Process.BeginOutputReadLine Método

Definición

Inicia las operaciones de lectura asincrónica en la secuencia de StandardOutput redirigida de la aplicación.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 ()
Atributos

Excepciones

La propiedad RedirectStandardOutput es false.The RedirectStandardOutput property is false.

o bien-or- Ya hay una operación de lectura asincrónica en curso en la secuencia StandardOutput.An asynchronous read operation is already in progress on the StandardOutput stream.

o bien-or- Una operación de lectura sincrónica ha utilizado la secuencia StandardOutput.The StandardOutput stream has been used by a synchronous read operation.

Ejemplos

En el ejemplo siguiente se muestra cómo realizar operaciones de lectura asincrónica en la secuencia redirigida StandardOutput del sort comando.The following example illustrates how to perform asynchronous read operations on the redirected StandardOutput stream of the sort command. El sort comando es una aplicación de consola que lee y ordena la entrada de texto.The sort command is a console application that reads and sorts text input.

En el ejemplo se crea un delegado de eventos para el SortOutputHandler controlador de eventos y se asocia al OutputDataReceived evento.The example creates an event delegate for the SortOutputHandler event handler and associates it with the OutputDataReceived event. El controlador de eventos recibe líneas de texto de la secuencia redirigida StandardOutput , da formato al texto y escribe el texto en la pantalla.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

Comentarios

La StandardOutput secuencia se puede leer de forma sincrónica o asincrónica.The StandardOutput stream can be read synchronously or asynchronously. Los métodos como Read , ReadLine y ReadToEnd realizan operaciones de lectura sincrónicas en el flujo de salida del proceso.Methods such as Read, ReadLine, and ReadToEnd perform synchronous read operations on the output stream of the process. Estas operaciones de lectura sincrónicas no se completan hasta que el Process objeto asociado escribe en su StandardOutput secuencia o cierra la secuencia.These synchronous read operations do not complete until the associated Process writes to its StandardOutput stream, or closes the stream.

En cambio, BeginOutputReadLine inicia las operaciones de lectura asincrónica en la StandardOutput secuencia.In contrast, BeginOutputReadLine starts asynchronous read operations on the StandardOutput stream. Este método habilita un controlador de eventos designado para la salida de flujo y vuelve inmediatamente al llamador, que puede realizar otro trabajo mientras la salida de flujo se dirige al controlador de eventos.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.

Siga estos pasos para realizar operaciones de lectura asincrónica en StandardOutput para un Process :Follow these steps to perform asynchronous read operations on StandardOutput for a Process :

  1. Establezca UseShellExecute en false.Set UseShellExecute to false.

  2. Establezca RedirectStandardOutput en true.Set RedirectStandardOutput to true.

  3. Agregue el controlador de eventos al OutputDataReceived evento.Add your event handler to the OutputDataReceived event. El controlador de eventos debe coincidir con la System.Diagnostics.DataReceivedEventHandler firma del delegado.The event handler must match the System.Diagnostics.DataReceivedEventHandler delegate signature.

  4. Inicie la Process.Start the Process.

  5. Llame a BeginOutputReadLine para Process .Call BeginOutputReadLine for the Process. Esta llamada inicia las operaciones de lectura asincrónicas en StandardOutput .This call starts asynchronous read operations on StandardOutput.

Cuando se inician las operaciones de lectura asincrónica, se llama al controlador de eventos cada vez que el asociado Process escribe una línea de texto en su StandardOutput secuencia.When asynchronous read operations start, the event handler is called each time the associated Process writes a line of text to its StandardOutput stream.

Puede cancelar una operación de lectura asincrónica mediante una llamada a CancelOutputRead .You can cancel an asynchronous read operation by calling CancelOutputRead. El autor de la llamada o el controlador de eventos pueden cancelar la operación de lectura.The read operation can be canceled by the caller or by the event handler. Después de la cancelación, puede volver a llamar BeginOutputReadLine a para reanudar las operaciones de lectura asincrónicas.After canceling, you can call BeginOutputReadLine again to resume asynchronous read operations.

Nota

No se pueden mezclar operaciones de lectura asincrónicas y sincrónicas en una secuencia redirigida.You cannot mix asynchronous and synchronous read operations on a redirected stream. Una vez que la secuencia redirigida de un Process se abre en modo asincrónico o sincrónico, todas las demás operaciones de lectura en esa secuencia deben estar en el mismo modo.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. Por ejemplo, no siga BeginOutputReadLine con una llamada a ReadLine en el StandardOutput flujo, o viceversa.For example, do not follow BeginOutputReadLine with a call to ReadLine on the StandardOutput stream, or vice versa. Sin embargo, puede leer dos flujos diferentes en distintos modos.However, you can read two different streams in different modes. Por ejemplo, puede llamar a BeginOutputReadLine y, a continuación, llamar a ReadLine para la StandardError secuencia.For example, you can call BeginOutputReadLine and then call ReadLine for the StandardError stream.

Se aplica a

Consulte también