Process.BeginOutputReadLine Methode

Definition

Startet asynchrone Lesevorgänge im umgeleiteten StandardOutput-Stream der Anwendung.Begins asynchronous read operations on the redirected StandardOutput stream of the application.

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

Ausnahmen

Die RedirectStandardOutput-Eigenschaft ist false.The RedirectStandardOutput property is false.

- oder --or- Für den StandardOutput-Stream wird bereits ein asynchroner Lesevorgang ausgeführt.An asynchronous read operation is already in progress on the StandardOutput stream.

- oder --or- Der StandardOutput-Stream wurde von einem synchronen Lesevorgang verwendet.The StandardOutput stream has been used by a synchronous read operation.

Beispiele

Im folgenden Beispiel wird veranschaulicht, wie asynchrone Lesevorgänge für den umgeleiteten StandardOutput Stream des sort-Befehls durchgeführt werden.The following example illustrates how to perform asynchronous read operations on the redirected StandardOutput stream of the sort command. Der Befehl "sort" ist eine Konsolenanwendung zum Lesen und Sortieren von Texteingaben.The sort command is a console application that reads and sorts text input.

Im Beispiel wird ein Ereignis Delegat für den SortOutputHandler Ereignishandler erstellt und dem OutputDataReceived-Ereignis zugeordnet.The example creates an event delegate for the SortOutputHandler event handler and associates it with the OutputDataReceived event. Der Ereignishandler empfängt Textzeilen aus dem umgeleiteten StandardOutput Stream, formatiert den Text und schreibt den Text auf den Bildschirm.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

Hinweise

Der StandardOutput Datenstrom kann synchron oder asynchron gelesen werden.The StandardOutput stream can be read synchronously or asynchronously. Methoden wie Read, ReadLine und ReadToEnd führen synchrone Lesevorgänge für den Ausgabestream des Prozesses aus.Methods such as Read, ReadLine, and ReadToEnd perform synchronous read operations on the output stream of the process. Diese synchronen Lesevorgänge werden erst abgeschlossen, wenn die zugeordnete Process in den StandardOutput-Stream schreibt oder den Stream schließt.These synchronous read operations do not complete until the associated Process writes to its StandardOutput stream, or closes the stream.

Im Gegensatz dazu startet BeginOutputReadLine asynchrone Lesevorgänge für den StandardOutput-Stream.In contrast, BeginOutputReadLine starts asynchronous read operations on the StandardOutput stream. Diese Methode aktiviert einen festgelegten Ereignishandler für die Datenstrom Ausgabe und kehrt sofort an den Aufrufer zurück, der andere Aufgaben ausführen kann, während die Datenstrom Ausgabe an den Ereignishandler weitergeleitet wird.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.

Führen Sie die folgenden Schritte aus, um asynchrone Lesevorgänge für StandardOutput für eine Process auszuführen:Follow these steps to perform asynchronous read operations on StandardOutput for a Process :

  1. Legen Sie UseShellExecute auf false fest.Set UseShellExecute to false.

  2. Legen Sie RedirectStandardOutput auf true fest.Set RedirectStandardOutput to true.

  3. Fügen Sie dem OutputDataReceived-Ereignis den Ereignishandler hinzu.Add your event handler to the OutputDataReceived event. Der Ereignishandler muss mit der System.Diagnostics.DataReceivedEventHandler Delegatsignatur identisch sein.The event handler must match the System.Diagnostics.DataReceivedEventHandler delegate signature.

  4. Starten Sie die Process.Start the Process.

  5. Ruft BeginOutputReadLine für die Processauf.Call BeginOutputReadLine for the Process. Dieser Befehl startet asynchrone Lesevorgänge auf StandardOutput.This call starts asynchronous read operations on StandardOutput.

Wenn asynchrone Lesevorgänge gestartet werden, wird der Ereignishandler jedes Mal aufgerufen, wenn die zugeordnete Process eine Textzeile in den StandardOutput-Stream schreibt.When asynchronous read operations start, the event handler is called each time the associated Process writes a line of text to its StandardOutput stream.

Sie können einen asynchronen Lesevorgang abbrechen, indem Sie CancelOutputReadaufrufen.You can cancel an asynchronous read operation by calling CancelOutputRead. Der Lesevorgang kann vom Aufrufer oder vom Ereignishandler abgebrochen werden.The read operation can be canceled by the caller or by the event handler. Nach dem abbrechen können Sie BeginOutputReadLine erneut aufzurufen, um asynchrone Lesevorgänge fortzusetzen.After canceling, you can call BeginOutputReadLine again to resume asynchronous read operations.

Hinweis

Asynchrone und synchrone Lesevorgänge können nicht in einem umgeleiteten Stream gemischt werden.You cannot mix asynchronous and synchronous read operations on a redirected stream. Sobald der umgeleitete Stream einer Process entweder im asynchronen oder im synchronen Modus geöffnet ist, müssen sich alle weiteren Lesevorgänge in diesem Stream im gleichen Modus befinden.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. Befolgen Sie z. b. BeginOutputReadLine nicht, wenn Sie ReadLine im StandardOutput Stream aufrufen oder umgekehrt.For example, do not follow BeginOutputReadLine with a call to ReadLine on the StandardOutput stream, or vice versa. Sie können jedoch zwei verschiedene Streams in verschiedenen Modi lesen.However, you can read two different streams in different modes. Beispielsweise können Sie BeginOutputReadLine aufzurufen und dann ReadLine für den StandardError Stream aufzurufen.For example, you can call BeginOutputReadLine and then call ReadLine for the StandardError stream.

Sicherheit

LinkDemand
für volle Vertrauenswürdigkeit für den unmittelbaren Aufrufer.for full trust for the immediate caller. Dieser Member kann von nur teilweise vertrauenswürdigem Code nicht verwendet werden.This member cannot be used by partially trusted code.

Gilt für:

Siehe auch