MessageQueue.PeekCompleted Evento
Definição
Importante
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Ocorre quando uma mensagem é lida sem ser removida da fila. Este é o resultado da operação assíncrona, BeginPeek().
public:
event System::Messaging::PeekCompletedEventHandler ^ PeekCompleted;[System.Messaging.MessagingDescription("MQ_PeekCompleted")]
public event System.Messaging.PeekCompletedEventHandler PeekCompleted;[<System.Messaging.MessagingDescription("MQ_PeekCompleted")>]
member this.PeekCompleted : System.Messaging.PeekCompletedEventHandler Public Custom Event PeekCompleted As PeekCompletedEventHandler Tipo de evento
- Atributos
Exemplos
O exemplo de código a seguir cria um manipulador de eventos chamado MyPeekCompleted, o anexa ao delegado do PeekCompleted manipulador de eventos e chama BeginPeek para iniciar uma operação de espiada assíncrona na fila localizada no caminho ".\myQueue". Quando um PeekCompleted evento é acionado, o exemplo espia a mensagem e grava seu corpo na tela. O exemplo chama BeginPeek novamente para iniciar uma nova operação de espiada assíncrona
#using <system.dll>
#using <system.messaging.dll>
using namespace System;
using namespace System::Messaging;
// This example performs asynchronous peek operation
// processing.
//*************************************************
ref class MyNewQueue
{
public:
// Provides an event handler for the PeekCompleted
// event.
static void MyPeekCompleted( Object^ source, PeekCompletedEventArgs^ asyncResult )
{
// Connect to the queue.
MessageQueue^ mq = dynamic_cast<MessageQueue^>(source);
// End the asynchronous peek operation.
Message^ m = mq->EndPeek( asyncResult->AsyncResult );
// Display message information on the screen.
Console::WriteLine( "Message: {0}", static_cast<String^>(m->Body) );
// Restart the asynchronous peek operation.
mq->BeginPeek();
return;
}
};
// Provides an entry point into the application.
//
int main()
{
// Create an instance of MessageQueue. Set its formatter.
MessageQueue^ myQueue = gcnew MessageQueue( ".\\myQueue" );
array<Type^>^p = gcnew array<Type^>(1);
p[ 0 ] = String::typeid;
myQueue->Formatter = gcnew XmlMessageFormatter( p );
// Add an event handler for the PeekCompleted event.
myQueue->PeekCompleted += gcnew PeekCompletedEventHandler( MyNewQueue::MyPeekCompleted );
// Begin the asynchronous peek operation.
myQueue->BeginPeek();
// Do other work on the current thread.
return 0;
}
using System;
using System.Messaging;
namespace MyProject
{
/// <summary>
/// Provides a container class for the example.
/// </summary>
public class MyNewQueue
{
//**************************************************
// Provides an entry point into the application.
//
// This example performs asynchronous peek operation
// processing.
//**************************************************
public static void Main()
{
// Create an instance of MessageQueue. Set its formatter.
MessageQueue myQueue = new MessageQueue(".\\myQueue");
myQueue.Formatter = new XmlMessageFormatter(new Type[]
{typeof(String)});
// Add an event handler for the PeekCompleted event.
myQueue.PeekCompleted += new
PeekCompletedEventHandler(MyPeekCompleted);
// Begin the asynchronous peek operation.
myQueue.BeginPeek();
// Do other work on the current thread.
return;
}
//**************************************************
// Provides an event handler for the PeekCompleted
// event.
//**************************************************
private static void MyPeekCompleted(Object source,
PeekCompletedEventArgs asyncResult)
{
// Connect to the queue.
MessageQueue mq = (MessageQueue)source;
// End the asynchronous peek operation.
Message m = mq.EndPeek(asyncResult.AsyncResult);
// Display message information on the screen.
Console.WriteLine("Message: " + (string)m.Body);
// Restart the asynchronous peek operation.
mq.BeginPeek();
return;
}
}
}
Imports System.Messaging
' Provides a container class for the example.
Public Class MyNewQueue
' Provides an entry point into the application.
'
' This example performs asynchronous peek operation
' processing.
Public Shared Sub Main()
' Create an instance of MessageQueue. Set its formatter.
Dim myQueue As New MessageQueue(".\myQueue")
myQueue.Formatter = New XmlMessageFormatter(New Type() _
{GetType([String])})
' Add an event handler for the PeekCompleted event.
AddHandler myQueue.PeekCompleted, AddressOf _
MyPeekCompleted
' Begin the asynchronous peek operation.
myQueue.BeginPeek()
' Do other work on the current thread.
Return
End Sub
'**************************************************
' Provides an event handler for the PeekCompleted
' event.
'**************************************************
Private Shared Sub MyPeekCompleted(ByVal [source] As _
[Object], ByVal asyncResult As PeekCompletedEventArgs)
' Connect to the queue.
Dim mq As MessageQueue = CType([source], MessageQueue)
' End the asynchronous peek operation.
Dim m As Message = mq.EndPeek(asyncResult.AsyncResult)
' Display message information on the screen.
Console.WriteLine(("Message: " + CStr(m.Body)))
' Restart the asynchronous peek operation.
mq.BeginPeek()
Return
End Sub
End Class
Comentários
BeginPeek é usado no processamento assíncrono para gerar o PeekCompleted evento quando uma mensagem está disponível na fila.
EndPeek(IAsyncResult) é usado para concluir a operação iniciada por uma chamada para BeginPeek e espiar a mensagem quando o PeekCompleted evento é acionado.
Ao criar um PeekCompletedEventHandler delegado, você identifica o método que manipulará o evento. Para associar o evento ao manipulador de eventos, adicione uma instância do delegado ao evento. O manipulador de eventos é chamado sempre que o evento ocorre, a menos que você remova o representante. Para obter mais informações sobre delegados do manipulador de eventos, consulte Manipulando e levantando eventos.
