Process.CancelOutputRead Metodo
Definizione
Importante
Alcune informazioni sono relative alla release non definitiva del prodotto, che potrebbe subire modifiche significative prima della release definitiva. Microsoft non riconosce alcuna garanzia, espressa o implicita, in merito alle informazioni qui fornite.
Annulla l'operazione di lettura asincrona sul flusso StandardOutput reindirizzato di un'applicazione.
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 ()- Attributi
Eccezioni
Il flusso StandardOutput non è abilitato per le operazioni di lettura asincrona.
Esempio
Nell'esempio seguente viene avviato il nmake comando con argomenti forniti dall'utente. I flussi di errore e output vengono letti in modo asincrono; le righe di testo raccolte vengono visualizzate nella console e scritte in un file di log. Se l'output del comando supera un numero specificato di righe, le operazioni di lettura asincrone vengono annullate.
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
Commenti
BeginOutputReadLine avvia un'operazione di lettura asincrona nel StandardOutput flusso. CancelOutputRead termina l'operazione di lettura asincrona.
Dopo l'annullamento, è possibile riprendere le operazioni di lettura asincrone chiamando BeginOutputReadLine di nuovo .
Quando si chiama CancelOutputRead, tutte le operazioni di lettura in corso per StandardOutput vengono completate e quindi il gestore eventi è disabilitato. Tutto l'output StandardOutput reindirizzato a viene salvato in un buffer. Se si riabilita il gestore eventi con una chiamata a BeginOutputReadLine, l'output salvato viene inviato al gestore eventi e le operazioni di lettura asincrone riprendono. Se si desidera modificare il gestore eventi prima di riprendere le operazioni di lettura asincrone, è necessario rimuovere il gestore eventi esistente prima di aggiungere il nuovo gestore eventi:
// 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();
Nota
Non è possibile combinare operazioni di lettura asincrone e sincrone nel flusso reindirizzato StandardOutput . Dopo l'apertura del flusso reindirizzato di un Process oggetto in modalità asincrona o sincrona, tutte le altre operazioni di lettura su tale flusso devono trovarsi nella stessa modalità. Se si annulla un'operazione di lettura asincrona su StandardOutput e quindi è necessario leggere di nuovo dal flusso, è necessario usare BeginOutputReadLine per riprendere le operazioni di lettura asincrone. Non seguire CancelOutputRead con una chiamata ai metodi di lettura sincroni di StandardOutput , Readad esempio , ReadLineo ReadToEnd.
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