MessageQueue.EndPeek(IAsyncResult) 方法

定義

命名空間:

System.Messaging

組件:

System.Messaging.dll

完成指定的非同步窺視作業。

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

asyncResult

IAsyncResult

IAsyncResult，識別要完成的非同步窺視作業，並要從其中擷取最終結果。

傳回

Message

與完成的非同步作業相關的 Message。

例外狀況

ArgumentNullException

asyncResult 參數為 null。

ArgumentException

asyncResult 參數的語法無效。

MessageQueueException

存取訊息佇列方法時發生錯誤。

範例

下列程式代碼範例會建立名為 MyPeekCompleted的事件處理程式，並將它附加至 PeekCompleted 事件處理程式委派，並呼叫 BeginPeek 以在位於 “.\myQueue” 路徑的佇列上起始異步查看作業。 PeekCompleted引發事件時，範例會查看訊息，並將其本文寫入畫面。 然後，此範例會再次呼叫 BeginPeek ，以起始新的異步查看作業。

#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

PeekCompleted引發事件時，EndPeek(IAsyncResult)完成呼叫所起始的BeginPeek作業。 若要這樣做， EndPeek(IAsyncResult) 請查看訊息。

BeginPeek 可以指定逾時，這會導致 PeekCompleted 在訊息出現在佇列中的訊息之前引發事件。 當逾時發生時，沒有訊息抵達佇列時，後續呼叫 會 EndPeek(IAsyncResult) 擲回例外狀況。

EndPeek(IAsyncResult) 用來讀取導致 PeekCompleted 引發事件的訊息。

如果您要繼續以異步方式查看訊息，您可以在呼叫 之後再次呼叫 BeginPeekEndPeek(IAsyncResult)。

下表顯示這個方法是否可在各種工作組模式中使用。

工作組模式	可用
本機電腦	是
本機計算機和直接格式名稱	是
遠端電腦	否
遠端電腦和直接格式名稱	是

另請參閱

• BeginPeek()
• PeekCompleted