AsyncCompletedEventArgs.RaiseExceptionIfNecessary AsyncCompletedEventArgs.RaiseExceptionIfNecessary AsyncCompletedEventArgs.RaiseExceptionIfNecessary AsyncCompletedEventArgs.RaiseExceptionIfNecessary Method

Definition

Löst eine benutzerdefinierte Ausnahme aus, wenn bei einem asynchronen Vorgang ein Fehler aufgetreten ist.Raises a user-supplied exception if an asynchronous operation failed.

protected:
 void RaiseExceptionIfNecessary();
protected void RaiseExceptionIfNecessary ();
member this.RaiseExceptionIfNecessary : unit -> unit
Protected Sub RaiseExceptionIfNecessary ()

Ausnahmen

Die Error-Eigenschaft wurde durch den asynchronen Vorgang festgelegt.The Error property has been set by the asynchronous operation. Die InnerException-Eigenschaft enthält einen Verweis auf Error.The InnerException property holds a reference to Error.

Beispiele

Das folgende Codebeispiel veranschaulicht die Verwendung RaiseExceptionIfNecessary Eigenschaften der Klasse abgeleitet.The following code example demonstrates using RaiseExceptionIfNecessary in derived class properties.

public class CalculatePrimeCompletedEventArgs :
    AsyncCompletedEventArgs
{
    private int numberToTestValue = 0;
    private int firstDivisorValue = 1;
    private bool isPrimeValue;

    public CalculatePrimeCompletedEventArgs(
        int numberToTest,
        int firstDivisor,
        bool isPrime,
        Exception e,
        bool canceled,
        object state) : base(e, canceled, state)
    {
        this.numberToTestValue = numberToTest;
        this.firstDivisorValue = firstDivisor;
        this.isPrimeValue = isPrime;
    }

    public int NumberToTest
    {
        get
        {
            // Raise an exception if the operation failed or 
            // was canceled.
            RaiseExceptionIfNecessary();

            // If the operation was successful, return the 
            // property value.
            return numberToTestValue;
        }
    }

    public int FirstDivisor
    {
        get
        {
            // Raise an exception if the operation failed or 
            // was canceled.
            RaiseExceptionIfNecessary();

            // If the operation was successful, return the 
            // property value.
            return firstDivisorValue;
        }
    }

    public bool IsPrime
    {
        get
        {
            // Raise an exception if the operation failed or 
            // was canceled.
            RaiseExceptionIfNecessary();

            // If the operation was successful, return the 
            // property value.
            return isPrimeValue;
        }
    }
}

Public Class CalculatePrimeCompletedEventArgs
    Inherits AsyncCompletedEventArgs
    Private numberToTestValue As Integer = 0
    Private firstDivisorValue As Integer = 1
    Private isPrimeValue As Boolean


    Public Sub New( _
    ByVal numberToTest As Integer, _
    ByVal firstDivisor As Integer, _
    ByVal isPrime As Boolean, _
    ByVal e As Exception, _
    ByVal canceled As Boolean, _
    ByVal state As Object)

        MyBase.New(e, canceled, state)
        Me.numberToTestValue = numberToTest
        Me.firstDivisorValue = firstDivisor
        Me.isPrimeValue = isPrime

    End Sub


    Public ReadOnly Property NumberToTest() As Integer
        Get
            ' Raise an exception if the operation failed 
            ' or was canceled.
            RaiseExceptionIfNecessary()

            ' If the operation was successful, return 
            ' the property value.
            Return numberToTestValue
        End Get
    End Property


    Public ReadOnly Property FirstDivisor() As Integer
        Get
            ' Raise an exception if the operation failed 
            ' or was canceled.
            RaiseExceptionIfNecessary()

            ' If the operation was successful, return 
            ' the property value.
            Return firstDivisorValue
        End Get
    End Property


    Public ReadOnly Property IsPrime() As Boolean
        Get
            ' Raise an exception if the operation failed 
            ' or was canceled.
            RaiseExceptionIfNecessary()

            ' If the operation was successful, return 
            ' the property value.
            Return isPrimeValue
        End Get
    End Property
End Class

Hinweise für Vererber

Wenn Sie eine eigene Klasse von abgeleitet haben die AsyncCompletedEventArgs -Klasse, die schreibgeschützten Eigenschaften sollten Aufrufen der RaiseExceptionIfNecessary() Methode vor der Rückgabe den Wert der Eigenschaft.If you have derived your own class from the AsyncCompletedEventArgs class, your read-only properties should call the RaiseExceptionIfNecessary() method before returning the property value. Wenn die von der Komponente asynchrone weist Worker-Code eine Ausnahme der Error -Eigenschaft, oder legt ihn fest der Cancelled Eigenschaft true, die Eigenschaft wird eine Ausnahme ausgelöst, wenn ein Client versucht, dessen Wert zu lesen.If the component's asynchronous worker code assigns an exception to the Error property or sets the Cancelled property to true, the property will raise an exception if a client tries to read its value. Dadurch wird verhindert, dass Clients den Zugriff auf Eigenschaften, die möglicherweise nicht aufgrund eines Fehlers bei der asynchrone Vorgang gültig sind.This prevents clients from accessing properties that are potentially not valid due to a failure in the asynchronous operation.

Gilt für:

Siehe auch