MessageQueue.EndPeek(IAsyncResult) 方法

public:
 System::Messaging::Message ^ EndPeek(IAsyncResult ^ asyncResult);

public System.Messaging.Message EndPeek(IAsyncResult asyncResult);

member this.EndPeek : IAsyncResult -> System.Messaging.Message

Public Function EndPeek (asyncResult As IAsyncResult) As Message

參數

傳回

Message與完成的非同步操作有關。

例外狀況

範例

以下程式碼範例建立一個名為 MyPeekCompleted的事件處理器，並將其附加到 PeekCompleted 事件處理器代理器，並呼叫 BeginPeek 對位於路徑「.\myQueue」的隊列發起非同步窺視操作。 當 PeekCompleted 事件被提出時，範例會探出訊息並寫入主體到螢幕。 範例接著再次呼叫 BeginPeek 以啟動新的非同步窺視操作。

#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

備註

當 PeekCompleted 事件被提出時，完成 EndPeek(IAsyncResult) 了由 BeginPeek 呼叫所發起的操作。 要做到這點，就 EndPeek(IAsyncResult) 要偷看訊息。

BeginPeek 可以指定一個逾時，若逾時發生在訊息出現於隊列前，事件會被 PeekCompleted 觸發。 當逾時發生且隊列中沒有訊息時，後續呼叫 EndPeek(IAsyncResult) 會拋出例外。

EndPeek(IAsyncResult) 用來讀取導致 PeekCompleted 事件被觸發的訊息。

如果你想繼續非同步偷看訊息，可以一 BeginPeek 打又一 EndPeek(IAsyncResult)打。

下表顯示此方法是否可在多種工作群組模式中使用。

另請參閱

• BeginPeek()
• PeekCompleted