Ich weiß, dass Dispose() für nicht verwaltete Ressourcen gedacht ist und die Ressource entsorgt werden sollte, wenn sie nicht mehr benötigt wird, ohne darauf zu warten, dass der Garbage Collector das Objekt finalisiert.
Wenn das Objekt jedoch entsorgt wird, wird die Finalisierung des Garbage Collectors unterdrückt (GC.SuppressFinalize(this); im folgenden Code). Das bedeutet, wenn das Objekt verwaltete Ressourcen enthält, müssen wir uns auch darum kümmern, da der Garbage Collector diese nicht aufräumt.
Im Beispielcode unten (aus MSDN) ist "Component" eine verwaltete Ressource, und wir rufen dispose() für diese Ressource auf (component.Dispose()). Meine Frage ist, wie implementieren wir diese Methode für die Klasse "Component", die eine verwaltete Ressource ist? Sollten wir etwas wie Collect() verwenden, um den Garbage Collector zu bitten, diesen Teil zu bereinigen?
Für jede Idee wären wir dankbar. Danke.
Nachfolgend finden Sie den Code, den ich mir ansehe und der von MSDN stammt:
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;
// 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.
}
}
