IDisposable IDisposable IDisposable IDisposable Interface

Definition

Stellt einen Mechanismus für die Freigabe nicht verwalteter Ressourcen bereit.Provides a mechanism for releasing unmanaged resources.

public interface class IDisposable
[System.Runtime.InteropServices.ComVisible(true)]
public interface IDisposable
type IDisposable = interface
Public Interface IDisposable
Abgeleitet
Attribute

Beispiele

Im folgende Beispiel wird veranschaulicht, wie eine Ressourcenklasse zu erstellen, implementiert die IDisposable Schnittstelle.The following example demonstrates how to create a resource class that implements the IDisposable interface.

#using <System.dll>
#using <System.Windows.Forms.dll>

using namespace System;
using namespace System::ComponentModel;
using namespace System::Windows::Forms;

// The following example demonstrates how to create a class that 
// implements the IDisposable interface and the IDisposable.Dispose
// method with finalization to clean up unmanaged resources. 
//
public ref class MyResource: public IDisposable
{
private:

   // Pointer to an external unmanaged resource.
   IntPtr handle;

   // A managed resource this class uses.
   Component^ component;

   // Track whether Dispose has been called.
   bool disposed;

public:
   // The class constructor.
   MyResource( IntPtr handle, Component^ component )
   {
      this->handle = handle;
      this->component = component;
      disposed = false;
   }

   // This method is called if the user explicitly disposes of the
   // object (by calling the Dispose method in other managed languages, 
   // or the destructor in C++). The compiler emits as a call to 
   // GC::SuppressFinalize( this ) for you, so there is no need to 
   // call it here.
   ~MyResource() 
   {
      // Dispose of managed resources.
      component->~Component();

      // Call C++ finalizer to clean up unmanaged resources.
      this->!MyResource();

      // Mark the class as disposed. This flag allows you to throw an
      // exception if a disposed object is accessed.
      disposed = true;
   }

   // Use interop to call the method necessary to clean up the 
   // unmanaged resource.
   //
   [System::Runtime::InteropServices::DllImport("Kernel32")]
   static Boolean CloseHandle( IntPtr handle );

   // The C++ finalizer destructor ensures that unmanaged resources get
   // released if the user releases the object without explicitly 
   // disposing of it.
   //
   !MyResource()
   {      
      // Call the appropriate methods to clean up unmanaged 
      // resources here. If disposing is false when Dispose(bool,
      // disposing) is called, only the following code is executed.
      CloseHandle( handle );
      handle = IntPtr::Zero;
   }

};

void main()
{
   // Insert code here to create and use the MyResource object.
   MyResource^ mr = gcnew MyResource((IntPtr) 42, (Component^) gcnew Button());
   mr->~MyResource();
}
using System;
using System.ComponentModel;

// The following example demonstrates how to create
// a resource class that implements the IDisposable interface
// and the IDisposable.Dispose method.

public class DisposeExample
{
    // A base class that implements IDisposable.
    // By implementing IDisposable, you are announcing that
    // instances of this type allocate scarce resources.
    public class MyResource: IDisposable
    {
        // Pointer to an external unmanaged resource.
        private IntPtr handle;
        // Other managed resource this class uses.
        private Component component = new Component();
        // Track whether Dispose has been called.
        private bool disposed = false;

        // The class constructor.
        public MyResource(IntPtr handle)
        {
            this.handle = handle;
        }

        // Implement IDisposable.
        // Do not make this method virtual.
        // A derived class should not be able to override this method.
        public void Dispose()
        {
            Dispose(true);
            // This object will be cleaned up by the Dispose method.
            // Therefore, you should call GC.SupressFinalize to
            // take this object off the finalization queue
            // and prevent finalization code for this object
            // from executing a second time.
            GC.SuppressFinalize(this);
        }

        // Dispose(bool disposing) executes in two distinct scenarios.
        // If disposing equals true, the method has been called directly
        // or indirectly by a user's code. Managed and unmanaged resources
        // can be disposed.
        // If disposing equals false, the method has been called by the
        // runtime from inside the finalizer and you should not reference
        // other objects. Only unmanaged resources can be disposed.
        protected virtual void Dispose(bool disposing)
        {
            // Check to see if Dispose has already been called.
            if(!this.disposed)
            {
                // If disposing equals true, dispose all managed
                // and unmanaged resources.
                if(disposing)
                {
                    // Dispose managed resources.
                    component.Dispose();
                }

                // Call the appropriate methods to clean up
                // unmanaged resources here.
                // If disposing is false,
                // only the following code is executed.
                CloseHandle(handle);
                handle = IntPtr.Zero;

                // Note disposing has been done.
                disposed = true;

            }
        }

        // Use interop to call the method necessary
        // to clean up the unmanaged resource.
        [System.Runtime.InteropServices.DllImport("Kernel32")]
        private extern static Boolean CloseHandle(IntPtr handle);

        // Use C# destructor syntax for finalization code.
        // This destructor will run only if the Dispose method
        // does not get called.
        // It gives your base class the opportunity to finalize.
        // Do not provide destructors in types derived from this class.
        ~MyResource()
        {
            // Do not re-create Dispose clean-up code here.
            // Calling Dispose(false) is optimal in terms of
            // readability and maintainability.
            Dispose(false);
        }
    }
    public static void Main()
    {
        // Insert code here to create
        // and use the MyResource object.
    }
}
Imports System
Imports System.ComponentModel

' The following example demonstrates how to create
' a resource class that implements the IDisposable interface
' and the IDisposable.Dispose method.
Public Class DisposeExample

   ' A class that implements IDisposable.
   ' By implementing IDisposable, you are announcing that 
   ' instances of this type allocate scarce resources.
   Public Class MyResource
      Implements IDisposable
      ' Pointer to an external unmanaged resource.
      Private handle As IntPtr
      ' Other managed resource this class uses.
      Private component As component
      ' Track whether Dispose has been called.
      Private disposed As Boolean = False

      ' The class constructor.
      Public Sub New(ByVal handle As IntPtr)
         Me.handle = handle
      End Sub

      ' Implement IDisposable.
      ' Do not make this method virtual.
      ' A derived class should not be able to override this method.
      Public Overloads Sub Dispose() Implements IDisposable.Dispose
         Dispose(True)
         ' This object will be cleaned up by the Dispose method.
         ' Therefore, you should call GC.SupressFinalize to
         ' take this object off the finalization queue 
         ' and prevent finalization code for this object
         ' from executing a second time.
         GC.SuppressFinalize(Me)
      End Sub

      ' Dispose(bool disposing) executes in two distinct scenarios.
      ' If disposing equals true, the method has been called directly
      ' or indirectly by a user's code. Managed and unmanaged resources
      ' can be disposed.
      ' If disposing equals false, the method has been called by the 
      ' runtime from inside the finalizer and you should not reference 
      ' other objects. Only unmanaged resources can be disposed.
      Protected Overridable Overloads Sub Dispose(ByVal disposing As Boolean)
         ' Check to see if Dispose has already been called.
         If Not Me.disposed Then
            ' If disposing equals true, dispose all managed 
            ' and unmanaged resources.
            If disposing Then
               ' Dispose managed resources.
               component.Dispose()
            End If

            ' Call the appropriate methods to clean up 
            ' unmanaged resources here.
            ' If disposing is false, 
            ' only the following code is executed.
            CloseHandle(handle)
            handle = IntPtr.Zero

            ' Note disposing has been done.
            disposed = True

         End If
      End Sub

      ' Use interop to call the method necessary  
      ' to clean up the unmanaged resource.
      <System.Runtime.InteropServices.DllImport("Kernel32")> _
      Private Shared Function CloseHandle(ByVal handle As IntPtr) As [Boolean]
      End Function

      ' This finalizer will run only if the Dispose method 
      ' does not get called.
      ' It gives your base class the opportunity to finalize.
      ' Do not provide finalize methods in types derived from this class.
      Protected Overrides Sub Finalize()
         ' Do not re-create Dispose clean-up code here.
         ' Calling Dispose(false) is optimal in terms of
         ' readability and maintainability.
         Dispose(False)
         MyBase.Finalize()
      End Sub
   End Class

   Public Shared Sub Main()
      ' Insert code here to create
      ' and use the MyResource object.
   End Sub

End Class

Hinweise

Der primäre Verwendungszweck dieser Schnittstelle werden nicht verwaltete Ressourcen freizugeben.The primary use of this interface is to release unmanaged resources. Die Speichermenge für ein verwaltetes Objekt, wenn das Objekt nicht mehr verwendet wird wird von der Garbage Collector automatisch freigegeben.The garbage collector automatically releases the memory allocated to a managed object when that object is no longer used. Allerdings ist es nicht möglich, um vorherzusagen, wann die automatische speicherbereinigung ausgeführt wird.However, it is not possible to predict when garbage collection will occur. Darüber hinaus der Garbage Collector hat keine Kenntnis von nicht verwalteten Ressourcen wie z. B. Fensterhandles, oder Öffnen von Dateien und Streams.Furthermore, the garbage collector has no knowledge of unmanaged resources such as window handles, or open files and streams.

Verwenden der Dispose -Methode dieser Schnittstelle explizit nicht verwaltete Ressourcen in Verbindung mit dem Garbage Collector freigegeben.Use the Dispose method of this interface to explicitly release unmanaged resources in conjunction with the garbage collector. Der Consumer eines Objekts kann diese Methode aufrufen, wenn das Objekt nicht mehr benötigt wird.The consumer of an object can call this method when the object is no longer needed.

Warnung

Es ist eine wichtige Änderung zum Hinzufügen der IDisposable Schnittstelle zu einer vorhandenen Klasse.It is a breaking change to add the IDisposable interface to an existing class. Da Sie bereits vorhandene Consumer Ihres Typs nicht aufrufen können Dispose, Sie nicht sicher, dass nicht verwaltete Ressourcen frei, die den Typ freigegeben werden.Because pre-existing consumers of your type cannot call Dispose, you cannot be certain that unmanaged resources held by your type will be released.

Da die IDisposable.Dispose Implementierung wird vom Consumer eines Typs aufgerufen, wenn die Ressourcen, die im Besitz von einer Instanz nicht mehr benötigt werden, Sie sollten entweder das verwaltete Objekt in ein SafeHandle (empfohlen), oder Sie sollten überschreibenObject.Finalizeauf nicht verwaltete Ressourcen freizugeben, wenn der Consumer vergisst, aufzurufen Dispose.Because the IDisposable.Dispose implementation is called by the consumer of a type when the resources owned by an instance are no longer needed, you should either wrap the managed object in a SafeHandle (the recommended alternative), or you should override Object.Finalize to free unmanaged resources in the event that the consumer forgets to call Dispose.

Wichtig

In .NET Framework, der C++-Compiler unterstützt die deterministische Verwerfen von Ressourcen, und lässt sich nicht auf die direkte Implementierung der der Dispose Methode.In the .NET Framework, the C++ compiler supports deterministic disposal of resources and does not allow direct implementation of the Dispose method.

Ausführliche Informationen dazu, wie diese Schnittstelle und die Object.Finalize Methode verwendet werden, finden Sie unter den Garbage Collection und Implementieren einer Dispose-Methode Themen.For a detailed discussion about how this interface and the Object.Finalize method are used, see the Garbage Collection and Implementing a Dispose Method topics.

Mithilfe eines Objekts, die IDisposable implementiertUsing an object that implements IDisposable

Wenn Ihre app einfach auf ein Objekt verwendet, die implementiert die IDisposable -Schnittstelle, rufen Sie die Objekteigenschaften IDisposable.Dispose Implementierung, wenn Sie mit der sie fertig sind.If your app simply uses an object that implements the IDisposable interface, you should call the object's IDisposable.Dispose implementation when you are finished using it. Abhängig von der Programmiersprache können Sie dies in zwei Arten ausführen:Depending on your programming language, you can do this in one of two ways:

  • Erstellen Sie mithilfe einer Sprache wie z. B. die using -Anweisung in C# und Visual Basic.By using a language construct such as the using statement in C# and Visual Basic.

  • Durch Umschließen des Aufrufs von der IDisposable.Dispose -Implementierung in einer try / finally Block.By wrapping the call to the IDisposable.Dispose implementation in a try/finally block.

Hinweis

Dokumentation für Typen implementiert IDisposable Beachten Sie den Umstand und enthalten eine Erinnerung zum Aufrufen der Dispose Implementierung.Documentation for types that implement IDisposable note that fact and include a reminder to call its Dispose implementation.

Die Anweisung von C# und Visual Basic verwendenThe C# and Visual Basic Using statement

Wenn Ihre Sprache ein Konstrukt, z. B. unterstützt die mit -Anweisung in C# und die Using -Anweisung in Visual Basic, können Sie sie explizit aufrufen IDisposable.Dispose selbst.If your language supports a construct such as the using statement in C# and the Using statement in Visual Basic, you can use it instead of explicitly calling IDisposable.Dispose yourself. Im folgenden Beispiel wird dieser Ansatz bei der Definition einer WordCount -Klasse, die Informationen zu einer Datei und die Anzahl der Wörter in den es beibehält.The following example uses this approach in defining a WordCount class that preserves information about a file and the number of words in it.

using System;
using System.IO;
using System.Text.RegularExpressions;

public class WordCount
{
   private String filename = String.Empty;
   private int nWords = 0;
   private String pattern = @"\b\w+\b"; 

   public WordCount(string filename)
   {
      if (! File.Exists(filename))
         throw new FileNotFoundException("The file does not exist.");
      
      this.filename = filename;
      string txt = String.Empty;
      using (StreamReader sr = new StreamReader(filename)) {
         txt = sr.ReadToEnd();
      }
      nWords = Regex.Matches(txt, pattern).Count;
   }
   
   public string FullName
   { get { return filename; } }
   
   public string Name
   { get { return Path.GetFileName(filename); } }
   
   public int Count 
   { get { return nWords; } }
}   
Imports System.IO
Imports System.Text.RegularExpressions

Public Class WordCount
   Private filename As String
   Private nWords As Integer
   Private pattern As String = "\b\w+\b" 

   Public Sub New(filename As String)
      If Not File.Exists(filename) Then
         Throw New FileNotFoundException("The file does not exist.")
      End If   
      
      Me.filename = filename
      Dim txt As String = String.Empty
      Using sr As New StreamReader(filename)
         txt = sr.ReadToEnd()
      End Using
      nWords = Regex.Matches(txt, pattern).Count
   End Sub
   
   Public ReadOnly Property FullName As String
      Get
         Return filename
      End Get   
   End Property
   
   Public ReadOnly Property Name As String
      Get
         Return Path.GetFileName(filename)
      End Get   
   End Property
   
   Public ReadOnly Property Count As Integer
      Get
         Return nWords
      End Get
   End Property
End Class

Die using -Anweisung ist tatsächlich ein syntaktisches Hilfsmittel.The using statement is actually a syntactic convenience. Zum Zeitpunkt der Kompilierung des Sprachcompilers implementiert die intermediate Language (IL) für eine try / finally Block.At compile time, the language compiler implements the intermediate language (IL) for a try/finally block.

Weitere Informationen zu den using -Anweisung finden Sie unter den Using-Anweisung oder using-Anweisung Themen.For more information about the using statement, see the Using Statement or using Statement topics.

Der Try/Finally-blockThe Try/Finally block

Wenn Ihre Programmiersprache ein Konstrukt, z. B. nicht unterstützt wird die using -Anweisung in C# oder Visual Basic, oder wenn Sie nicht verwenden möchten, rufen Sie die IDisposable.Dispose Implementierung von der finally -Block eine try / finally Anweisung.If your programming language does not support a construct like the using statement in C# or Visual Basic, or if you prefer not to use it, you can call the IDisposable.Dispose implementation from the finally block of a try/finally statement. Im folgenden Beispiel ersetzt die using blockieren, die im vorherigen Beispiel mit einem try / finally Block.The following example replaces the using block in the previous example with a try/finally block.

using System;
using System.IO;
using System.Text.RegularExpressions;

public class WordCount
{
   private String filename = String.Empty;
   private int nWords = 0;
   private String pattern = @"\b\w+\b"; 

   public WordCount(string filename)
   {
      if (! File.Exists(filename))
         throw new FileNotFoundException("The file does not exist.");
      
      this.filename = filename;
      string txt = String.Empty;
      StreamReader sr = null;
      try {
         sr = new StreamReader(filename);
         txt = sr.ReadToEnd();
      }
      finally {
         if (sr != null) sr.Dispose();     
      }
      nWords = Regex.Matches(txt, pattern).Count;
   }
   
   public string FullName
   { get { return filename; } }
   
   public string Name
   { get { return Path.GetFileName(filename); } }
   
   public int Count 
   { get { return nWords; } }
}   
Imports System.IO
Imports System.Text.RegularExpressions

Public Class WordCount
   Private filename As String
   Private nWords As Integer
   Private pattern As String = "\b\w+\b" 

   Public Sub New(filename As String)
      If Not File.Exists(filename) Then
         Throw New FileNotFoundException("The file does not exist.")
      End If   
      
      Me.filename = filename
      Dim txt As String = String.Empty
      Dim sr As StreamReader = Nothing
      Try
         sr = New StreamReader(filename)
         txt = sr.ReadToEnd()
      Finally
         If sr IsNot Nothing Then sr.Dispose() 
      End Try
      nWords = Regex.Matches(txt, pattern).Count
   End Sub
   
   Public ReadOnly Property FullName As String
      Get
         Return filename
      End Get   
   End Property
   
   Public ReadOnly Property Name As String
      Get
         Return Path.GetFileName(filename)
      End Get   
   End Property
   
   Public ReadOnly Property Count As Integer
      Get
         Return nWords
      End Get
   End Property
End Class

Weitere Informationen zu den try / finally Muster, finden Sie unter testen... Catch... Finally-Anweisung, Try-finally-, oder Try-finally-Anweisung.For more information about the try/finally pattern, see Try...Catch...Finally Statement, try-finally, or try-finally Statement.

Implementieren von IDisposableImplementing IDisposable

Implementieren Sie IDisposable nur dann, wenn der Typ nicht verwaltete Ressourcen direkt verwendet.You should implement IDisposable only if your type uses unmanaged resources directly. Der Consumer Ihres Typs können aufrufen Ihrer IDisposable.Dispose Implementierung, die Ressourcen freizugeben, wenn die Instanz nicht mehr benötigt wird.The consumers of your type can call your IDisposable.Dispose implementation to free resources when the instance is no longer needed. Um Fälle zu behandeln, in dem sie nicht aufrufen Dispose, sollten Sie entweder eine Klasse abgeleitete SafeHandle , die nicht verwalteten Ressourcen, oder Sie umschließen überschreiben, sollte die Object.Finalize -Methode für einen Verweistyp handelt.To handle cases in which they fail to call Dispose, you should either use a class derived from SafeHandle to wrap the unmanaged resources, or you should override the Object.Finalize method for a reference type. In beiden Fällen verwenden Sie die Dispose Methode, um zu den Cleanup erforderlich ist, nach der Verwendung von nicht verwalteten Ressourcen, z. B. Freigabe, Freigabe oder das Zurücksetzen von nicht verwalteten Ressourcen.In either case, you use the Dispose method to perform whatever cleanup is necessary after using the unmanaged resources, such as freeing, releasing, or resetting the unmanaged resources.

Wichtig

Eine Basisklasse zu definieren, die nicht verwaltete Ressourcen verwendet und, die entweder hat, oder ist wahrscheinlich, Unterklassen, die entfernt werden sollen, sollten Sie implementieren die IDisposable.Dispose Methode, und geben Sie eine zweite Überladung von Dispose, wie dies in den nächsten Abschnitt.If you are defining a base class that uses unmanaged resources and that either has, or is likely to have, subclasses that should be disposed, you should implement the IDisposable.Dispose method and provide a second overload of Dispose, as discussed in the next section.

"IDisposable" und der VererbungshierarchieIDisposable and the inheritance hierarchy

Eine Basisklasse mit verwerfbaren Unterklassen sollten muss implementieren IDisposable wie folgt.A base class with subclasses that should be disposable must implement IDisposable as follows. Sie sollten dieses Muster verwenden, wann immer Sie implementieren IDisposable , die nicht in einem beliebigen sealed (NotInheritable in Visual Basic).You should use this pattern whenever you implement IDisposable on any type that isn't sealed (NotInheritable in Visual Basic).

  • Es sollte eine öffentliche, nicht virtuelle bereitstellen Dispose() -Methode sowie eine geschützte virtuelle Dispose(Boolean disposing) Methode.It should provide one public, non-virtual Dispose() method and a protected virtual Dispose(Boolean disposing) method.

  • Die Dispose() Methodenaufruf muss Dispose(true) und -Einrichtung für die Leistung sollte unterdrückt werden.The Dispose() method must call Dispose(true) and should suppress finalization for performance.

  • Der Basistyp sollte keine Finalizer enthalten.The base type should not include any finalizers.

Das folgende Codefragment gibt des löschmusters für Basisklassen.The following code fragment reflects the dispose pattern for base classes. Es wird davon ausgegangen, dass der Typ nicht überschreibt die Object.Finalize Methode.It assumes that your type does not override the Object.Finalize method.

using Microsoft.Win32.SafeHandles;
using System;
using System.Runtime.InteropServices;

class BaseClass : IDisposable
{
   // Flag: Has Dispose already been called?
   bool disposed = false;
   // Instantiate a SafeHandle instance.
   SafeHandle handle = new SafeFileHandle(IntPtr.Zero, true);
   
   // Public implementation of Dispose pattern callable by consumers.
   public void Dispose()
   { 
      Dispose(true);
      GC.SuppressFinalize(this);           
   }
   
   // Protected implementation of Dispose pattern.
   protected virtual void Dispose(bool disposing)
   {
      if (disposed)
         return; 
      
      if (disposing) {
         handle.Dispose();
         // Free any other managed objects here.
         //
      }
      
      disposed = true;
   }
}
Imports Microsoft.Win32.SafeHandles
Imports System.Runtime.InteropServices

Class BaseClass : Implements IDisposable
   ' Flag: Has Dispose already been called?
   Dim disposed As Boolean = False
   ' Instantiate a SafeHandle instance.
   Dim handle As SafeHandle = New SafeFileHandle(IntPtr.Zero, True)

   ' Public implementation of Dispose pattern callable by consumers.
   Public Sub Dispose() _
              Implements IDisposable.Dispose
      Dispose(True)
      GC.SuppressFinalize(Me)           
   End Sub
   
   ' Protected implementation of Dispose pattern.
   Protected Overridable Sub Dispose(disposing As Boolean)
      If disposed Then Return
      
      If disposing Then
         handle.Dispose()
         ' Free any other managed objects here.
         '
      End If
      
      disposed = True
   End Sub
End Class

Wenn Sie außer Kraft setzen der Object.Finalize -Methode sollte das folgende Muster in der Klasse implementiert.If you do override the Object.Finalize method, your class should implement the following pattern.

using System;

class BaseClass : IDisposable
{
   // Flag: Has Dispose already been called?
   bool disposed = false;
   
   // Public implementation of Dispose pattern callable by consumers.
   public void Dispose()
   { 
      Dispose(true);
      GC.SuppressFinalize(this);           
   }
   
   // Protected implementation of Dispose pattern.
   protected virtual void Dispose(bool disposing)
   {
      if (disposed)
         return; 
      
      if (disposing) {
         // Free any other managed objects here.
         //
      }
      
      // Free any unmanaged objects here.
      //
      disposed = true;
   }

   ~BaseClass()
   {
      Dispose(false);
   }
}
Class BaseClass : Implements IDisposable
   ' Flag: Has Dispose already been called?
   Dim disposed As Boolean = False
   
   ' Public implementation of Dispose pattern callable by consumers.
   Public Sub Dispose() _
              Implements IDisposable.Dispose
      Dispose(True)
      GC.SuppressFinalize(Me)           
   End Sub
   
   ' Protected implementation of Dispose pattern.
   Protected Overridable Sub Dispose(disposing As Boolean)
      If disposed Then Return
      
      If disposing Then
         ' Free any other managed objects here.
         '
      End If
      
      ' Free any unmanaged objects here.
      '
      disposed = True
   End Sub

   Protected Overrides Sub Finalize()
      Dispose(False)      
   End Sub
End Class

Unterklassen sollten das verwerfbare Muster wie folgt implementieren:Subclasses should implement the disposable pattern as follows:

  • Sie müssen Dispose(Boolean) überschreiben und die Basisklassen-Dispose(Boolean)-Implementierung aufrufen.They must override Dispose(Boolean) and call the base class Dispose(Boolean) implementation.

  • Sie können bei Bedarf einen Finalizer bereitstellen.They can provide a finalizer if needed. Der Finalizer muss Dispose(false) aufrufen.The finalizer must call Dispose(false).

Beachten Sie, dass abgeleitete Klassen nicht selbst implementieren die IDisposable -Schnittstelle und enthalten keine parameterlose Dispose Methode.Note that derived classes do not themselves implement the IDisposable interface and do not include a parameterless Dispose method. Sie wird nur der Basisklasse überschreiben Dispose(Boolean) Methode.They only override the base class Dispose(Boolean) method.

Das folgende Codefragment gibt das Dispose-Muster für abgeleitete Klassen.The following code fragment reflects the dispose pattern for derived classes. Es wird davon ausgegangen, dass der Typ nicht überschreibt die Object.Finalize Methode.It assumes that your type does not override the Object.Finalize method.

using Microsoft.Win32.SafeHandles;
using System;
using System.Runtime.InteropServices;

class DerivedClass : BaseClass
{
   // Flag: Has Dispose already been called?
   bool disposed = false;
   // Instantiate a SafeHandle instance.
   SafeHandle handle = new SafeFileHandle(IntPtr.Zero, true);

   // Protected implementation of Dispose pattern.
   protected override void Dispose(bool disposing)
   {
      if (disposed)
         return; 
      
      if (disposing) {
         handle.Dispose();
         // Free any other managed objects here.
         //
      }
      
      // Free any unmanaged objects here.
      //

      disposed = true;
      // Call base class implementation.
      base.Dispose(disposing);
   }
}
Imports Microsoft.Win32.SafeHandles
Imports System.Runtime.InteropServices

Class DerivedClass : Inherits BaseClass 
   ' Flag: Has Dispose already been called?
   Dim disposed As Boolean = False
   ' Instantiate a SafeHandle instance.
   Dim handle As SafeHandle = New SafeFileHandle(IntPtr.Zero, True)

   ' Protected implementation of Dispose pattern.
   Protected Overrides Sub Dispose(disposing As Boolean)
      If disposed Then Return
      
      If disposing Then
         handle.Dispose()
         ' Free any other managed objects here.
         '
      End If
      
      ' Free any unmanaged objects here.
      '
      disposed = True
      
      ' Call base class implementation.
      MyBase.Dispose(disposing)
   End Sub
End Class

Methoden

Dispose() Dispose() Dispose() Dispose()

Führt anwendungsspezifische Aufgaben durch, die mit der Freigabe, der Zurückgabe oder dem Zurücksetzen von nicht verwalteten Ressourcen zusammenhängen.Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.

Gilt für:

Siehe auch