MessageQueue.GetMessageEnumerator 方法
定义
注意
This method returns a MessageEnumerator that implements RemoveCurrent family of methods incorrectly. Please use GetMessageEnumerator2 instead.
注意
此 API 现已过时。
为队列中的所有消息创建枚举数对象。Creates an enumerator object for all the messages in the queue. GetMessageEnumerator() 已弃用。GetMessageEnumerator() is deprecated. 应改用 GetMessageEnumerator2()。GetMessageEnumerator2() should be used instead.
public:
System::Messaging::MessageEnumerator ^ GetMessageEnumerator();
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]
public System.Messaging.MessageEnumerator GetMessageEnumerator ();
member this.GetMessageEnumerator : unit -> System.Messaging.MessageEnumerator
[<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
[<System.Obsolete>]
member this.GetMessageEnumerator : unit -> System.Messaging.MessageEnumerator
Public Function GetMessageEnumerator () As MessageEnumerator
返回
该 MessageEnumerator 包括队列中所包含的消息。The MessageEnumerator holding the messages that are contained in the queue.
- 属性
示例
下面的代码示例获取队列中消息的动态列表,并对属性设置为的所有消息进行计数 Priority MessagePriority.Lowest 。The following code example gets a dynamic list of messages in a queue and counts all messages with the Priority property set to MessagePriority.Lowest.
#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。GetMessageEnumerator creates a dynamic list of all the messages in a queue. 你可以通过调用返回的来从队列中删除消息,该消息位于枚举数的当前位置 RemoveCurrent MessageEnumerator GetMessageEnumerator 。You can remove from the queue the message at the enumerator's current position by calling RemoveCurrent for the MessageEnumerator that GetMessageEnumerator returns.
由于游标与队列中的消息动态列表相关联,因此,如果消息在当前游标位置之外,则枚举将反映对队列中的消息所做的任何修改。Because the cursor is associated with the dynamic list of messages in the queue, the enumeration reflects any modification you make to the messages in the queue, if the message is beyond the current cursor position. 例如,枚举器可以自动访问放置在游标当前位置之外的低优先级的消息,但不能访问在该位置之前插入的优先级较高的消息。For example, the enumerator can automatically access a lower-priority message placed beyond the cursor's current position, but not a higher-priority message inserted before that position. 但是,你可以通过调用来重置枚举,从而将游标移回列表的开头 Reset MessageEnumerator 。However, you can reset the enumeration, thereby moving the cursor back to the beginning of the list, by calling Reset for the MessageEnumerator.
枚举中的消息顺序反映了它们在队列中的顺序,因此优先级较高的消息会出现在优先级较低的消息之前。The order of the messages in the enumeration reflects their order in the queue, so higher-priority messages will appear before lower-priority ones.
如果希望队列中消息的静态快照而不是动态连接到它们,请调用 GetAllMessages 。If you want a static snapshot of the messages in the queue rather than a dynamic connection to them, call GetAllMessages. 此方法返回对象的数组 Message ,这些对象表示调用方法时的消息。This method returns an array of Message objects, which represent the messages at the time the method was called.
下表显示了此方法是否在各种工作组模式下可用。The following table shows whether this method is available in various Workgroup modes.
| 工作组模式Workgroup mode | 可用Available |
|---|---|
| 本地计算机Local computer | 是Yes |
| 本地计算机和直接格式名称Local computer and direct format name | 是Yes |
| 远程计算机Remote computer | 是Yes |
| 远程计算机和直接格式名称Remote computer and direct format name | 是Yes |