Process.CancelOutputRead Metoda
Definice
Důležité
Některé informace platí pro předběžně vydaný produkt, který se může zásadně změnit, než ho výrobce nebo autor vydá. Microsoft neposkytuje žádné záruky, výslovné ani předpokládané, týkající se zde uváděných informací.
Zruší asynchronní operaci čtení u přesměrovaného StandardOutput datového proudu aplikace.
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 ()- Atributy
Výjimky
Stream StandardOutput není povolený pro asynchronní operace čtení.
Příklady
Následující příklad spustí nmake příkaz s zadanými argumenty uživatelem. Chyby a výstupní datové proudy se čtou asynchronně; Shromážděné textové řádky se zobrazí v konzole a zapisují se do souboru protokolu. Pokud výstup příkazu překročí zadaný počet řádků, asynchronní operace čtení se zruší.
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 static variables shared by class methods.
let mutable buildLogStream = Unchecked.defaultof<StreamWriter>
let logMutex = new Mutex()
let mutable maxLogLines = 25
let mutable currentLogLines = 0
let logToFile logPrefix logText echoToConsole =
// Write the specified line to the log file stream.
let logString = StringBuilder()
if String.IsNullOrEmpty logPrefix |> not then
logString.AppendFormat $"{logPrefix}> " |> ignore
if String.IsNullOrEmpty logPrefix |> not then
logString.AppendFormat $"{logPrefix}> " |> ignore
if String.IsNullOrEmpty logText |> not then
logString.Append logText |> ignore
if isNull buildLogStream |> not then
buildLogStream.WriteLine $"[{DateTime.Now}] {logString}"
buildLogStream.Flush()
if echoToConsole then
printfn $"{logString}"
let nMakeOutputDataHandler (sendingProcess: obj) (outLine: 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 String.IsNullOrEmpty outLine.Data |> not then
logMutex.WaitOne() |> ignore
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)
elif currentLogLines = maxLogLines then
logToFile "StdOut" "<Max build log limit reached!>" true
// Stop reading the output streams.
match sendingProcess with
| :? Process as p ->
p.CancelOutputRead()
p.CancelErrorRead()
| _ -> ()
else
// Write the line to the log file.
logToFile "StdOut" outLine.Data true
logMutex.ReleaseMutex()
let nMakeErrorDataHandler (sendingProcess: obj) (errLine: DataReceivedEventArgs) =
// 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 |> not then
logMutex.WaitOne() |> ignore
currentLogLines <- currentLogLines + 1
if currentLogLines > maxLogLines then
// Display the error line to the console.
// Skip writing the line to the log file.
printfn $"StdErr: {errLine.Data}"
elif currentLogLines = maxLogLines then
logToFile "StdErr" "<Max build log limit reached!>" true
// Stop reading the output streams
match sendingProcess with
| :? Process as p ->
p.CancelErrorRead()
p.CancelOutputRead()
| _ -> ()
else
// Write the line to the log file.
logToFile "StdErr" errLine.Data true
logMutex.ReleaseMutex()
let redirectNMakeCommandStreams () =
// Get the input nmake command-line arguments.
printfn "Enter the NMake command line arguments (@commandfile or /f makefile, etc):"
let nmakeArguments = stdin.ReadLine()
printfn "Enter max line limit for log file (default is 25):"
let inputText = Console.ReadLine()
if String.IsNullOrEmpty inputText |> not then
if Int32.TryParse(inputText, &maxLogLines) |> not then
maxLogLines <- 25
printfn $"Output beyond {maxLogLines} lines will be ignored."
// Initialize the process and its StartInfo properties.
let nmakeProcess = new Process()
nmakeProcess.StartInfo.FileName <- "NMake.exe"
// Build the nmake command argument list.
if String.IsNullOrEmpty nmakeArguments |> not then
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.AddHandler(DataReceivedEventHandler nMakeOutputDataHandler)
// Redirect the error output of the nmake command.
nmakeProcess.StartInfo.RedirectStandardError <- true
nmakeProcess.ErrorDataReceived.AddHandler(DataReceivedEventHandler nMakeErrorDataHandler)
logMutex.WaitOne() |> ignore
currentLogLines <- 0
// Write a header to the log file.
let buildLogFile = "NmakeCmd.Txt"
try
buildLogStream <- new StreamWriter(buildLogFile, true)
with e ->
printfn $"Could not open output file {buildLogFile}"
printfn $"Exception = {e}"
printfn $"{e.Message}"
buildLogStream <- null
if isNull buildLogStream |> not then
printfn $"Nmake output logged to {buildLogFile}"
buildLogStream.WriteLine()
buildLogStream.WriteLine DateTime.Now
if String.IsNullOrEmpty nmakeArguments |> not then
buildLogStream.Write $"Command line = NMake {nmakeArguments}"
else
buildLogStream.Write "Command line = Nmake"
buildLogStream.WriteLine()
buildLogStream.Flush()
logMutex.ReleaseMutex()
// Start the process.
Console.WriteLine("\n\nStarting Nmake command...\n")
nmakeProcess.Start() |> ignore
// 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()
' 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
Poznámky
BeginOutputReadLine spustí asynchronní operaci čtení ve streamu StandardOutput . CancelOutputRead ukončí asynchronní operaci čtení.
Po zrušení můžete pokračovat v asynchronních operacích čtení opětovným voláním BeginOutputReadLine .
Při volání CancelOutputReadse dokončí všechny probíhající operace StandardOutput čtení a obslužná rutina události je zakázaná. Veškerý další přesměrovaný výstup se StandardOutput uloží do vyrovnávací paměti. Pokud znovu povolíte obslužnou rutinu události s voláním BeginOutputReadLine, uložený výstup se odešle do obslužné rutiny události a asynchronní operace čtení pokračovat. Pokud chcete před obnovením asynchronních operací čtení změnit obslužnou rutinu události, musíte před přidáním nové obslužné rutiny události odebrat existující obslužnou rutinu události:
// 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();
Note
Asynchronní a synchronní operace čtení u přesměrovaného StandardOutput datového proudu nelze kombinovat. Po otevření přesměrovaného streamu Process v asynchronním nebo synchronním režimu musí být všechny další operace čtení v daném datovém proudu ve stejném režimu. Pokud zrušíte asynchronní operaci StandardOutput čtení a pak potřebujete číst z datového proudu znovu, musíte použít BeginOutputReadLine k obnovení asynchronních operací čtení. Nespočítejte CancelOutputRead s voláním synchronních metod StandardOutput čtení, jako Readje , ReadLinenebo ReadToEnd.
