IAsyncResult Interfaccia

Definizione

Rappresenta lo stato di un'operazione asincrona.Represents the status of an asynchronous operation.

public interface class IAsyncResult
[System.Runtime.InteropServices.ComVisible(true)]
public interface IAsyncResult
type IAsyncResult = interface
Public Interface IAsyncResult
Derivato
Attributi

Esempi

Nell'esempio seguente viene illustrato come utilizzare la AsyncWaitHandle proprietà per ottenere un WaitHandleoggetto e come attendere la chiamata asincrona su un delegato.The following example demonstrates how to use the AsyncWaitHandle property to get a WaitHandle, and how to wait for an asynchronous call on a delegate. L'oggetto WaitHandle viene segnalato al completamento della chiamata asincrona ed è possibile attenderlo chiamando il metodo WaitOne .The WaitHandle is signaled when the asynchronous call completes, and you can wait for it by calling the WaitOne method.

L'esempio è costituito da due classi: la classe che contiene il metodo chiamato in modo asincrono e la classe che contiene il Main metodo che effettua la chiamata.The example consists of two classes: the class that contains the method that is called asynchronously, and the class that contains the Main method that makes the call.

Per ulteriori informazioni ed esempi relativi alla chiamata asincrona dei metodi mediante l'utilizzo di delegati, vedere chiamata asincrona dei metodi sincroni.For more information and more examples of calling methods asynchronously by using delegates, see Calling Synchronous Methods Asynchronously.

using namespace System;
using namespace System::Threading;
using namespace System::Runtime::InteropServices; 

namespace Examples {
namespace AdvancedProgramming {
namespace AsynchronousOperations
{
    public ref class AsyncDemo 
    {
    public:
        // The method to be executed asynchronously.
        String^ TestMethod(int callDuration, [OutAttribute] int% threadId) 
        {
            Console::WriteLine("Test method begins.");
            Thread::Sleep(callDuration);
            threadId = Thread::CurrentThread->ManagedThreadId;
            return String::Format("My call time was {0}.", callDuration);
        }
    };

    // The delegate must have the same signature as the method
    // it will call asynchronously.
    public delegate String^ AsyncMethodCaller(int callDuration, [OutAttribute] int% threadId);
}}}
using System;
using System.Threading; 

namespace Examples.AdvancedProgramming.AsynchronousOperations
{
    public class AsyncDemo 
    {
        // The method to be executed asynchronously.
        public string TestMethod(int callDuration, out int threadId) 
        {
            Console.WriteLine("Test method begins.");
            Thread.Sleep(callDuration);
            threadId = Thread.CurrentThread.ManagedThreadId;
            return String.Format("My call time was {0}.", callDuration.ToString());
        }
    }
    // The delegate must have the same signature as the method
    // it will call asynchronously.
    public delegate string AsyncMethodCaller(int callDuration, out int threadId);
}
Imports System.Threading
Imports System.Runtime.InteropServices 

Namespace Examples.AdvancedProgramming.AsynchronousOperations
    Public Class AsyncDemo 
        ' The method to be executed asynchronously.
        Public Function TestMethod(ByVal callDuration As Integer, _
                <Out> ByRef threadId As Integer) As String
            Console.WriteLine("Test method begins.")
            Thread.Sleep(callDuration)
            threadId = Thread.CurrentThread.ManagedThreadId()
            return String.Format("My call time was {0}.", callDuration.ToString())
        End Function
    End Class

    ' The delegate must have the same signature as the method
    ' it will call asynchronously.
    Public Delegate Function AsyncMethodCaller(ByVal callDuration As Integer, _
        <Out> ByRef threadId As Integer) As String
End Namespace
#using <TestMethod.dll>

using namespace System;
using namespace System::Threading;
using namespace Examples::AdvancedProgramming::AsynchronousOperations;

void main() 
{
    // The asynchronous method puts the thread id here.
    int threadId;

    // Create an instance of the test class.
    AsyncDemo^ ad = gcnew AsyncDemo();

    // Create the delegate.
    AsyncMethodCaller^ caller = gcnew AsyncMethodCaller(ad, &AsyncDemo::TestMethod);
       
    // Initiate the asychronous call.
    IAsyncResult^ result = caller->BeginInvoke(3000, 
        threadId, nullptr, nullptr);

    Thread::Sleep(0);
    Console::WriteLine("Main thread {0} does some work.",
        Thread::CurrentThread->ManagedThreadId);

    // Wait for the WaitHandle to become signaled.
    result->AsyncWaitHandle->WaitOne();

    // Perform additional processing here.
    // Call EndInvoke to retrieve the results.
    String^ returnValue = caller->EndInvoke(threadId, result);

    // Close the wait handle.
    result->AsyncWaitHandle->Close();

    Console::WriteLine("The call executed on thread {0}, with return value \"{1}\".",
        threadId, returnValue);
}

/* This example produces output similar to the following:

Main thread 1 does some work.
Test method begins.
The call executed on thread 3, with return value "My call time was 3000.".
 */
using System;
using System.Threading;

namespace Examples.AdvancedProgramming.AsynchronousOperations
{
    public class AsyncMain 
    {
        static void Main() 
        {
            // The asynchronous method puts the thread id here.
            int threadId;

            // Create an instance of the test class.
            AsyncDemo ad = new AsyncDemo();

            // Create the delegate.
            AsyncMethodCaller caller = new AsyncMethodCaller(ad.TestMethod);
       
            // Initiate the asychronous call.
            IAsyncResult result = caller.BeginInvoke(3000, 
                out threadId, null, null);

            Thread.Sleep(0);
            Console.WriteLine("Main thread {0} does some work.",
                Thread.CurrentThread.ManagedThreadId);

            // Wait for the WaitHandle to become signaled.
            result.AsyncWaitHandle.WaitOne();

            // Perform additional processing here.
            // Call EndInvoke to retrieve the results.
            string returnValue = caller.EndInvoke(out threadId, result);

            // Close the wait handle.
            result.AsyncWaitHandle.Close();

            Console.WriteLine("The call executed on thread {0}, with return value \"{1}\".",
                threadId, returnValue);
        }
    }
}

/* This example produces output similar to the following:

Main thread 1 does some work.
Test method begins.
The call executed on thread 3, with return value "My call time was 3000.".
 */
Imports System.Threading
Imports System.Runtime.InteropServices 

Namespace Examples.AdvancedProgramming.AsynchronousOperations

    Public Class AsyncMain 
        Shared Sub Main() 
            ' The asynchronous method puts the thread id here.
            Dim threadId As Integer

            ' Create an instance of the test class.
            Dim ad As New AsyncDemo()

            ' Create the delegate.
            Dim caller As New AsyncMethodCaller(AddressOf ad.TestMethod)
       
            ' Initiate the asynchronous call.
            Dim result As IAsyncResult = caller.BeginInvoke(3000, _
                threadId, Nothing, Nothing)

            Thread.Sleep(0)
            Console.WriteLine("Main thread {0} does some work.", _
                Thread.CurrentThread.ManagedThreadId)
            ' Perform additional processing here and then
            ' wait for the WaitHandle to be signaled.
            result.AsyncWaitHandle.WaitOne()

            ' Call EndInvoke to retrieve the results.
            Dim returnValue As String = caller.EndInvoke(threadId, result)

            ' Close the wait handle.
            result.AsyncWaitHandle.Close()

            Console.WriteLine("The call executed on thread {0}, with return value ""{1}"".", _
                threadId, returnValue)
        End Sub
    End Class
End Namespace

'This example produces output similar to the following:
'
'Main thread 1 does some work.
'Test method begins.
'The call executed on thread 3, with return value "My call time was 3000.".

Commenti

L' IAsyncResult interfaccia viene implementata da classi che contengono metodi che possono funzionare in modo asincrono.The IAsyncResult interface is implemented by classes containing methods that can operate asynchronously. Un'operazione asincrona viene iniziata dal tipo restituito dei metodi, ad esempio FileStream.BeginRead, e viene passata ai metodi che concludono un'operazione asincrona, ad esempio FileStream.EndRead.It is the return type of methods that initiate an asynchronous operation, such as FileStream.BeginRead, and it is passed to methods that conclude an asynchronous operation, such as FileStream.EndRead. IAsyncResultgli oggetti vengono passati anche ai metodi richiamati dai delegati al completamento di AsyncCallback un'operazione asincrona.IAsyncResult objects are also passed to methods invoked by AsyncCallback delegates when an asynchronous operation completes.

Un oggetto che supporta l' IAsyncResult interfaccia archivia le informazioni sullo stato per un'operazione asincrona e fornisce un oggetto di sincronizzazione per consentire la segnalazione dei thread al termine dell'operazione.An object that supports the IAsyncResult interface stores state information for an asynchronous operation and provides a synchronization object to allow threads to be signaled when the operation completes.

Nota

La AsyncResult classe è l'implementazione di IAsyncResult restituita dal BeginInvoke metodo quando si usa un delegato per chiamare un metodo in modo asincrono.The AsyncResult class is the implementation of IAsyncResult that is returned by the BeginInvoke method when you use a delegate to call a method asynchronously.

Per una descrizione dettagliata del modo in IAsyncResult cui viene usata l'interfaccia, vedere l'argomento chiamare metodi sincroni in modo asincrono .For a detailed description of how the IAsyncResult interface is used, see the Calling Synchronous Methods Asynchronously topic.

Proprietà

AsyncState

Ottiene un oggetto definito dall'utente qualificato per un'operazione asincrona o contenente informazioni relative a un'operazione asincrona.Gets a user-defined object that qualifies or contains information about an asynchronous operation.

AsyncWaitHandle

Ottiene un WaitHandle, utilizzato per attendere il completamento di un'operazione asincrona.Gets a WaitHandle that is used to wait for an asynchronous operation to complete.

CompletedSynchronously

Valore che indica se l'operazione asincrona. è stata completata in modo sincronoGets a value that indicates whether the asynchronous operation completed synchronously.

IsCompleted

Ottiene un valore che indica l'eventuale completamento dell'operazione asincrona.Gets a value that indicates whether the asynchronous operation has completed.

Si applica a