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IDisposable-Schnittstelle

Definiert eine Methode zur Freigabe von reservierten, nicht verwalteten Ressourcen.

Namespace: System
Assembly: mscorlib (in mscorlib.dll)

[ComVisibleAttribute(true)] 
public interface IDisposable
/** @attribute ComVisibleAttribute(true) */ 
public interface IDisposable
ComVisibleAttribute(true) 
public interface IDisposable

Der Garbage Collector gibt automatisch den für ein verwaltetes Objekt reservierten Speicher frei, wenn dieses Objekt nicht mehr verwendet wird. Es kann allerdings nicht vorausgesagt werden, wann die Garbage Collection stattfindet. Darüber hinaus hat der Gargabe Collector keine Kenntnis von nicht verwalteten Ressourcen wie Fensterhandles oder offenen Dateien und Streams.

Mit der Dispose-Methode dieser Schnittstelle können nicht verwaltete Ressourcen in Verbindung mit dem Garbage Collector explizit freigegeben werden. Der Consumer eines Objekts kann diese Methode aufrufen, wenn das Objekt nicht mehr benötigt wird.

HinweisWichtig:

C++-Programmierer sollten Destructors and Finalizers in Visual C++ lesen. In .NET Framework, Version 2.0, unterstützt der C++-Compiler das Implementieren der deterministischen Freigabe von Ressourcen und verhindert das direkte Implementieren der Dispose-Methode.

Das Hinzufügen der IDisposable-Schnittstelle zu einer vorhandenen Klasse verlässt die Version, da es die Semantik der Klasse ändert.

Eine ausführliche Beschreibung der Verwendung dieser Schnittstelle und der Object.Finalize-Methode finden Sie unter den Themen zu Garbage Collection und Implementieren einer Dispose-Methode.

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.
        private 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;			
            }
            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.   
    }
}

import System.*;
import 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 static class MyResource implements 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 boolean disposed = false;

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

        // 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

        // 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.
        private void Dispose(boolean 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;
            }
            disposed = true;
        } //Dispose

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

        // Use J# 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.
        public void finalize() 
        {
            // Do not re-create Dispose clean-up code here.
            // Calling Dispose(false) is optimal in terms of
            // readability and maintainability.
            Dispose(false);
            try {
                super.finalize();
            }
            catch(System.Exception e ) {
            }
        } //finalize
    } //MyResource   
   
    public static void main(String[] args)
    {
        // Insert code here to create
        // and use the MyResource object.      
    } //main
} //DisposeExample 

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile für Pocket PC, Windows Mobile für Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.

.NET Framework

Unterstützt in: 2.0, 1.1, 1.0

.NET Compact Framework

Unterstützt in: 2.0, 1.0
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