Process.CancelOutputRead Méthode
Définition
Important
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Annule l'opération de lecture asynchrone sur le flux StandardOutput redirigé d'une application.
public:
void CancelOutputRead();public void CancelOutputRead ();[System.Runtime.InteropServices.ComVisible(false)]
public void CancelOutputRead ();member this.CancelOutputRead : unit -> unit[<System.Runtime.InteropServices.ComVisible(false)>]
member this.CancelOutputRead : unit -> unitPublic Sub CancelOutputRead ()- Attributs
Exceptions
Le flux StandardOutput n’est pas activé pour des opérations de lecture asynchrones.
Exemples
L’exemple suivant démarre la nmake commande avec les arguments fournis par l’utilisateur. Les flux d’erreur et de sortie sont lus de façon asynchrone ; les lignes de texte collectées sont affichées dans la console et écrites dans un fichier journal. Si la sortie de la commande dépasse un nombre spécifié de lignes, les opérations de lecture asynchrones sont annulées.
ref class ProcessNMakeStreamRedirection
{
private:
// Define static variables shared by class methods.
static StreamWriter^ buildLogStream = nullptr;
static Mutex^ logMutex = gcnew Mutex;
static int maxLogLines = 25;
static int currentLogLines = 0;
public:
static void RedirectNMakeCommandStreams()
{
String^ nmakeArguments = nullptr;
Process^ nmakeProcess;
// Get the input nmake command-line arguments.
Console::WriteLine( "Enter the NMake command line arguments (@commandfile or /f makefile, etc):" );
String^ inputText = Console::ReadLine();
if ( !String::IsNullOrEmpty( inputText ) )
{
nmakeArguments = inputText;
}
Console::WriteLine( "Enter max line limit for log file (default is 25):" );
inputText = Console::ReadLine();
if ( !String::IsNullOrEmpty( inputText ) )
{
if ( !Int32::TryParse( inputText, maxLogLines ) )
{
maxLogLines = 25;
}
}
Console::WriteLine( "Output beyond {0} lines will be ignored.",
maxLogLines.ToString() );
// Initialize the process and its StartInfo properties.
nmakeProcess = gcnew Process;
nmakeProcess->StartInfo->FileName = "NMake.exe";
// Build the nmake command argument list.
if ( !String::IsNullOrEmpty( nmakeArguments ) )
{
nmakeProcess->StartInfo->Arguments = nmakeArguments;
}
// Set UseShellExecute to false for redirection.
nmakeProcess->StartInfo->UseShellExecute = false;
// Redirect the standard output of the nmake command.
// Read the stream asynchronously using an event handler.
nmakeProcess->StartInfo->RedirectStandardOutput = true;
nmakeProcess->OutputDataReceived += gcnew DataReceivedEventHandler( NMakeOutputDataHandler );
// Redirect the error output of the nmake command.
nmakeProcess->StartInfo->RedirectStandardError = true;
nmakeProcess->ErrorDataReceived += gcnew DataReceivedEventHandler( NMakeErrorDataHandler );
logMutex->WaitOne();
currentLogLines = 0;
// Write a header to the log file.
String^ buildLogFile = "NmakeCmd.Txt";
try
{
buildLogStream = gcnew StreamWriter( buildLogFile,true );
}
catch ( Exception^ e )
{
Console::WriteLine( "Could not open output file {0}", buildLogFile );
Console::WriteLine( "Exception = {0}", e->ToString() );
Console::WriteLine( e->Message->ToString() );
buildLogStream = nullptr;
}
if ( buildLogStream != nullptr )
{
Console::WriteLine( "Nmake output logged to {0}", buildLogFile );
buildLogStream->WriteLine();
buildLogStream->WriteLine( DateTime::Now.ToString() );
if ( !String::IsNullOrEmpty( nmakeArguments ) )
{
buildLogStream->Write( "Command line = NMake {0}", nmakeArguments );
}
else
{
buildLogStream->Write( "Command line = Nmake" );
}
buildLogStream->WriteLine();
buildLogStream->Flush();
logMutex->ReleaseMutex();
// Start the process.
Console::WriteLine();
Console::WriteLine( "\nStarting Nmake command" );
Console::WriteLine();
nmakeProcess->Start();
// Start the asynchronous read of the output stream.
nmakeProcess->BeginOutputReadLine();
// Start the asynchronous read of the error stream.
nmakeProcess->BeginErrorReadLine();
// Let the nmake command run, collecting the output.
nmakeProcess->WaitForExit();
nmakeProcess->Close();
buildLogStream->Close();
logMutex->Dispose();
}
}
private:
static void NMakeOutputDataHandler( Object^ sendingProcess,
DataReceivedEventArgs^ outLine )
{
// Collect the output, displaying it to the screen and
// logging it to the output file. Cancel the read
// operation when the maximum line limit is reached.
if ( !String::IsNullOrEmpty( outLine->Data ) )
{
logMutex->WaitOne();
currentLogLines++;
if ( currentLogLines > maxLogLines )
{
// Display the line to the console.
// Skip writing the line to the log file.
Console::WriteLine( "StdOut: {0}", outLine->Data->ToString() );
}
else
if ( currentLogLines == maxLogLines )
{
LogToFile( "StdOut", "<Max build log limit reached!>", true );
// Stop reading the output streams.
Process^ p = dynamic_cast<Process^>(sendingProcess);
if ( p != nullptr )
{
p->CancelOutputRead();
p->CancelErrorRead();
}
}
else
{
// Write the line to the log file.
LogToFile( "StdOut", outLine->Data, true );
}
logMutex->ReleaseMutex();
}
}
static void NMakeErrorDataHandler( Object^ sendingProcess,
DataReceivedEventArgs^ errLine )
{
// Collect the error output, displaying it to the screen and
// logging it to the output file. Cancel the error output
// read operation when the maximum line limit is reached.
if ( !String::IsNullOrEmpty( errLine->Data ) )
{
logMutex->WaitOne();
currentLogLines++;
if ( currentLogLines > maxLogLines )
{
// Display the line to the console.
// Skip writing the line to the log file.
Console::WriteLine( "StdErr: {0}", errLine->Data->ToString() );
}
else
if ( currentLogLines == maxLogLines )
{
LogToFile( "StdOut", "<Max build log limit reached!>", true );
// Stop reading the output streams.
Process^ p = dynamic_cast<Process^>(sendingProcess);
if ( p != nullptr )
{
p->CancelOutputRead();
p->CancelErrorRead();
}
}
else
{
// Write the line to the log file.
LogToFile( "StdErr", errLine->Data, true );
}
logMutex->ReleaseMutex();
}
}
static void LogToFile( String^ logPrefix, String^ logText,
bool echoToConsole )
{
// Write the specified line to the log file stream.
StringBuilder^ logString = gcnew StringBuilder;
if ( !String::IsNullOrEmpty( logPrefix ) )
{
logString->AppendFormat( "{0}> ", logPrefix );
}
if ( !String::IsNullOrEmpty( logText ) )
{
logString->Append( logText );
}
if ( buildLogStream != nullptr )
{
buildLogStream->WriteLine( "[{0}] {1}",
DateTime::Now.ToString(), logString->ToString() );
buildLogStream->Flush();
}
if ( echoToConsole )
{
Console::WriteLine( logString->ToString() );
}
}
};
namespace ProcessAsyncStreamSamples
{
class ProcessNMakeStreamRedirection
{
// Define static variables shared by class methods.
private static StreamWriter buildLogStream =null;
private static Mutex logMutex = new Mutex();
private static int maxLogLines = 25;
private static int currentLogLines = 0;
public static void RedirectNMakeCommandStreams()
{
String nmakeArguments = null;
Process nmakeProcess;
// Get the input nmake command-line arguments.
Console.WriteLine("Enter the NMake command line arguments " +
"(@commandfile or /f makefile, etc):");
String inputText = Console.ReadLine();
if (!String.IsNullOrEmpty(inputText))
{
nmakeArguments = inputText;
}
Console.WriteLine("Enter max line limit for log file (default is 25):");
inputText = Console.ReadLine();
if (!String.IsNullOrEmpty(inputText))
{
if (!Int32.TryParse(inputText, out maxLogLines))
{
maxLogLines = 25;
}
}
Console.WriteLine("Output beyond {0} lines will be ignored.",
maxLogLines);
// Initialize the process and its StartInfo properties.
nmakeProcess = new Process();
nmakeProcess.StartInfo.FileName = "NMake.exe";
// Build the nmake command argument list.
if (!String.IsNullOrEmpty(nmakeArguments))
{
nmakeProcess.StartInfo.Arguments = nmakeArguments;
}
// Set UseShellExecute to false for redirection.
nmakeProcess.StartInfo.UseShellExecute = false;
// Redirect the standard output of the nmake command.
// Read the stream asynchronously using an event handler.
nmakeProcess.StartInfo.RedirectStandardOutput = true;
nmakeProcess.OutputDataReceived += new DataReceivedEventHandler(NMakeOutputDataHandler);
// Redirect the error output of the nmake command.
nmakeProcess.StartInfo.RedirectStandardError = true;
nmakeProcess.ErrorDataReceived += new DataReceivedEventHandler(NMakeErrorDataHandler);
logMutex.WaitOne();
currentLogLines = 0;
// Write a header to the log file.
const String buildLogFile = "NmakeCmd.Txt";
try
{
buildLogStream = new StreamWriter(buildLogFile, true);
}
catch (Exception e)
{
Console.WriteLine("Could not open output file {0}", buildLogFile);
Console.WriteLine("Exception = {0}", e.ToString());
Console.WriteLine(e.Message);
buildLogStream = null;
}
if (buildLogStream != null)
{
Console.WriteLine("Nmake output logged to {0}",
buildLogFile);
buildLogStream.WriteLine();
buildLogStream.WriteLine(DateTime.Now.ToString());
if (!String.IsNullOrEmpty(nmakeArguments))
{
buildLogStream.Write("Command line = NMake {0}",
nmakeArguments);
}
else
{
buildLogStream.Write("Command line = Nmake");
}
buildLogStream.WriteLine();
buildLogStream.Flush();
logMutex.ReleaseMutex();
// Start the process.
Console.WriteLine();
Console.WriteLine("\nStarting Nmake command...");
Console.WriteLine();
nmakeProcess.Start();
// Start the asynchronous read of the error stream.
nmakeProcess.BeginErrorReadLine();
// Start the asynchronous read of the output stream.
nmakeProcess.BeginOutputReadLine();
// Let the nmake command run, collecting the output.
nmakeProcess.WaitForExit();
nmakeProcess.Close();
buildLogStream.Close();
logMutex.Dispose();
}
}
private static void NMakeOutputDataHandler(object sendingProcess,
DataReceivedEventArgs outLine)
{
// Collect the output, displaying it to the screen and
// logging it to the output file. Cancel the read
// operation when the maximum line limit is reached.
if (!String.IsNullOrEmpty(outLine.Data))
{
logMutex.WaitOne();
currentLogLines++;
if (currentLogLines > maxLogLines)
{
// Display the line to the console.
// Skip writing the line to the log file.
Console.WriteLine("StdOut: {0}", outLine.Data);
}
else if (currentLogLines == maxLogLines)
{
LogToFile("StdOut", "<Max build log limit reached!>",
true);
// Stop reading the output streams.
Process p = sendingProcess as Process;
if (p != null)
{
p.CancelOutputRead();
p.CancelErrorRead();
}
}
else
{
// Write the line to the log file.
LogToFile("StdOut", outLine.Data, true);
}
logMutex.ReleaseMutex();
}
}
private static void NMakeErrorDataHandler(object sendingProcess,
DataReceivedEventArgs errLine)
{
// Collect error output, displaying it to the screen and
// logging it to the output file. Cancel the error output
// read operation when the maximum line limit is reached.
if (!String.IsNullOrEmpty(errLine.Data))
{
logMutex.WaitOne();
currentLogLines++;
if (currentLogLines > maxLogLines)
{
// Display the error line to the console.
// Skip writing the line to the log file.
Console.WriteLine("StdErr: {0}", errLine.Data);
}
else if (currentLogLines == maxLogLines)
{
LogToFile("StdErr", "<Max build log limit reached!>",
true);
// Stop reading the output streams
Process p = sendingProcess as Process;
if (p != null)
{
p.CancelErrorRead();
p.CancelOutputRead();
}
}
else
{
// Write the line to the log file.
LogToFile("StdErr", errLine.Data, true);
}
logMutex.ReleaseMutex();
}
}
private static void LogToFile(String logPrefix,
String logText, bool echoToConsole)
{
// Write the specified line to the log file stream.
StringBuilder logString = new StringBuilder();
if (!String.IsNullOrEmpty(logPrefix))
{
logString.AppendFormat("{0}> ", logPrefix);
}
if (!String.IsNullOrEmpty(logText))
{
logString.Append(logText);
}
if (buildLogStream != null)
{
buildLogStream.WriteLine("[{0}] {1}",
DateTime.Now.ToString(), logString.ToString());
buildLogStream.Flush();
}
if (echoToConsole)
{
Console.WriteLine(logString.ToString());
}
}
}
}
' Define the namespaces used by this sample.
Imports System.Text
Imports System.IO
Imports System.Diagnostics
Imports System.Threading
Imports System.ComponentModel
Class ProcessNMakeStreamRedirection
' Define static variables shared by class methods.
Private Shared buildLogStream As StreamWriter = Nothing
Private Shared logMutex As Mutex = New Mutex()
Private Shared maxLogLines As Integer = 25
Private Shared currentLogLines As Integer = 0
Public Shared Sub RedirectNMakeCommandStreams()
Dim nmakeArguments As String = Nothing
Dim nmakeProcess As Process
' Get the input nmake command-line arguments.
Console.WriteLine("Enter the NMake command line arguments" + _
" (@commandfile or /f makefile, etc):")
Dim inputText As String = Console.ReadLine()
If Not String.IsNullOrEmpty(inputText) Then
nmakeArguments = inputText
End If
Console.WriteLine("Enter max line limit for log file (default is 25):")
inputText = Console.ReadLine()
If Not String.IsNullOrEmpty(inputText) Then
If Not Int32.TryParse(inputText, maxLogLines) Then
maxLogLines = 25
End If
End If
Console.WriteLine("Output beyond {0} lines will be ignored.", _
maxLogLines)
' Initialize the process and its StartInfo properties.
nmakeProcess = New Process()
nmakeProcess.StartInfo.FileName = "NMake.exe"
' Build the nmake command argument list.
If Not String.IsNullOrEmpty(nmakeArguments) Then
nmakeProcess.StartInfo.Arguments = nmakeArguments
End If
' Set UseShellExecute to false for redirection.
nmakeProcess.StartInfo.UseShellExecute = False
' Redirect the standard output of the nmake command.
' Read the stream asynchronously using an event handler.
nmakeProcess.StartInfo.RedirectStandardOutput = True
AddHandler nmakeProcess.OutputDataReceived, _
AddressOf NMakeOutputDataHandler
' Redirect the error output of the nmake command.
nmakeProcess.StartInfo.RedirectStandardError = True
AddHandler nmakeProcess.ErrorDataReceived, _
AddressOf NMakeErrorDataHandler
logMutex.WaitOne()
currentLogLines = 0
' Write a header to the log file.
Const buildLogFile As String = "NmakeCmd.Txt"
Try
buildLogStream = new StreamWriter(buildLogFile, true)
Catch e As Exception
Console.WriteLine("Could not open output file {0}", buildLogFile)
Console.WriteLine("Exception = {0}", e.ToString())
Console.WriteLine(e.Message)
buildLogStream = Nothing
End Try
If Not buildLogStream Is Nothing Then
Console.WriteLine("Nmake output logged to {0}", _
buildLogFile)
buildLogStream.WriteLine()
buildLogStream.WriteLine(DateTime.Now.ToString())
If Not String.IsNullOrEmpty(nmakeArguments) Then
buildLogStream.Write("Command line = NMake {0}", _
nmakeArguments)
Else
buildLogStream.Write("Command line = Nmake")
End If
buildLogStream.WriteLine()
buildLogStream.Flush()
logMutex.ReleaseMutex()
' Start the process.
Console.WriteLine()
Console.WriteLine("\nStarting Nmake command...")
Console.WriteLine()
nmakeProcess.Start()
' Start the asynchronous read of the error stream.
nmakeProcess.BeginErrorReadLine()
' Start the asynchronous read of the output stream.
nmakeProcess.BeginOutputReadLine()
' Let the nmake command run, collecting the output.
nmakeProcess.WaitForExit()
nmakeProcess.Close()
buildLogStream.Close()
logMutex.Dispose()
End If
End Sub
Private Shared Sub NMakeOutputDataHandler(sendingProcess As Object, _
outLine As DataReceivedEventArgs)
' Collect the output, displaying it to the screen and
' logging it to the output file. Cancel the read
' operation when the maximum line limit is reached.
If Not String.IsNullOrEmpty(outLine.Data) Then
logMutex.WaitOne()
currentLogLines = currentLogLines + 1
If currentLogLines > maxLogLines Then
' Display the line to the console.
' Skip writing the line to the log file.
Console.WriteLine("StdOut: {0}", outLine.Data)
Else If currentLogLines = maxLogLines Then
LogToFile("StdOut", "<Max build log limit reached!>", _
true)
' Stop reading the output streams.
Dim p As Process = sendingProcess
If Not (p Is Nothing) Then
p.CancelOutputRead()
p.CancelErrorRead()
End If
Else
' Write the line to the log file.
LogToFile("StdOut", outLine.Data, true)
End If
logMutex.ReleaseMutex()
End If
End Sub
Private Shared Sub NMakeErrorDataHandler(sendingProcess As Object, _
errLine As DataReceivedEventArgs)
' Collect the error output, displaying it to the screen and
' logging it to the output file. Cancel the error output
' read operation when the maximum line limit is reached.
If Not String.IsNullOrEmpty(errLine.Data) Then
logMutex.WaitOne()
currentLogLines = currentLogLines + 1
If currentLogLines > maxLogLines Then
' Display the line to the console.
' Skip writing the line to the log file.
Console.WriteLine("StdErr: {0}", errLine.Data)
Else If currentLogLines = maxLogLines Then
LogToFile("StdErr", "<Max build log limit reached!>", _
true)
' Stop reading the output streams.
Dim p As Process = sendingProcess
If Not (p Is Nothing) Then
p.CancelOutputRead()
p.CancelErrorRead()
End If
Else
' Write the line to the log file.
LogToFile("StdErr", errLine.Data, true)
End If
logMutex.ReleaseMutex()
End If
End Sub
Private Shared Sub LogToFile(logPrefix As String, _
logText As String, _
echoToConsole As String)
' Write the specified line to the log file stream.
Dim logString As StringBuilder = New StringBuilder()
If Not String.IsNullOrEmpty(logPrefix) Then
logString.AppendFormat("{0}> ", logPrefix)
End If
If Not String.IsNullOrEmpty(logText) Then
logString.Append(logText)
End If
If Not buildLogStream Is Nothing Then
buildLogStream.WriteLine("[{0}] {1}", _
DateTime.Now.ToString(), logString.ToString())
buildLogStream.Flush()
End If
If echoToConsole Then
Console.WriteLine(logString.ToString())
End If
End Sub
End Class
Remarques
BeginOutputReadLine démarre une opération de lecture asynchrone sur le StandardOutput flux. CancelOutputRead termine l’opération de lecture asynchrone.
Après l’annulation, vous pouvez reprendre les opérations de lecture asynchrones en appelant BeginOutputReadLine à nouveau.
Lorsque vous appelez CancelOutputRead, toutes les opérations de lecture en cours pour StandardOutput sont terminées, puis le gestionnaire d’événements est désactivé. Toutes les autres sorties redirigées vers StandardOutput sont enregistrées dans une mémoire tampon. Si vous réactivez le gestionnaire d’événements avec un appel à BeginOutputReadLine, la sortie enregistrée est envoyée au gestionnaire d’événements et les opérations de lecture asynchrones reprennent. Si vous souhaitez modifier le gestionnaire d’événements avant de reprendre les opérations de lecture asynchrones, vous devez supprimer le gestionnaire d’événements existant avant d’ajouter le nouveau gestionnaire d’événements :
// At this point the DataReceivedEventHandler(OutputHandler1)
// has executed a CancelOutputRead.
// Remove the prior event handler.
process.OutputDataReceived -=
new DataReceivedEventHandler(OutputHandler1);
// Register a new event handler.
process.OutputDataReceived +=
new DataReceivedEventHandler(OutputHandler2);
// Call the corresponding BeginOutputReadLine.
process.BeginOutputReadLine();
Notes
Vous ne pouvez pas combiner des opérations de lecture asynchrones et synchrones sur le flux redirigé StandardOutput . Une fois que le flux redirigé d’un Process est ouvert en mode asynchrone ou synchrone, toutes les opérations de lecture supplémentaires sur ce flux doivent être dans le même mode. Si vous annulez une opération de lecture asynchrone sur StandardOutput et que vous devez ensuite lire à nouveau à partir du flux, vous devez utiliser BeginOutputReadLine pour reprendre les opérations de lecture asynchrones. Ne suivez CancelOutputRead pas avec un appel aux méthodes de lecture synchrone de StandardOutput telles que Read, ReadLineou ReadToEnd.
S’applique à
Voir aussi
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