MessageQueue.GetMessageEnumerator 方法

定义

命名空间:

System.Messaging

程序集:

System.Messaging.dll

注意

This method returns a MessageEnumerator that implements RemoveCurrent family of methods incorrectly. Please use GetMessageEnumerator2 instead.

为队列中的所有消息创建枚举数对象。 GetMessageEnumerator() 已弃用。 应改用 GetMessageEnumerator2()。

public:
 System::Messaging::MessageEnumerator ^ GetMessageEnumerator();

[System.Obsolete("This method returns a MessageEnumerator that implements RemoveCurrent family of methods incorrectly. Please use GetMessageEnumerator2 instead.")]
public System.Messaging.MessageEnumerator GetMessageEnumerator ();

[<System.Obsolete("This method returns a MessageEnumerator that implements RemoveCurrent family of methods incorrectly. Please use GetMessageEnumerator2 instead.")>]
member this.GetMessageEnumerator : unit -> System.Messaging.MessageEnumerator

Public Function GetMessageEnumerator () As MessageEnumerator

返回

MessageEnumerator

该 MessageEnumerator 包括队列中所包含的消息。

属性

ObsoleteAttribute

示例

下面的代码示例获取队列中消息的动态列表，并将 属性设置为 MessagePriority.Lowest的所有消息Priority进行计数。

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

using namespace System;
using namespace System::Messaging;
ref class MyNewQueue
{
public:
   void CountLowestPriority()
   {
      
      // Holds the count of Lowest priority messages.
      UInt32 numberItems = 0;
      
      // Connect to a queue.
      MessageQueue^ myQueue = gcnew MessageQueue( ".\\myQueue" );
      
      // Get a cursor into the messages in the queue.
      MessageEnumerator^ myEnumerator = myQueue->GetMessageEnumerator();
      
      // Specify that the messages's priority should be read.
      myQueue->MessageReadPropertyFilter->Priority = true;
      
      // Move to the next message and examine its priority.
      while ( myEnumerator->MoveNext() )
      {
         
         // Increase the count if priority is Lowest.
         if ( myEnumerator->Current->Priority == MessagePriority::Lowest )
                  numberItems++;
      }

      
      // Display final count.
      Console::WriteLine( "Lowest priority messages: {0}", numberItems );
      return;
   }

};

int main()
{
   
   // Create a new instance of the class.
   MyNewQueue^ myNewQueue = gcnew MyNewQueue;
   
   // Output the count of Lowest priority messages.
   myNewQueue->CountLowestPriority();
   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 uses a cursor to step through the
        // messages in a queue and counts the number of
        // Lowest priority messages.
        //**************************************************

        public static void Main()
        {
            // Create a new instance of the class.
            MyNewQueue myNewQueue = new MyNewQueue();

            // Output the count of Lowest priority messages.
            myNewQueue.CountLowestPriority();
                        
            return;
        }

        //**************************************************
        // Iterates through messages in a queue and examines
        // their priority.
        //**************************************************
        
        public void CountLowestPriority()
        {
            // Holds the count of Lowest priority messages.
            uint numberItems = 0;

            // Connect to a queue.
            MessageQueue myQueue = new MessageQueue(".\\myQueue");
    
            // Get a cursor into the messages in the queue.
            MessageEnumerator myEnumerator =
                myQueue.GetMessageEnumerator();

            // Specify that the messages's priority should be read.
            myQueue.MessageReadPropertyFilter.Priority = true;

            // Move to the next message and examine its priority.
            while(myEnumerator.MoveNext())
            {
                // Increase the count if priority is Lowest.
                if(myEnumerator.Current.Priority ==
                    MessagePriority.Lowest)
                    
                    numberItems++;
            }

            // Display final count.
            Console.WriteLine("Lowest priority messages: " +
                numberItems.ToString());
            
            return;
        }
    }
}

Imports System.Messaging

Public Class MyNewQueue


        
        ' Provides an entry point into the application.
        '		 
        ' This example uses a cursor to step through the
        ' messages in a queue and counts the number of 
        ' Lowest priority messages.
        

        Public Shared Sub Main()

            ' Create a new instance of the class.
            Dim myNewQueue As New MyNewQueue()

            ' Output the count of Lowest priority messages.
            myNewQueue.CountLowestPriority()

            Return

        End Sub


        
        ' Iterates through messages in a queue and examines
        ' their priority.
        

        Public Sub CountLowestPriority()

            ' Holds the count of Lowest priority messages.
            Dim numberItems As Int32 = 0

            ' Connect to a queue.
            Dim myQueue As New MessageQueue(".\myQueue")

            ' Get a cursor into the messages in the queue.
            Dim myEnumerator As MessageEnumerator = _
                myQueue.GetMessageEnumerator()

            ' Specify that the messages's priority should be read.
            myQueue.MessageReadPropertyFilter.Priority = True

            ' Move to the next message and examine its priority.
            While myEnumerator.MoveNext()

                ' Increase the count if the priority is Lowest.
                If myEnumerator.Current.Priority = _
                    MessagePriority.Lowest Then
                    numberItems += 1
                End If

            End While

            ' Display final count.
            Console.WriteLine(("Lowest priority messages: " + _
                numberItems.ToString()))

            Return

        End Sub

End Class

注解

GetMessageEnumerator 创建队列中所有消息的动态列表。 可以通过调用 RemoveCurrentMessageEnumeratorGetMessageEnumerator 返回的 从队列中删除枚举器当前位置的消息。

由于游标与队列中消息的动态列表相关联，因此如果消息超出当前游标位置，则枚举将反映对队列中消息所做的任何修改。 例如，枚举器可以自动访问放置在光标当前位置之外的低优先级消息，但不能访问在该位置之前插入的较高优先级消息。 但是，可以通过调用 ResetMessageEnumerator来重置枚举，从而将光标移回列表的开头。

枚举中消息的顺序反映了它们在队列中的顺序，因此优先级较高的消息将出现在优先级较低的消息之前。

如果需要队列中消息的静态快照而不是动态连接，请调用 GetAllMessages。 此方法返回对象数组 Message ，这些对象表示调用方法时的消息。

下表显示了此方法是否在各种工作组模式下可用。

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	是
远程计算机和直接格式名称	是

另请参阅

• GetAllMessages()
• GetMessageEnumerator2()
• GetMessageQueueEnumerator()