共用方式為

Observable.FromAsyncPattern < T1， TResult > 方法 (Func < T1， AsyncCallback， Object， IAsyncResult > ， Func < IAsyncResult， TResult >)

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將 Begin/End invoke 函式組轉換成非同步函式。

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

Syntax

'Declaration
Public Shared Function FromAsyncPattern(Of T1, TResult) ( _
    begin As Func(Of T1, AsyncCallback, Object, IAsyncResult), _
    end As Func(Of IAsyncResult, TResult) _
) As Func(Of T1, IObservable(Of TResult))

'Usage
Dim begin As Func(Of T1, AsyncCallback, Object, IAsyncResult)
Dim end As Func(Of IAsyncResult, TResult)
Dim returnValue As Func(Of T1, IObservable(Of TResult))

returnValue = Observable.FromAsyncPattern(begin, _
    end)

public static Func<T1, IObservable<TResult>> FromAsyncPattern<T1, TResult>(
    Func<T1, AsyncCallback, Object, IAsyncResult> begin,
    Func<IAsyncResult, TResult> end
)

public:
generic<typename T1, typename TResult>
static Func<T1, IObservable<TResult>^>^ FromAsyncPattern(
    Func<T1, AsyncCallback^, Object^, IAsyncResult^>^ begin, 
    Func<IAsyncResult^, TResult>^ end
)

static member FromAsyncPattern : 
        begin:Func<'T1, AsyncCallback, Object, IAsyncResult> * 
        end:Func<IAsyncResult, 'TResult> -> Func<'T1, IObservable<'TResult>> 

JScript does not support generic types and methods.

類型參數

  • T1
    函式的第一種類型。
  • TResult
    結果的類型。

參數

傳回值

類型：System.Func< T1、IObservable< TResult>>
Begin/End invoke 函式配對。

備註

FromAsyncPattern 運算子可用來簡化進行非同步呼叫。 它會使用非同步函式包裝非同步呼叫，以開始/結束叫用，以為您處理非同步呼叫。 函式會傳回與結果相同類型的可觀察序列。 例如，您可以設定 System.IO.Directory.GetFiles 的非同步呼叫。 該方法的結果是包含所要求檔案清單的字串陣列。 因此，從 FromAsyncPattern 運算子傳回的非同步函式會傳回可觀察的字串序列[]。 本主題的範例程式碼會示範這一點。 此運算子有各種多載，可處理採用不同數目輸入參數的方法呼叫。 若要設定非同步呼叫，請使用 FromAsyncPattern 運算子的呼叫來指定型別。 指定的最終型別是傳回實值型別。 例如，System.IO.Directory.GetFiles 最多可能需要三個輸入參數，並傳回字串陣列作為結果。 下列程式碼片段顯示類型的順序。

delegate string[] GetFilesDelegate(string searchPath, string searchPattern, SearchOption searchOption);


GetFilesDelegate getFiles = Directory.GetFiles;


//**************************************************************************************************//
//***  Observable.FromAsyncPattern<Param 1 Type, Param 2 Type, Param 3 Type, Return value type>  ***//
//**************************************************************************************************//
var getFileList = Observable.FromAsyncPattern<string, string, SearchOption, string[]>(getFiles.BeginInvoke, getFiles.EndInvoke);

範例

此範例示範以非同步方式呼叫 System.IO.Direcotry.GetFile，以列舉 C：\Program Files 目錄下的所有檔案。 此範例使用 FromAsyncPattern 運算子所提供的非同步函式。 動作事件處理常式可作為非同步呼叫的回呼，以將結果中的每個檔案名寫入主控台視窗。

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

namespace Example
{                                       
  delegate string[] GetFilesDelegate(string searchPath, string searchPattern, SearchOption searchOption);

  class Program
  {
    static void Main()
    {                                                                                                                    
      //********************************************************************************************************************//
      //*** For this example, Reactive Extensions is used to wrap an asynchronous call that recursively enumerates files ***//
      //*** in a given directory.                                                                                        ***//
      //********************************************************************************************************************//
      string mySearchPath = "C:\\Program Files";                                                                                   
      GetFilesDelegate getFiles = Directory.GetFiles;


      //*****************************************************************************************************************************//
      //*** Reactive Extensions will wrap the asynchronous call to the delegate returning the asynchronous function, getFileList. ***//
      //*** Calling the asynchronous function returns the observable sequence of the string[].                                    ***//
      //***                                                                                                                       ***//
      //*** There are many overloaded versions of the FromAsyncPattern operator. The types signified here are based on parameters ***//
      //*** in the signature of actual method being called asynchronously. The types are specified in their proper order followed ***//
      //*** by the return type (ex. <Param 1 type, Param 2 type, Param 3 type, return type> ).                                    ***//
      //*****************************************************************************************************************************//
      var getFileList = Observable.FromAsyncPattern<string, string, SearchOption, string[]>(getFiles.BeginInvoke, getFiles.EndInvoke);    
      IObservable<string[]> fileObservable = getFileList(mySearchPath,"*.*",SearchOption.AllDirectories);


      //*********************************************************************************************************************//
      //*** We subscribe to this sequence with an action event handler defined with the lambda expression. It acts as the ***//
      //*** callback for completion of the asynchronous operation.                                                        ***//
      //*********************************************************************************************************************//
      fileObservable.Subscribe(fileList =>
      {
        foreach (string f in fileList)
        {
          Console.WriteLine(f.ToString());
        }
      });


      Console.WriteLine("Running async enumeration of the {0} directory.\n\nPress ENTER to cancel...\n",mySearchPath);
      Console.ReadLine();
    }
  }
}

下列範例輸出是由範例程式碼所產生。

Running async enumeration of the C:\Program Files directory.

Press ENTER to cancel...

C:\Program Files\desktop.ini
C:\Program Files\ATI\CIM\Bin64\atdcm64a.sys
C:\Program Files\ATI\CIM\Bin64\ATILog.dll
C:\Program Files\ATI\CIM\Bin64\ATIManifestDLMExt.dll
C:\Program Files\ATI\CIM\Bin64\ATISetup.exe
C:\Program Files\ATI\CIM\Bin64\CompressionDLMExt.dll
C:\Program Files\ATI\CIM\Bin64\CRCVerDLMExt.dll
C:\Program Files\ATI\CIM\Bin64\DetectionManager.dll
C:\Program Files\ATI\CIM\Bin64\difxapi.dll
C:\Program Files\ATI\CIM\Bin64\DLMCom.dll
C:\Program Files\ATI\CIM\Bin64\EncryptionDLMExt.dll
C:\Program Files\ATI\CIM\Bin64\InstallManager.dll
C:\Program Files\ATI\CIM\Bin64\InstallManagerApp.exe
C:\Program Files\ATI\CIM\Bin64\InstallManagerApp.exe.manifest
C:\Program Files\ATI\CIM\Bin64\LanguageMgr.dll
C:\Program Files\ATI\CIM\Bin64\mfc80u.dll
C:\Program Files\ATI\CIM\Bin64\Microsoft.VC80.ATL.manifest
C:\Program Files\ATI\CIM\Bin64\Microsoft.VC80.CRT.manifest
C:\Program Files\ATI\CIM\Bin64\Microsoft.VC80.MFC.manifest
C:\Program Files\ATI\CIM\Bin64\Microsoft.VC80.MFCLOC.manifest
C:\Program Files\ATI\CIM\Bin64\Microsoft.VC80.OpenMP.manifest
C:\Program Files\ATI\CIM\Bin64\msvcp80.dll
C:\Program Files\ATI\CIM\Bin64\msvcr80.dll
C:\Program Files\ATI\CIM\Bin64\PackageManager.dll
C:\Program Files\ATI\CIM\Bin64\readme.rtf
C:\Program Files\ATI\CIM\Bin64\SetACL64.exe

另請參閱

參考

Observable 類別

FromAsyncPattern 多載

System.Reactive.Linq 命名空間