XmlAttributeOverrides XmlAttributeOverrides XmlAttributeOverrides XmlAttributeOverrides Class

Definition

Ermöglicht das Überschreiben der Attribute von Eigenschaften, Feldern und Klassen beim Serialisieren oder Deserialisieren eines Objekts mit XmlSerializer.Allows you to override property, field, and class attributes when you use the XmlSerializer to serialize or deserialize an object.

public ref class XmlAttributeOverrides
public class XmlAttributeOverrides
type XmlAttributeOverrides = class
Public Class XmlAttributeOverrides
Vererbung
XmlAttributeOverridesXmlAttributeOverridesXmlAttributeOverridesXmlAttributeOverrides

Beispiele

Im folgenden Beispiel wird die Klasse serialisiert Orchestra, die ein einzelnes Feld namens enthält Instruments , die gibt ein Array von Instrument Objekte.The following example serializes a class named Orchestra, which contains a single field named Instruments that returns an array of Instrument objects. Eine zweite Klasse namens Brass erbt von der Instrument Klasse.A second class named Brass inherits from the Instrument class. Im Beispiel wird eine Instanz von der XmlAttributeOverrides Klasse überschreiben die Instrument Feld, sodass das Feld akzeptiert Brass Objekte.The example uses an instance of the XmlAttributeOverrides class to override the Instrument field, allowing the field to accept Brass objects.

#using <System.Xml.dll>
#using <System.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml::Serialization;

public ref class Instrument
{
public:
   String^ Name;
};

public ref class Brass: public Instrument
{
public:
   bool IsValved;
};

public ref class Orchestra
{
public:
   array<Instrument^>^Instruments;
};

void SerializeObject( String^ filename )
{
   /* Each overridden field, property, or type requires 
      an XmlAttributes object. */
   XmlAttributes^ attrs = gcnew XmlAttributes;

   /* Create an XmlElementAttribute to override the 
      field that returns Instrument objects. The overridden field
      returns Brass objects instead. */
   XmlElementAttribute^ attr = gcnew XmlElementAttribute;
   attr->ElementName = "Brass";
   attr->Type = Brass::typeid;

   // Add the element to the collection of elements.
   attrs->XmlElements->Add( attr );

   // Create the XmlAttributeOverrides object.
   XmlAttributeOverrides^ attrOverrides = gcnew XmlAttributeOverrides;

   /* Add the type of the class that contains the overridden 
      member and the XmlAttributes to override it with to the 
      XmlAttributeOverrides object. */
   attrOverrides->Add( Orchestra::typeid, "Instruments", attrs );

   // Create the XmlSerializer using the XmlAttributeOverrides.
   XmlSerializer^ s = gcnew XmlSerializer( Orchestra::typeid,attrOverrides );

   // Writing the file requires a TextWriter.
   TextWriter^ writer = gcnew StreamWriter( filename );

   // Create the object that will be serialized.
   Orchestra^ band = gcnew Orchestra;

   // Create an object of the derived type.
   Brass^ i = gcnew Brass;
   i->Name = "Trumpet";
   i->IsValved = true;
   array<Instrument^>^myInstruments = {i};
   band->Instruments = myInstruments;

   // Serialize the object.
   s->Serialize( writer, band );
   writer->Close();
}

void DeserializeObject( String^ filename )
{
   XmlAttributeOverrides^ attrOverrides = gcnew XmlAttributeOverrides;
   XmlAttributes^ attrs = gcnew XmlAttributes;

   // Create an XmlElementAttribute to override the Instrument.
   XmlElementAttribute^ attr = gcnew XmlElementAttribute;
   attr->ElementName = "Brass";
   attr->Type = Brass::typeid;

   // Add the XmlElementAttribute to the collection of objects.
   attrs->XmlElements->Add( attr );
   attrOverrides->Add( Orchestra::typeid, "Instruments", attrs );

   // Create the XmlSerializer using the XmlAttributeOverrides.
   XmlSerializer^ s = gcnew XmlSerializer( Orchestra::typeid,attrOverrides );
   FileStream^ fs = gcnew FileStream( filename,FileMode::Open );
   Orchestra^ band = dynamic_cast<Orchestra^>(s->Deserialize( fs ));
   Console::WriteLine( "Brass:" );

   /* The difference between deserializing the overridden 
      XML document and serializing it is this: To read the derived 
      object values, you must declare an object of the derived type 
      (Brass), and cast the Instrument instance to it. */
   Brass^ b;
   System::Collections::IEnumerator^ myEnum = band->Instruments->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      Instrument^ i = safe_cast<Instrument^>(myEnum->Current);
      b = dynamic_cast<Brass^>(i);
      Console::WriteLine( "{0}\n{1}", b->Name, b->IsValved );
   }
}

int main()
{
   SerializeObject( "Override.xml" );
   DeserializeObject( "Override.xml" );
}
using System;
using System.IO;
using System.Xml.Serialization;

public class Orchestra
{
   public Instrument[] Instruments;
}   

public class Instrument
{
   public string Name;
}

public class Brass:Instrument
{
   public bool IsValved;
}

public class Run
{
    public static void Main()
    {
       Run test = new Run();
       test.SerializeObject("Override.xml");
       test.DeserializeObject("Override.xml");
    }

    public void SerializeObject(string filename)
    {
      /* Each overridden field, property, or type requires 
      an XmlAttributes object. */
      XmlAttributes attrs = new XmlAttributes();

      /* Create an XmlElementAttribute to override the 
      field that returns Instrument objects. The overridden field
      returns Brass objects instead. */
      XmlElementAttribute attr = new XmlElementAttribute();
      attr.ElementName = "Brass";
      attr.Type = typeof(Brass);

      // Add the element to the collection of elements.
      attrs.XmlElements.Add(attr);

      // Create the XmlAttributeOverrides object.
      XmlAttributeOverrides attrOverrides = new XmlAttributeOverrides();

      /* Add the type of the class that contains the overridden 
      member and the XmlAttributes to override it with to the 
      XmlAttributeOverrides object. */
      attrOverrides.Add(typeof(Orchestra), "Instruments", attrs);

      // Create the XmlSerializer using the XmlAttributeOverrides.
      XmlSerializer s = 
      new XmlSerializer(typeof(Orchestra), attrOverrides);

      // Writing the file requires a TextWriter.
      TextWriter writer = new StreamWriter(filename);

      // Create the object that will be serialized.
      Orchestra band = new Orchestra();
      
      // Create an object of the derived type.
      Brass i = new Brass();
      i.Name = "Trumpet";
      i.IsValved = true;
      Instrument[] myInstruments = {i};
      band.Instruments = myInstruments;

      // Serialize the object.
      s.Serialize(writer,band);
      writer.Close();
   }

   public void DeserializeObject(string filename)
   {
      XmlAttributeOverrides attrOverrides = 
         new XmlAttributeOverrides();
      XmlAttributes attrs = new XmlAttributes();

      // Create an XmlElementAttribute to override the Instrument.
      XmlElementAttribute attr = new XmlElementAttribute();
      attr.ElementName = "Brass";
      attr.Type = typeof(Brass);

      // Add the XmlElementAttribute to the collection of objects.
      attrs.XmlElements.Add(attr);

      attrOverrides.Add(typeof(Orchestra), "Instruments", attrs);

      // Create the XmlSerializer using the XmlAttributeOverrides.
      XmlSerializer s = 
      new XmlSerializer(typeof(Orchestra), attrOverrides);

      FileStream fs = new FileStream(filename, FileMode.Open);
      Orchestra band = (Orchestra) s.Deserialize(fs);
      Console.WriteLine("Brass:");

      /* The difference between deserializing the overridden 
      XML document and serializing it is this: To read the derived 
      object values, you must declare an object of the derived type 
      (Brass), and cast the Instrument instance to it. */
      Brass b;
      foreach(Instrument i in band.Instruments) 
      {
         b = (Brass)i;
         Console.WriteLine(
         b.Name + "\n" + 
         b.IsValved);
      }
   }
}

Option Explicit
Option Strict

Imports System
Imports System.IO
Imports System.Xml.Serialization
Imports Microsoft.VisualBasic


Public Class Orchestra
    Public Instruments() As Instrument
End Class

Public Class Instrument
    Public Name As String
End Class

Public Class Brass
    Inherits Instrument
    Public IsValved As Boolean
End Class

Public Class Run
    
    Public Shared Sub Main()
        Dim test As New Run()
        test.SerializeObject("Override.xml")
        test.DeserializeObject("Override.xml")
    End Sub
        
    Public Sub SerializeObject(ByVal filename As String)
        ' Each overridden field, property, or type requires
        ' an XmlAttributes object. 
        Dim attrs As New XmlAttributes()
        
        ' Create an XmlElementAttribute to override the
        ' field that returns Instrument objects. The overridden field
        ' returns Brass objects instead. 
        Dim attr As New XmlElementAttribute()
        attr.ElementName = "Brass"
        attr.Type = GetType(Brass)
        
        ' Add the element to the collection of elements.
        attrs.XmlElements.Add(attr)
        
        ' Create the XmlAttributeOverrides object.
        Dim attrOverrides As New XmlAttributeOverrides()
        
        ' Add the type of the class that contains the overridden
        ' member and the XmlAttributes to override it with to the
        ' XmlAttributeOverrides object. 
        attrOverrides.Add(GetType(Orchestra), "Instruments", attrs)
        
        ' Create the XmlSerializer using the XmlAttributeOverrides.
        Dim s As New XmlSerializer(GetType(Orchestra), attrOverrides)
        
        ' Writing the file requires a TextWriter.
        Dim writer As New StreamWriter(filename)
        
        ' Create the object that will be serialized.
        Dim band As New Orchestra()
        
        ' Create an object of the derived type.
        Dim i As New Brass()
        i.Name = "Trumpet"
        i.IsValved = True
        Dim myInstruments() As Instrument = {i}
        band.Instruments = myInstruments
        
        ' Serialize the object.
        s.Serialize(writer, band)
        writer.Close()
    End Sub    
    
    Public Sub DeserializeObject(filename As String)
        Dim attrOverrides As New XmlAttributeOverrides()
        Dim attrs As New XmlAttributes()
        
        ' Create an XmlElementAttribute to override the Instrument.
        Dim attr As New XmlElementAttribute()
        attr.ElementName = "Brass"
        attr.Type = GetType(Brass)
        
        ' Add the XmlElementAttribute to the collection of objects.
        attrs.XmlElements.Add(attr)
        
        attrOverrides.Add(GetType(Orchestra), "Instruments", attrs)
        
        ' Create the XmlSerializer using the XmlAttributeOverrides.
        Dim s As New XmlSerializer(GetType(Orchestra), attrOverrides)
        
        Dim fs As New FileStream(filename, FileMode.Open)
        Dim band As Orchestra = CType(s.Deserialize(fs), Orchestra)
        Console.WriteLine("Brass:")
        
        ' The difference between deserializing the overridden
        ' XML document and serializing it is this: To read the derived
        ' object values, you must declare an object of the derived type
        ' (Brass), and cast the Instrument instance to it. 
        Dim b As Brass
        Dim i As Instrument
        For Each i In  band.Instruments
            b = CType(i, Brass)
            Console.WriteLine(b.Name & ControlChars.Cr & b.IsValved)
        Next i
    End Sub
End Class

Hinweise

Die XmlAttributeOverrides ermöglicht die XmlSerializer überschreiben die Standardmethode für einen Satz von Objekten zu serialisieren.The XmlAttributeOverrides enables the XmlSerializer to override the default way of serializing a set of objects. Überschreiben Serialisierung auf diese Weise besitzt zwei Verwendungen: zuerst können Sie steuern, und erweitern Sie die Serialisierung von Objekten in eine DLL-Datei – selbst wenn Sie keinen Zugriff auf die Quelle haben Andererseits können Sie einen Satz von serialisierbare Klassen erstellen, aber der Objekte auf verschiedene Weise zu serialisieren.Overriding serialization in this way has two uses: first, you can control and augment the serialization of objects found in a DLL--even if you do not have access to the source; second, you can create one set of serializable classes, but serialize the objects in multiple ways. Beispielsweise können statt des Serialisierens von Membern der Instanz einer Klasse als XML-Elemente, Sie sie als XML-Attribute, serialisieren resultierende in einem Dokument eine effizientere an den Transport.For example, instead of serializing members of a class instance as XML elements, you can serialize them as XML attributes, resulting in a more efficient document to transport.

Nach der Erstellung einer XmlAttributeOverrides Objekt, übergeben Sie es als Argument an die XmlSerializer Konstruktor.After you create an XmlAttributeOverrides object, you pass it as an argument to the XmlSerializer constructor. Die resultierende XmlSerializer verwendet die Daten von der XmlAttributeOverrides zum Überschreiben der Attribute, die steuern, wie die Objekte serialisiert werden.The resulting XmlSerializer uses the data contained by the XmlAttributeOverrides to override attributes that control how objects are serialized. Zu diesem Zweck die XmlAttributeOverrides enthält eine Auflistung von Objekttypen, die außer Kraft gesetzt werden, sowie einen XmlAttributes jeden außer Kraft gesetzte Objekttyp zugeordnete Objekt.To accomplish this, the XmlAttributeOverrides contains a collection of the object types that are overridden, as well as an XmlAttributes object associated with each overridden object type. Die XmlAttributes -Objekt selbst enthält einen entsprechenden Satz von Attributobjekte, die steuern, wie jedes Feld, Eigenschaft oder Klasse serialisiert wird.The XmlAttributes object itself contains an appropriate set of attribute objects that control how each field, property, or class is serialized.

Der Prozess zum Erstellen und Verwenden einer XmlAttributeOverrides Objekt lautet wie folgt:The process for creating and using an XmlAttributeOverrides object is as follows:

  1. Erstellen Sie eine XmlAttributes Objekt.Create an XmlAttributes object.

  2. Erstellen Sie ein Attributobjekt, das für das Objekt, das überschrieben wird geeignet ist.Create an attribute object that is appropriate to the object being overridden. Um ein Feld oder eine Eigenschaft zu überschreiben, z. B. Erstellen einer XmlElementAttribute, mit dem neuen abgeleiteten Typ.For example, to override a field or property, create an XmlElementAttribute, using the new, derived type. Sie können wahlweise eine neue zuweisen ElementName, oder Namespace , Attributnamen oder den Namespace der Basisklasse überschreibt.You can optionally assign a new ElementName, or Namespace that overrides the base class's attribute name or namespace.

  3. Fügen Sie das Attribute-Objekt an die entsprechende XmlAttributes Eigenschaft oder Auflistung.Add the attribute object to the appropriate XmlAttributes property or collection. Würden Sie z. B. Hinzufügen der XmlElementAttribute auf die XmlElements Auflistung von der XmlAttributes -Objekt, wobei den Namen des Members, die überschrieben wird.For example, you would add the XmlElementAttribute to the XmlElements collection of the XmlAttributes object, specifying the member name that is being overridden.

  4. Erstellen Sie eine XmlAttributeOverrides Objekt.Create an XmlAttributeOverrides object.

  5. Mithilfe der Add -Methode hinzufügen der XmlAttributes -Objekt an die XmlAttributeOverrides Objekt.Using the Add method, add the XmlAttributes object to the XmlAttributeOverrides object. Wenn das Objekt überschrieben wird ein XmlRootAttribute oder XmlTypeAttribute, müssen Sie nur den Typ des Objekts außer Kraft gesetzte angeben.If the object being overridden is an XmlRootAttribute or XmlTypeAttribute, you need only to specify the type of the overridden object. Aber wenn Sie ein Feld oder Eigenschaft außer Kraft gesetzt werden, müssen Sie auch den Namen des überschriebenen Member angeben.But if you are overriding a field or property, you must also specify the name of the overridden member.

  6. Beim Erstellen der XmlSerializer, übergeben die XmlAttributeOverrides auf die XmlSerializer Konstruktor.When constructing the XmlSerializer, pass the XmlAttributeOverrides to the XmlSerializer constructor.

  7. Verwenden Sie die resultierende XmlSerializer zum Serialisieren oder Deserialisieren Objekte der abgeleiteten Klasse.Use the resulting XmlSerializer to serialize or deserialize the derived class objects.

Konstruktoren

XmlAttributeOverrides() XmlAttributeOverrides() XmlAttributeOverrides() XmlAttributeOverrides()

Initialisiert eine neue Instanz der XmlAttributeOverrides-Klasse.Initializes a new instance of the XmlAttributeOverrides class.

Eigenschaften

Item[Type, String] Item[Type, String] Item[Type, String] Item[Type, String]

Ruft das dem angegebenen (Basisklassen-)Typ zugeordnete Objekt ab.Gets the object associated with the specified (base-class) type. Durch den member-Parameter wird der zu überschreibende Member der Basisklasse angegeben.The member parameter specifies the base-class member that is overridden.

Item[Type] Item[Type] Item[Type] Item[Type]

Ruft das dem angegebenen Basisklassentyp zugeordnete Objekt ab.Gets the object associated with the specified, base-class, type.

Methoden

Add(Type, String, XmlAttributes) Add(Type, String, XmlAttributes) Add(Type, String, XmlAttributes) Add(Type, String, XmlAttributes)

Fügt der Auflistung von XmlAttributes-Objekten ein XmlAttributes-Objekt hinzu.Adds an XmlAttributes object to the collection of XmlAttributes objects. Der type-Parameter gibt ein Objekt an, das überschrieben werden soll.The type parameter specifies an object to be overridden. Der member-Parameter gibt den Namen des zu überschreibenden Members an.The member parameter specifies the name of a member that is overridden.

Add(Type, XmlAttributes) Add(Type, XmlAttributes) Add(Type, XmlAttributes) Add(Type, XmlAttributes)

Fügt der Auflistung von XmlAttributes-Objekten ein XmlAttributes-Objekt hinzu.Adds an XmlAttributes object to the collection of XmlAttributes objects. Der type-Parameter gibt ein Objekt an, das vom XmlAttributes-Objekt überschrieben werden soll.The type parameter specifies an object to be overridden by the XmlAttributes object.

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

Bestimmt, ob das angegebene Objekt mit dem aktuellen Objekt identisch ist.Determines whether the specified object is equal to the current object.

(Inherited from Object)
GetHashCode() GetHashCode() GetHashCode() GetHashCode()

Fungiert als Standardhashfunktion.Serves as the default hash function.

(Inherited from Object)
GetType() GetType() GetType() GetType()

Ruft den Type der aktuellen Instanz ab.Gets the Type of the current instance.

(Inherited from Object)
MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

Erstellt eine flache Kopie des aktuellen Object.Creates a shallow copy of the current Object.

(Inherited from Object)
ToString() ToString() ToString() ToString()

Gibt eine Zeichenfolge zurück, die das aktuelle Objekt darstellt.Returns a string that represents the current object.

(Inherited from Object)

Gilt für:

Siehe auch