Process.BeginOutputReadLine Metoda

Definicja

Rozpoczyna asynchroniczne operacje odczytu w przekierowanym StandardOutput strumieniu aplikacji.Begins asynchronous read operations on the redirected StandardOutput stream of the application.

public:
 void BeginOutputReadLine();
public void BeginOutputReadLine ();
[System.Runtime.InteropServices.ComVisible(false)]
public void BeginOutputReadLine ();
member this.BeginOutputReadLine : unit -> unit
[<System.Runtime.InteropServices.ComVisible(false)>]
member this.BeginOutputReadLine : unit -> unit
Public Sub BeginOutputReadLine ()
Atrybuty

Wyjątki

RedirectStandardOutputWłaściwość jest false .The RedirectStandardOutput property is false.

-lub--or- Asynchroniczna operacja odczytu jest już w toku w StandardOutput strumieniu.An asynchronous read operation is already in progress on the StandardOutput stream.

-lub--or- StandardOutputStrumień został użyty w operacji odczytu synchronicznego.The StandardOutput stream has been used by a synchronous read operation.

Przykłady

Poniższy przykład ilustruje sposób wykonywania asynchronicznych operacji odczytu w przekierowanym StandardOutput strumieniu sort polecenia.The following example illustrates how to perform asynchronous read operations on the redirected StandardOutput stream of the sort command. sortPolecenie jest aplikacją konsolową, która odczytuje i sortuje dane wejściowe tekstu.The sort command is a console application that reads and sorts text input.

Przykład tworzy delegata zdarzenia dla SortOutputHandler programu obsługi zdarzeń i kojarzy go ze OutputDataReceived zdarzeniem.The example creates an event delegate for the SortOutputHandler event handler and associates it with the OutputDataReceived event. Program obsługi zdarzeń odbiera wiersze tekstowe z przekierowanego StandardOutput strumienia, formatuje tekst i zapisuje tekst na ekranie.The event handler receives text lines from the redirected StandardOutput stream, formats the text, and writes the text to the screen.

// Define the namespaces used by this sample.
#using <System.dll>

using namespace System;
using namespace System::Text;
using namespace System::IO;
using namespace System::Diagnostics;
using namespace System::Threading;
using namespace System::ComponentModel;

ref class SortOutputRedirection
{
private:
   // Define static variables shared by class methods.
   static StringBuilder^ sortOutput = nullptr;
   static int numOutputLines = 0;

public:
   static void SortInputListText()
   {
      // Initialize the process and its StartInfo properties.
      // The sort command is a console application that
      // reads and sorts text input.

      Process^ sortProcess;
      sortProcess = gcnew Process;
      sortProcess->StartInfo->FileName = "Sort.exe";
      
      // Set UseShellExecute to false for redirection.
      sortProcess->StartInfo->UseShellExecute = false;
      
      // Redirect the standard output of the sort command.  
      // This stream is read asynchronously using an event handler.
      sortProcess->StartInfo->RedirectStandardOutput = true;
      sortOutput = gcnew StringBuilder;
      
      // Set our event handler to asynchronously read the sort output.
      sortProcess->OutputDataReceived += gcnew DataReceivedEventHandler( SortOutputHandler );
      
      // Redirect standard input as well.  This stream
      // is used synchronously.
      sortProcess->StartInfo->RedirectStandardInput = true;
      
      // Start the process.
      sortProcess->Start();
      
      // Use a stream writer to synchronously write the sort input.
      StreamWriter^ sortStreamWriter = sortProcess->StandardInput;
      
      // Start the asynchronous read of the sort output stream.
      sortProcess->BeginOutputReadLine();
      
      // Prompt the user for input text lines.  Write each 
      // line to the redirected input stream of the sort command.
      Console::WriteLine( "Ready to sort up to 50 lines of text" );

      String^ inputText;
      int numInputLines = 0;
      do
      {
         Console::WriteLine( "Enter a text line (or press the Enter key to stop):" );

         inputText = Console::ReadLine();
         if (  !String::IsNullOrEmpty( inputText ) )
         {
            numInputLines++;
            sortStreamWriter->WriteLine( inputText );
         }
      }
      while (  !String::IsNullOrEmpty( inputText ) && (numInputLines < 50) );

      Console::WriteLine( "<end of input stream>" );
      Console::WriteLine();
      
      // End the input stream to the sort command.
      sortStreamWriter->Close();
      
      // Wait for the sort process to write the sorted text lines.
      sortProcess->WaitForExit();

      if ( numOutputLines > 0 )
      {
         
         // Write the formatted and sorted output to the console.
         Console::WriteLine( " Sort results = {0} sorted text line(s) ",
            numOutputLines.ToString() );
         Console::WriteLine( "----------" );
         Console::WriteLine( sortOutput->ToString() );
      }
      else
      {
         Console::WriteLine( " No input lines were sorted." );
      }

      sortProcess->Close();
   }

private:
   static void SortOutputHandler( Object^ /*sendingProcess*/,
      DataReceivedEventArgs^ outLine )
   {
      // Collect the sort command output.
      if (  !String::IsNullOrEmpty( outLine->Data ) )
      {
         numOutputLines++;
         
         // Add the text to the collected output.
         sortOutput->AppendFormat( "\n[{0}] {1}",
            numOutputLines.ToString(), outLine->Data );
      }
   }
};

/// The main entry point for the application.
void main()
{
   try
   {
      SortOutputRedirection::SortInputListText();
   }
   catch ( InvalidOperationException^ e ) 
   {
      Console::WriteLine( "Exception:" );
      Console::WriteLine( e );
   }
}
// Define the namespaces used by this sample.
using System;
using System.Text;
using System.IO;
using System.Diagnostics;
using System.Threading;
using System.ComponentModel;

namespace ProcessAsyncStreamSamples
{
    class SortOutputRedirection
    {
        // Define static variables shared by class methods.
        private static StringBuilder sortOutput = null;
        private static int numOutputLines = 0;

        public static void SortInputListText()
        {
            // Initialize the process and its StartInfo properties.
            // The sort command is a console application that
            // reads and sorts text input.

            Process sortProcess = new Process();
            sortProcess.StartInfo.FileName = "Sort.exe";

            // Set UseShellExecute to false for redirection.
            sortProcess.StartInfo.UseShellExecute = false;

            // Redirect the standard output of the sort command.
            // This stream is read asynchronously using an event handler.
            sortProcess.StartInfo.RedirectStandardOutput = true;
            sortOutput = new StringBuilder();

            // Set our event handler to asynchronously read the sort output.
            sortProcess.OutputDataReceived += SortOutputHandler;

            // Redirect standard input as well.  This stream
            // is used synchronously.
            sortProcess.StartInfo.RedirectStandardInput = true;

            // Start the process.
            sortProcess.Start();

            // Use a stream writer to synchronously write the sort input.
            StreamWriter sortStreamWriter = sortProcess.StandardInput;

            // Start the asynchronous read of the sort output stream.
            sortProcess.BeginOutputReadLine();

            // Prompt the user for input text lines.  Write each
            // line to the redirected input stream of the sort command.
            Console.WriteLine("Ready to sort up to 50 lines of text");

            String inputText;
            int numInputLines = 0;
            do
            {
                Console.WriteLine("Enter a text line (or press the Enter key to stop):");

                inputText = Console.ReadLine();
                if (!String.IsNullOrEmpty(inputText))
                {
                    numInputLines++;
                    sortStreamWriter.WriteLine(inputText);
                }
            }
            while (!String.IsNullOrEmpty(inputText) && (numInputLines < 50));
            Console.WriteLine("<end of input stream>");
            Console.WriteLine();

            // End the input stream to the sort command.
            sortStreamWriter.Close();

            // Wait for the sort process to write the sorted text lines.
            sortProcess.WaitForExit();

            if (numOutputLines > 0)
            {
                // Write the formatted and sorted output to the console.
                Console.WriteLine($" Sort results = {numOutputLines} sorted text line(s) ");
                Console.WriteLine("----------");
                Console.WriteLine(sortOutput);
            }
            else
            {
                Console.WriteLine(" No input lines were sorted.");
            }

            sortProcess.Close();
        }

        private static void SortOutputHandler(object sendingProcess,
            DataReceivedEventArgs outLine)
        {
            // Collect the sort command output.
            if (!String.IsNullOrEmpty(outLine.Data))
            {
                numOutputLines++;

                // Add the text to the collected output.
                sortOutput.Append(Environment.NewLine +
                    $"[{numOutputLines}] - {outLine.Data}");
            }
        }
    }
}

namespace ProcessAsyncStreamSamples
{

    class ProcessSampleMain
    {
        /// The main entry point for the application.
        static void Main()
        {
            try
            {
                SortOutputRedirection.SortInputListText();
            }
            catch (InvalidOperationException e)
            {
                Console.WriteLine("Exception:");
                Console.WriteLine(e);
            }
        }
    }
}
' Define the namespaces used by this sample.
Imports System.Text
Imports System.IO
Imports System.Diagnostics
Imports System.Threading
Imports System.ComponentModel

Namespace ProcessAsyncStreamSamples

    Class ProcessAsyncOutputRedirection
        ' Define static variables shared by class methods.
        Private Shared sortOutput As StringBuilder = Nothing
        Private Shared numOutputLines As Integer = 0

        Public Shared Sub SortInputListText()

            ' Initialize the process and its StartInfo properties.
            ' The sort command is a console application that
            ' reads and sorts text input.
            Dim sortProcess As New Process()
            sortProcess.StartInfo.FileName = "Sort.exe"

            ' Set UseShellExecute to false for redirection.
            sortProcess.StartInfo.UseShellExecute = False

            ' Redirect the standard output of the sort command.  
            ' Read the stream asynchronously using an event handler.
            sortProcess.StartInfo.RedirectStandardOutput = True
            sortOutput = New StringBuilder()

            ' Set our event handler to asynchronously read the sort output.
            AddHandler sortProcess.OutputDataReceived, AddressOf SortOutputHandler

            ' Redirect standard input as well.  This stream
            ' is used synchronously.
            sortProcess.StartInfo.RedirectStandardInput = True

            ' Start the process.
            sortProcess.Start()

            ' Use a stream writer to synchronously write the sort input.
            Dim sortStreamWriter As StreamWriter = sortProcess.StandardInput

            ' Start the asynchronous read of the sort output stream.
            sortProcess.BeginOutputReadLine()

            ' Prompt the user for input text lines.  Write each 
            ' line to the redirected input stream of the sort command.
            Console.WriteLine("Ready to sort up to 50 lines of text")

            Dim inputText As String
            Dim numInputLines As Integer = 0
            Do
                Console.WriteLine("Enter a text line (or press the Enter key to stop):")

                inputText = Console.ReadLine()
                If Not String.IsNullOrEmpty(inputText) Then
                    numInputLines += 1
                    sortStreamWriter.WriteLine(inputText)
                End If
            Loop While Not String.IsNullOrEmpty(inputText) AndAlso numInputLines < 50
            Console.WriteLine("<end of input stream>")
            Console.WriteLine()

            ' End the input stream to the sort command.
            sortStreamWriter.Close()

            ' Wait for the sort process to write the sorted text lines.
            sortProcess.WaitForExit()

            If Not String.IsNullOrEmpty(numOutputLines) Then
                ' Write the formatted and sorted output to the console.
                Console.WriteLine($" Sort results = {numOutputLines} sorted text line(s) ")
                Console.WriteLine("----------")
                Console.WriteLine(sortOutput)
            Else
                Console.WriteLine(" No input lines were sorted.")
            End If

            sortProcess.Close()
        End Sub

        Private Shared Sub SortOutputHandler(sendingProcess As Object,
           outLine As DataReceivedEventArgs)

            ' Collect the sort command output.
            If Not String.IsNullOrEmpty(outLine.Data) Then
                numOutputLines += 1

                ' Add the text to the collected output.
                sortOutput.Append(Environment.NewLine +
                    $"[{numOutputLines}] - {outLine.Data}")
            End If
        End Sub
    End Class
End Namespace

Namespace ProcessAsyncStreamSamples

    Class ProcessSampleMain

        ' The main entry point for the application.
        Shared Sub Main()
            Try
                ProcessAsyncOutputRedirection.SortInputListText()

            Catch e As InvalidOperationException
                Console.WriteLine("Exception:")
                Console.WriteLine(e)
            End Try
        End Sub
    End Class  'ProcessSampleMain
End Namespace 'Process_AsyncStream_Sample

Uwagi

StandardOutputStrumień można odczytywać synchronicznie lub asynchronicznie.The StandardOutput stream can be read synchronously or asynchronously. Metody takie jak Read , ReadLine i ReadToEnd wykonują synchroniczne operacje odczytu w strumieniu wyjściowym procesu.Methods such as Read, ReadLine, and ReadToEnd perform synchronous read operations on the output stream of the process. Te synchroniczne operacje odczytu nie są wykonywane do momentu skojarzonego Process zapisu w jego StandardOutput strumieniu lub zamknięcia strumienia.These synchronous read operations do not complete until the associated Process writes to its StandardOutput stream, or closes the stream.

Z kolei program BeginOutputReadLine uruchamia asynchroniczne operacje odczytu w StandardOutput strumieniu.In contrast, BeginOutputReadLine starts asynchronous read operations on the StandardOutput stream. Ta metoda umożliwia wyznaczeniu programu obsługi zdarzeń dla danych wyjściowych strumienia i natychmiast powraca do obiektu wywołującego, który może wykonywać inne czynności, gdy dane wyjściowe strumienia są kierowane do programu obsługi zdarzeń.This method enables a designated event handler for the stream output and immediately returns to the caller, which can perform other work while the stream output is directed to the event handler.

Wykonaj następujące kroki, aby wykonać asynchroniczne operacje odczytu StandardOutput dla Process :Follow these steps to perform asynchronous read operations on StandardOutput for a Process :

  1. Ustaw UseShellExecute wartość false .Set UseShellExecute to false.

  2. Ustaw RedirectStandardOutput wartość true .Set RedirectStandardOutput to true.

  3. Dodaj obsługę zdarzeń do OutputDataReceived zdarzenia.Add your event handler to the OutputDataReceived event. Program obsługi zdarzeń musi być zgodny z System.Diagnostics.DataReceivedEventHandler podpisem delegata.The event handler must match the System.Diagnostics.DataReceivedEventHandler delegate signature.

  4. Uruchom Process .Start the Process.

  5. Wywołanie BeginOutputReadLine Process .Call BeginOutputReadLine for the Process. To wywołanie uruchamia asynchroniczne operacje odczytu w StandardOutput .This call starts asynchronous read operations on StandardOutput.

Po rozpoczęciu asynchronicznych operacji odczytu procedura obsługi zdarzeń jest wywoływana za każdym razem, gdy skojarzone Process zapisuje wiersz tekstu w jego StandardOutput strumieniu.When asynchronous read operations start, the event handler is called each time the associated Process writes a line of text to its StandardOutput stream.

Można anulować asynchroniczne operacje odczytu przez wywołanie CancelOutputRead .You can cancel an asynchronous read operation by calling CancelOutputRead. Operacja odczytu może zostać anulowana przez obiekt wywołujący lub przez procedurę obsługi zdarzeń.The read operation can be canceled by the caller or by the event handler. Po anulowaniu można wywoływać BeginOutputReadLine ponownie w celu wznowienia asynchronicznych operacji odczytu.After canceling, you can call BeginOutputReadLine again to resume asynchronous read operations.

Uwaga

Nie można mieszać asynchronicznych i synchronicznych operacji odczytu w przekierowanym strumieniu.You cannot mix asynchronous and synchronous read operations on a redirected stream. Gdy przekierowany strumień a Process zostanie otwarty w trybie asynchronicznym lub synchronicznym, wszystkie dalsze operacje odczytu w tym strumieniu muszą znajdować się w tym samym trybie.Once the redirected stream of a Process is opened in either asynchronous or synchronous mode, all further read operations on that stream must be in the same mode. Na przykład nie należy śledzić BeginOutputReadLine wywołania do ReadLine StandardOutput strumienia lub na odwrót.For example, do not follow BeginOutputReadLine with a call to ReadLine on the StandardOutput stream, or vice versa. Można jednak odczytywać dwa różne strumienie w różnych trybach.However, you can read two different streams in different modes. Na przykład można wywołać BeginOutputReadLine i wywołać ReadLine StandardError strumień.For example, you can call BeginOutputReadLine and then call ReadLine for the StandardError stream.

Dotyczy

Zobacz też