MessageQueue.EndReceive(IAsyncResult) 方法

定义

命名空间:

System.Messaging

程序集:

System.Messaging.dll

完成指定的异步接收操作。

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

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

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

Public Function EndReceive (asyncResult As IAsyncResult) As Message

参数

asyncResult

IAsyncResult

该 IAsyncResult 标识要完成的异步接收操作，并且从它检索最终结果。

返回

Message

该 Message 与已完成的异步操作关联。

例外

ArgumentNullException

asyncResult 参数为 null。

ArgumentException

该 asyncResult 参数的语法无效。

MessageQueueException

访问“消息队列”方法时出错。

示例

下面的代码示例链接异步请求。 它假定本地计算机上有一个名为“myQueue”的队列。 函数 Main 开始由 MyReceiveCompleted 例程处理的异步操作。 MyReceiveCompleted 处理当前消息并开始新的异步接收操作。

#using <system.dll>
#using <system.messaging.dll>

using namespace System;
using namespace System::Messaging;
using namespace System::Threading;

ref class MyNewQueue
{
public:

   // Define static class members.
   static ManualResetEvent^ signal = gcnew ManualResetEvent( false );
   static int count = 0;

   // Provides an event handler for the ReceiveCompleted
   // event.
   static void MyReceiveCompleted( Object^ source, ReceiveCompletedEventArgs^ asyncResult )
   {
      try
      {
         // Connect to the queue.
         MessageQueue^ mq = dynamic_cast<MessageQueue^>(source);

         // End the asynchronous receive operation.
         mq->EndReceive( asyncResult->AsyncResult );
         count += 1;
         if ( count == 10 )
         {
            signal->Set();
         }

         // Restart the asynchronous receive operation.
         mq->BeginReceive();
      }
      catch ( MessageQueueException^ ) 
      {
         // Handle sources of MessageQueueException.
      }

      // Handle other exceptions.
      return;
   }
};

// Provides an entry point into the application.
//         
// This example performs asynchronous receive
// operation processing.
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 ReceiveCompleted event.
   myQueue->ReceiveCompleted += gcnew ReceiveCompletedEventHandler( MyNewQueue::MyReceiveCompleted );

   // Begin the asynchronous receive operation.
   myQueue->BeginReceive();
   MyNewQueue::signal->WaitOne();

   // Do other work on the current thread.
   return 0;
}

using System;
using System.Messaging;
using System.Threading;

namespace MyProject
{
    /// <summary>
    /// Provides a container class for the example.
    /// </summary>
    public class MyNewQueue
    {
        // Define static class members.
        static ManualResetEvent signal = new ManualResetEvent(false);
        static int count = 0;

        //**************************************************
        // Provides an entry point into the application.
        //		
        // This example performs asynchronous receive
        // 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 ReceiveCompleted event.
            myQueue.ReceiveCompleted +=
                new ReceiveCompletedEventHandler(MyReceiveCompleted);
            
            // Begin the asynchronous receive operation.
            myQueue.BeginReceive();

            signal.WaitOne();
            
            // Do other work on the current thread.

            return;
        }

        //***************************************************
        // Provides an event handler for the ReceiveCompleted
        // event.
        //***************************************************
        
        private static void MyReceiveCompleted(Object source,
            ReceiveCompletedEventArgs asyncResult)
        {
            try
            {
                // Connect to the queue.
                MessageQueue mq = (MessageQueue)source;

                // End the asynchronous receive operation.
                Message m = mq.EndReceive(asyncResult.AsyncResult);
                
                count += 1;
                if (count == 10)
                {
                    signal.Set();
                }

                // Restart the asynchronous receive operation.
                mq.BeginReceive();
            }
            catch(MessageQueueException)
            {
                // Handle sources of MessageQueueException.
            }
            
            // Handle other exceptions.
            
            return;
        }
    }
}

Imports System.Messaging
Imports System.Threading




' Provides a container class for the example.

Public Class MyNewQueue

        ' Define static class members.
        Private Shared signal As New ManualResetEvent(False)
        Private Shared count As Integer = 0



        ' Provides an entry point into the application.
        '		 
        ' This example performs asynchronous receive
        ' 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 ReceiveCompleted event.
            AddHandler myQueue.ReceiveCompleted, AddressOf _
                MyReceiveCompleted

            ' Begin the asynchronous receive operation.
            myQueue.BeginReceive()

            signal.WaitOne()

            ' Do other work on the current thread.

            Return

        End Sub



        ' Provides an event handler for the ReceiveCompleted
        ' event.


        Private Shared Sub MyReceiveCompleted(ByVal [source] As _
            [Object], ByVal asyncResult As ReceiveCompletedEventArgs)

            Try
                ' Connect to the queue.
                Dim mq As MessageQueue = CType([source], MessageQueue)

                ' End the asynchronous receive operation.
                Dim m As Message = _
                    mq.EndReceive(asyncResult.AsyncResult)

                count += 1
                If count = 10 Then
                    signal.Set()
                End If

                ' Restart the asynchronous receive operation.
                mq.BeginReceive()

            Catch
                ' Handle sources of MessageQueueException.

                ' Handle other exceptions.

            End Try

            Return

        End Sub

End Class

注解

ReceiveCompleted引发 事件时，EndReceive(IAsyncResult)完成调用BeginReceive启动的操作。 为此， EndReceive(IAsyncResult) 接收消息。

BeginReceive 可以指定超时，如果超时发生在消息出现在队列中之前，则会导致 ReceiveCompleted 引发事件。 如果发生超时，但消息到达队列时，对 的后续调用 EndReceive(IAsyncResult) 将引发异常。

EndReceive(IAsyncResult) 用于读取 (从队列中删除) 导致 ReceiveCompleted 引发事件的消息。

如果要继续异步接收消息，可以在调用 后再次调用 BeginReceiveEndReceive(IAsyncResult)。

下表显示了此方法在各种工作组模式下是否可用。

工作组模式	可用
本地计算机	是
本地计算机和直接格式名称	是
远程计算机	否
远程计算机和直接格式名称	是

另请参阅

• BeginReceive()
• ReceiveCompleted