Process.CancelOutputRead 方法
定義
重要
部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。
在應用程式的重新導向 StandardOutput 資料流上取消非同步讀取作業。
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 ()- 屬性
例外狀況
未因非同步讀取作業之故開啟 StandardOutput 資料流。
範例
下列範例會 nmake 以使用者提供的自變數啟動 命令。 錯誤和輸出數據流會以異步方式讀取;收集的文字行會顯示至主控台，以及寫入記錄檔。 如果命令輸出超過指定的行數，則會取消異步讀取作業。
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
備註
BeginOutputReadLine 在數據流上 StandardOutput 啟動異步讀取作業。 CancelOutputRead 結束異步讀取作業。
取消之後，您可以再次呼叫 BeginOutputReadLine 來繼續異步讀取作業。
當您呼叫 CancelOutputRead時，會完成 的所有進行中讀取作業 StandardOutput ，然後停用事件處理程式。 所有進一步重新導向的輸出 StandardOutput 都會儲存在緩衝區中。 如果您使用呼叫 BeginOutputReadLine重新啟用事件處理程式，則會將儲存的輸出傳送至事件處理程式，並繼續異步讀取作業。 如果您想要在繼續異步讀取作業之前變更事件處理程式，您必須先移除現有的事件處理程式，才能新增事件處理程式：
// 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();
注意
您無法在重新導向 StandardOutput 數據流上混合異步和同步讀取作業。 在異步或同步模式中開啟的 Process 重新導向數據流之後，該數據流上的所有進一步讀取作業都必須處於相同的模式。 如果您取消 上的 StandardOutput 異步讀取作業，然後需要再次從數據流讀取，則必須使用 BeginOutputReadLine 繼續異步讀取作業。 請勿接聽 CancelOutputRead 同步讀取方法 StandardOutput 的呼叫，例如 Read、 ReadLine或 ReadToEnd。
