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Observable.FromEventPattern < TEventArgs > 方法 (物件，String)

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使用反映來尋找實例事件，將符合標準 .NET 事件模式的 .NET 事件轉換為可觀察的序列。

Namespace：System.Reactive.Linq
裝配： System.Reactive.dll) 中的 System.Reactive (

Syntax

'Declaration
Public Shared Function FromEventPattern(Of TEventArgs As EventArgs) ( _
    target As Object, _
    eventName As String _
) As IObservable(Of EventPattern(Of TEventArgs))

'Usage
Dim target As Object
Dim eventName As String
Dim returnValue As IObservable(Of EventPattern(Of TEventArgs))

returnValue = Observable.FromEventPattern(target, _
    eventName)

public static IObservable<EventPattern<TEventArgs>> FromEventPattern<TEventArgs>(
    Object target,
    string eventName
)
where TEventArgs : EventArgs

public:
generic<typename TEventArgs>
where TEventArgs : EventArgs
static IObservable<EventPattern<TEventArgs>^>^ FromEventPattern(
    Object^ target, 
    String^ eventName
)

static member FromEventPattern : 
        target:Object * 
        eventName:string -> IObservable<EventPattern<'TEventArgs>>  when 'TEventArgs : EventArgs

JScript does not support generic types and methods.

類型參數

  • TEventArgs
    事件的類型。

參數

  • 目標
    類型： System.Object
    公開要轉換之事件的物件實例。

傳回值

類型：System.IObservable<EventPattern< TEventArgs>>
傳回值是可觀察的序列，其中包含基礎 .NET 事件調用的資料表示。

備註

FromEventPattern 運算子會將 .Net 事件轉換成EventPattern < TEventArgs >序列。 每個 EventPattern 實例都包含事件引數和傳送事件的物件。 事件引數是在序列中傳遞之每個 EventPattern 的 EventArgs 屬性中提供。 傳送事件的物件是在 EventPattern 實例的 Sender 屬性中提供。 所要的事件是藉由傳遞物件，將事件公開為 目標 參數，以及將 eventName 參數設定為事件的名稱來指定。 TEventArgs類型會指定每個事件將傳遞的事件引數類型。

範例

此範例程式碼示範如何使用 FromEventPattern 運算子接聽 System.IO.FileSystemWatcher 上的建立、重新命名和刪除事件。 此範例會監看 C：\Users\Public 資料夾中的變更，並將事件寫入主控台視窗。

using System;
using System.Reactive.Linq;
using System.Reactive;
using System.IO;

namespace Example
{
  class Program
  {
    static void Main()
    {
      //*********************************************************************************************************************//
      //*** Create a FileSystemWatcher to watch the C:\Users\Public directory using the default NotifyFilter watching for ***//
      //*** changes to any type of file.                                                                                  ***//
      //*********************************************************************************************************************//

      FileSystemWatcher fsw = new FileSystemWatcher(@"C:\Users\Public", "*.*");
      fsw.EnableRaisingEvents = true;


      //***************************************************************************************//
      //*** Use the FromEventPattern operator to setup a subscription to the Created event. ***//
      //***************************************************************************************//

      IObservable<EventPattern<FileSystemEventArgs>> fswCreated = Observable.FromEventPattern<FileSystemEventArgs>(fsw, "Created");
      fswCreated.Subscribe(pattern => Console.WriteLine("{0} was created in {1}.", pattern.EventArgs.Name, ((FileSystemWatcher)pattern.Sender).Path));


      //***************************************************************************************//
      //*** Use the FromEventPattern operator to setup a subscription to the Renamed event. ***//
      //***************************************************************************************//

      IObservable<EventPattern<RenamedEventArgs>> fswRenamed = Observable.FromEventPattern<RenamedEventArgs>(fsw, "Renamed");
      fswRenamed.Subscribe(pattern => Console.WriteLine("{0} was renamed to {1} in {2}.", pattern.EventArgs.OldName, 
                                                        pattern.EventArgs.Name, ((FileSystemWatcher)pattern.Sender).Path));


      //***************************************************************************************//
      //*** Use the FromEventPattern operator to setup a subscription to the Deleted event. ***//
      //***************************************************************************************//

      IObservable<EventPattern<FileSystemEventArgs>> fswDeleted = Observable.FromEventPattern<FileSystemEventArgs>(fsw, "Deleted");
      fswDeleted.Subscribe(pattern => Console.WriteLine("{0} was deleted in {1}.", pattern.EventArgs.Name, ((FileSystemWatcher)pattern.Sender).Path));


      Console.WriteLine("Press ENTER to exit...\n");
      Console.ReadLine();
    }
  }
}

下列輸出示範如何執行範例程式碼，以在 C：\Users\Public 目錄中建立新的文字檔。 檔案已重新命名為ExFile.txt，然後刪除。

Press ENTER to exit...

New Text Document.txt was created in C:\Users\Public.
New Text Document.txt was renamed to ExFile.txt in C:\Users\Public.
ExFile.txt was deleted in C:\Users\Public.

另請參閱

參考

Observable 類別

FromEventPattern 多載

System.Reactive.Linq 命名空間