XmlAttributes クラス

[アーティクル]
03/28/2008

XmlSerializer がオブジェクトをシリアル化および逆シリアル化する方法を制御する属性オブジェクトのコレクションを示します。

この型のすべてのメンバの一覧については、XmlAttributes メンバを参照してください。

System.Object
System.Xml.Serialization.XmlAttributes

Public Class XmlAttributes
[C#]
public class XmlAttributes
[C++]
public __gc class XmlAttributes
[JScript]
public class XmlAttributes

スレッドセーフ

この型の public static (Visual Basicでは Shared) のすべてのメンバは、マルチスレッド操作で安全に使用できます。インスタンスのメンバの場合は、スレッドセーフであるとは限りません。

解説

XmlAttributes の作成は、 XmlSerializer がクラスインスタンスをシリアル化する既定の方法をオーバーライドするプロセスの一部です。たとえば、アクセスできないソースを持つ DLL で作成されたオブジェクトをシリアル化するとします。 XmlAttributeOverrides を使用することにより、オブジェクトをシリアル化する別の方法を使用できたり、その他の制御を行うことができます。

XmlAttributes クラスのメンバは、シリアル化を制御する一連の属性クラスと直接的に対応します。たとえば、 XmlText プロパティを XmlTextAttribute に設定しておく必要があります。これにより XmlSerializer に対してプロパティ値を XML テキストとしてシリアル化するよう命令して、フィールドまたはプロパティのシリアル化をオーバーライドできます。シリアル化を制御する属性の全一覧については、 XmlSerializer のトピックを参照してください。

XmlAttributes クラスと共に XmlAttributeOverrides を使用する方法の詳細については、「 XML シリアル化のオーバーライド」を参照してください。

使用例

[Visual Basic, C#, C++] Orchestra という名前のクラスをシリアル化する例を次に示します。この例には、Instrument オブジェクトの配列を返す Instruments という名前の単一のフィールドが含まれています。Brass という名前の 2 番目のクラスが Instrument クラスから継承されます。この例では、 XmlAttributes オブジェクトを作成して Instrument フィールドをオーバーライドします。このオーバーライドにより、フィールドが Brass オブジェクトを受け入れるようにして、 XmlAttributes オブジェクトを XmlAttributeOverrides クラスのインスタンスに追加します。

 
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(ByVal 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 element to the collection of elements.
        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.ToString())
        Next i
    End Sub
End Class


[C#] 
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 element to the collection of elements.
      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);
      }
   }
}


[C++] 
#using <mscorlib.dll>
#using <System.Xml.dll>
#using <System.dll>
using namespace System;
using namespace System::IO;
using namespace System::Xml::Serialization;

public __gc class Instrument
{
public:
   String* Name;
};

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

public __gc class Orchestra
{
public:
   Instrument* Instruments[];
};   

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 = S"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), S"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 = S"Trumpet";
   i->IsValved = true;
   Instrument* myInstruments[] = {i};
   band->Instruments = myInstruments;

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

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 = S"Brass";
   attr->Type = __typeof(Brass);

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

   attrOverrides->Add(__typeof(Orchestra), S"Instruments", attrs);

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

   FileStream* fs = new FileStream(filename, FileMode::Open);
   Orchestra* band = dynamic_cast<Orchestra*> (s->Deserialize(fs));
   Console::WriteLine(S"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 = __try_cast<Instrument*>(myEnum->Current);
      b = dynamic_cast<Brass*>(i);
      Console::WriteLine(
         S"{0}\n{1}", b->Name, __box(b->IsValved));
   }
}

int main()
{
   SerializeObject(S"Override.xml");
   DeserializeObject(S"Override.xml");
}

[JScript] JScript のサンプルはありません。Visual Basic、C#、および C++ のサンプルを表示するには、このページの左上隅にある言語のフィルタボタンをクリックします。

必要条件

名前空間: System.Xml.Serialization

プラットフォーム: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 ファミリ

アセンブリ: System.Xml (System.Xml.dll 内)

参照

XmlAttributes メンバ | System.Xml.Serialization 名前空間 | XmlAttributeOverrides | XmlSerializer

次の方法で共有

XmlAttributes クラス

スレッドセーフ

解説

使用例

必要条件

参照

その他のリソース