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AsyncCompletedEventArgs.RaiseExceptionIfNecessary Método

  • Referencia

Definición

Espacio de nombres:
System.ComponentModel
Ensamblado:
System.ComponentModel.EventBasedAsync.dll
Ensamblado:
System.dll
Ensamblado:
netstandard.dll
Source:
AsyncCompletedEvent.cs
Source:
AsyncCompletedEvent.cs
Source:
AsyncCompletedEvent.cs

Genera una excepción proporcionada por el usuario si se ha producido un error en una operación asincrónica.

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

Excepciones

InvalidOperationException

La propiedad Cancelled es true.

TargetInvocationException

La operación asincrónica ha establecido la propiedad Error. La propiedad InnerException contiene una referencia a Error.

Ejemplos

En el ejemplo de código siguiente se muestra el uso RaiseExceptionIfNecessary de en propiedades de clase derivadas.

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

Notas a los desarrolladores de herederos

Si ha derivado su propia clase de la AsyncCompletedEventArgs clase , las propiedades de solo lectura deben llamar al RaiseExceptionIfNecessary() método antes de devolver el valor de propiedad. Si el código de trabajo asincrónico del componente asigna una excepción a la Error propiedad o establece la Cancelled propiedad trueen , la propiedad generará una excepción si un cliente intenta leer su valor. Esto impide que los clientes accedan a las propiedades que potencialmente no son válidas debido a un error en la operación asincrónica.

Se aplica a

Consulte también