataObjecttype ExtensionDataObject = classPublic NotInheritable Class ExtensionDataObject- Ereditarietà
-
ExtensionDataObject
Esempio
Il codice seguente serializza un'istanza di un tipo (PersonVersion2) che rappresenta la seconda versione del tipo serializzabile (Person). La seconda versione contiene dati aggiuntivi (ID campo) non presenti nella prima versione. Il codice deserializza quindi il documento XML in un Person oggetto e quindi reinirializza immediatamente l'oggetto, inclusi i dati aggiuntivi. Infine, il codice deserializza il nuovo codice XML in un PersonVersion2 oggetto e scrive i dati completi nella console, dimostrando che i dati hanno effettuato un round trip verso e da una versione precedente del tipo. Si noti che l'attributo DataContractAttribute deve essere applicato con le Name proprietà e Namespace impostate sullo stesso nome e spazio dei nomi della classe originale.
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
Commenti
ExtensionDataObject è la struttura che archivia dati aggiuntivi rilevati da XmlObjectSerializer durante le operazioni di deserializzazione. La struttura viene utilizzata dalla serializzazione per scrivere i dati aggiuntivi nell'istanza serializzata. La struttura viene restituita dalla ExtensionData proprietà dell'interfaccia IExtensibleDataObject .
Metodi
| Nome | Descrizione |
|---|---|
| Equals(Object) |
Determina se l'oggetto specificato è uguale all'oggetto corrente. (Ereditato da Object) |
| GetHashCode() |
Funge da funzione hash predefinita. (Ereditato da Object) |
| GetType() |
Ottiene il Type dell'istanza corrente. (Ereditato da Object) |
| MemberwiseClone() |
Crea una copia superficiale del Objectcorrente. (Ereditato da Object) |
| ToString() |
Restituisce una stringa che rappresenta l'oggetto corrente. (Ereditato da Object) |
