XmlAttributeOverrides XmlAttributeOverrides XmlAttributeOverrides XmlAttributeOverrides Class

Definición

Permite reemplazar los atributos de las propiedades, campos y clases al utilizar XmlSerializer para serializar o deserializar un objeto.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
Herencia
XmlAttributeOverridesXmlAttributeOverridesXmlAttributeOverridesXmlAttributeOverrides

Ejemplos

El siguiente ejemplo serializa una clase denominada Orchestra, que contiene un solo campo denominado Instruments que devuelve una matriz de Instrument objetos.The following example serializes a class named Orchestra, which contains a single field named Instruments that returns an array of Instrument objects. Una segunda clase denominada Brass hereda el Instrument clase.A second class named Brass inherits from the Instrument class. En el ejemplo se utiliza una instancia de la XmlAttributeOverrides clase para invalidar el Instrument campo, lo que permite el campo puede aceptar Brass objetos.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

Comentarios

El XmlAttributeOverrides permite la XmlSerializer para reemplazar el modo predeterminado de serialización de un conjunto de objetos.The XmlAttributeOverrides enables the XmlSerializer to override the default way of serializing a set of objects. Invalidar la serialización de este modo tiene dos usos: en primer lugar, puede controlar y aumentar la serialización de objetos que se encuentran en una DLL, incluso si no tiene acceso al origen; en segundo lugar, puede crear un conjunto de clases serializables pero serializar los objetos de varias maneras.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. Por ejemplo, en lugar de serializar los miembros de una instancia de clase como elementos XML, se pueden serializar ellos como atributos XML, resultante en un documento más eficaz al transporte.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.

Después de crear un XmlAttributeOverrides objeto, pasarlo como argumento a la XmlSerializer constructor.After you create an XmlAttributeOverrides object, you pass it as an argument to the XmlSerializer constructor. Resultante XmlSerializer utiliza los datos incluidos en el XmlAttributeOverrides para reemplazar los atributos que controlan cómo se serializan los objetos.The resulting XmlSerializer uses the data contained by the XmlAttributeOverrides to override attributes that control how objects are serialized. Para lograr esto, el XmlAttributeOverrides contiene una colección de los tipos de objeto que se reemplazan, así como un XmlAttributes objeto asociado con cada tipo de objeto reemplazado.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. El XmlAttributes propio objeto contiene un conjunto apropiado de objetos de atributos que controlan cómo se serializa cada campo, propiedad o clase.The XmlAttributes object itself contains an appropriate set of attribute objects that control how each field, property, or class is serialized.

El proceso para crear y usar un XmlAttributeOverrides objeto es como sigue:The process for creating and using an XmlAttributeOverrides object is as follows:

  1. Crear un XmlAttributes objeto.Create an XmlAttributes object.

  2. Crear un objeto de atributo que sea adecuado para el objeto que se va a invalidar.Create an attribute object that is appropriate to the object being overridden. Por ejemplo, para reemplazar un campo o propiedad, cree un XmlElementAttribute, con el nuevo tipo derivado.For example, to override a field or property, create an XmlElementAttribute, using the new, derived type. Opcionalmente, puede asignar un nuevo ElementName, o Namespace que invalida el nombre de atributo o espacio de nombres de la clase base.You can optionally assign a new ElementName, or Namespace that overrides the base class's attribute name or namespace.

  3. Agregue el objeto de atributo correspondiente XmlAttributes propiedad o colección.Add the attribute object to the appropriate XmlAttributes property or collection. Por ejemplo, agregaría el XmlElementAttribute a la XmlElements colección de la XmlAttributes objeto, especificando el nombre del miembro que se está reemplazando.For example, you would add the XmlElementAttribute to the XmlElements collection of the XmlAttributes object, specifying the member name that is being overridden.

  4. Crear un XmlAttributeOverrides objeto.Create an XmlAttributeOverrides object.

  5. Mediante el Add método, agregue el XmlAttributes de objeto para el XmlAttributeOverrides objeto.Using the Add method, add the XmlAttributes object to the XmlAttributeOverrides object. Si el objeto que se va a reemplazar es un XmlRootAttribute o XmlTypeAttribute, solo tendrá que especificar el tipo de objeto reemplazado.If the object being overridden is an XmlRootAttribute or XmlTypeAttribute, you need only to specify the type of the overridden object. Pero si va a reemplazar un campo o propiedad, también debe especificar el nombre del miembro reemplazado.But if you are overriding a field or property, you must also specify the name of the overridden member.

  6. Al construir el XmlSerializer, pase el XmlAttributeOverrides a la XmlSerializer constructor.When constructing the XmlSerializer, pass the XmlAttributeOverrides to the XmlSerializer constructor.

  7. Usar resultante XmlSerializer para serializar o deserializar los objetos de clase derivada.Use the resulting XmlSerializer to serialize or deserialize the derived class objects.

Constructores

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

Inicializa una nueva instancia de la clase XmlAttributeOverrides.Initializes a new instance of the XmlAttributeOverrides class.

Propiedades

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

Obtiene el objeto asociado al tipo (de clase base) especificado.Gets the object associated with the specified (base-class) type. El parámetro de miembro especifica el miembro de clase base que se reemplaza.The member parameter specifies the base-class member that is overridden.

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

Obtiene el objeto asociado al tipo de clase base especificado.Gets the object associated with the specified, base-class, type.

Métodos

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

Agrega un objeto XmlAttributes a la colección de objetos XmlAttributes.Adds an XmlAttributes object to the collection of XmlAttributes objects. El parámetro type especifica un objeto que se va a reemplazar.The type parameter specifies an object to be overridden. El parámetro member especifica el nombre de un miembro que se va a reemplazar.The member parameter specifies the name of a member that is overridden.

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

Agrega un objeto XmlAttributes a la colección de objetos XmlAttributes.Adds an XmlAttributes object to the collection of XmlAttributes objects. El parámetro type especifica un objeto que va a ser reemplazado por el objeto XmlAttributes.The type parameter specifies an object to be overridden by the XmlAttributes object.

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

Determina si el objeto especificado es igual al objeto actual.Determines whether the specified object is equal to the current object.

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

Sirve como la función hash predeterminada.Serves as the default hash function.

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

Obtiene el Type de la instancia actual.Gets the Type of the current instance.

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

Crea una copia superficial del objeto Object actual.Creates a shallow copy of the current Object.

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

Devuelve una cadena que representa el objeto actual.Returns a string that represents the current object.

(Inherited from Object)

Se aplica a

Consulte también: