Process.BeginErrorReadLine Metódus
Definíció
Fontos
Egyes információk olyan, kiadás előtti termékekre vonatkoznak, amelyek a kiadásig még jelentősen módosulhatnak. A Microsoft nem vállal kifejezett vagy törvényi garanciát az itt megjelenő információért.
Aszinkron olvasási műveleteket indít el az alkalmazás átirányított StandardError adatfolyamán.
public:
void BeginErrorReadLine();public void BeginErrorReadLine();[System.Runtime.InteropServices.ComVisible(false)]
public void BeginErrorReadLine();member this.BeginErrorReadLine : unit -> unit[<System.Runtime.InteropServices.ComVisible(false)>]
member this.BeginErrorReadLine : unit -> unitPublic Sub BeginErrorReadLine ()- Attribútumok
Kivételek
A RedirectStandardError tulajdonság false.
-vagy-
Az aszinkron olvasási művelet már folyamatban van a StandardError streamen.
-vagy-
A StandardError streamet szinkron olvasási művelet használta.
Példák
Az alábbi példa a net view parancs használatával listázhatja a távoli számítógépen elérhető hálózati erőforrásokat. A felhasználó parancssori argumentumként adja meg a célszámítógép nevét. A felhasználó fájlnevet is megadhat a hibakimenethez. A példa összegyűjti a net parancs kimenetét, megvárja a folyamat befejezését, majd a kimenet eredményeit a konzolra írja. Ha a felhasználó megadja az opcionális hibafájlt, a példa hibákat ír a fájlba.
// Define the namespaces used by this sample.
using System;
using System.Text;
using System.Globalization;
using System.IO;
using System.Diagnostics;
using System.Threading;
using System.ComponentModel;
namespace ProcessAsyncStreamSamples
{
class ProcessNetStreamRedirection
{
// Define static variables shared by class methods.
private static StreamWriter streamError =null;
private static String netErrorFile = "";
private static StringBuilder netOutput = null;
private static bool errorRedirect = false;
private static bool errorsWritten = false;
public static void RedirectNetCommandStreams()
{
String netArguments;
Process netProcess;
// Get the input computer name.
Console.WriteLine("Enter the computer name for the net view command:");
netArguments = Console.ReadLine().ToUpper(CultureInfo.InvariantCulture);
if (String.IsNullOrEmpty(netArguments))
{
// Default to the help command if there is not an input argument.
netArguments = "/?";
}
// Check if errors should be redirected to a file.
errorsWritten = false;
Console.WriteLine("Enter a fully qualified path to an error log file");
Console.WriteLine(" or just press Enter to write errors to console:");
netErrorFile = Console.ReadLine().ToUpper(CultureInfo.InvariantCulture);
if (!String.IsNullOrEmpty(netErrorFile))
{
errorRedirect = true;
}
// Note that at this point, netArguments and netErrorFile
// are set with user input. If the user did not specify
// an error file, then errorRedirect is set to false.
// Initialize the process and its StartInfo properties.
netProcess = new Process();
netProcess.StartInfo.FileName = "Net.exe";
// Build the net command argument list.
netProcess.StartInfo.Arguments = String.Format("view {0}",
netArguments);
// Set UseShellExecute to false for redirection.
netProcess.StartInfo.UseShellExecute = false;
// Redirect the standard output of the net command.
// This stream is read asynchronously using an event handler.
netProcess.StartInfo.RedirectStandardOutput = true;
netProcess.OutputDataReceived += new DataReceivedEventHandler(NetOutputDataHandler);
netOutput = new StringBuilder();
if (errorRedirect)
{
// Redirect the error output of the net command.
netProcess.StartInfo.RedirectStandardError = true;
netProcess.ErrorDataReceived += new DataReceivedEventHandler(NetErrorDataHandler);
}
else
{
// Do not redirect the error output.
netProcess.StartInfo.RedirectStandardError = false;
}
Console.WriteLine("\nStarting process: net {0}",
netProcess.StartInfo.Arguments);
if (errorRedirect)
{
Console.WriteLine("Errors will be written to the file {0}",
netErrorFile);
}
// Start the process.
netProcess.Start();
// Start the asynchronous read of the standard output stream.
netProcess.BeginOutputReadLine();
if (errorRedirect)
{
// Start the asynchronous read of the standard
// error stream.
netProcess.BeginErrorReadLine();
}
// Let the net command run, collecting the output.
netProcess.WaitForExit();
if (streamError != null)
{
// Close the error file.
streamError.Close();
}
else
{
// Set errorsWritten to false if the stream is not
// open. Either there are no errors, or the error
// file could not be opened.
errorsWritten = false;
}
if (netOutput.Length > 0)
{
// If the process wrote more than just
// white space, write the output to the console.
Console.WriteLine("\nPublic network shares from net view:\n{0}\n",
netOutput);
}
if (errorsWritten)
{
// Signal that the error file had something
// written to it.
String [] errorOutput = File.ReadAllLines(netErrorFile);
if (errorOutput.Length > 0)
{
Console.WriteLine("\nThe following error output was appended to {0}.",
netErrorFile);
foreach (String errLine in errorOutput)
{
Console.WriteLine(" {0}", errLine);
}
}
Console.WriteLine();
}
netProcess.Close();
}
private static void NetOutputDataHandler(object sendingProcess,
DataReceivedEventArgs outLine)
{
// Collect the net view command output.
if (!String.IsNullOrEmpty(outLine.Data))
{
// Add the text to the collected output.
netOutput.Append(Environment.NewLine + " " + outLine.Data);
}
}
private static void NetErrorDataHandler(object sendingProcess,
DataReceivedEventArgs errLine)
{
// Write the error text to the file if there is something
// to write and an error file has been specified.
if (!String.IsNullOrEmpty(errLine.Data))
{
if (!errorsWritten)
{
if (streamError == null)
{
// Open the file.
try
{
streamError = new StreamWriter(netErrorFile, true);
}
catch (Exception e)
{
Console.WriteLine("Could not open error file!");
Console.WriteLine(e.Message.ToString());
}
}
if (streamError != null)
{
// Write a header to the file if this is the first
// call to the error output handler.
streamError.WriteLine();
streamError.WriteLine(DateTime.Now.ToString());
streamError.WriteLine("Net View error output:");
}
errorsWritten = true;
}
if (streamError != null)
{
// Write redirected errors to the file.
streamError.WriteLine(errLine.Data);
streamError.Flush();
}
}
}
}
}
// Define the namespaces used by this sample.
open System
open System.Text
open System.Globalization
open System.IO
open System.Diagnostics
// Define variables shared by functions.
let mutable streamError = Unchecked.defaultof<StreamWriter>
let mutable netErrorFile = ""
let mutable netOutput = StringBuilder()
let mutable errorRedirect = false
let mutable errorsWritten = false
let netOutputDataHandler (sendingProcess: obj) (outLine: DataReceivedEventArgs) =
// Collect the net view command output.
if String.IsNullOrEmpty outLine.Data |> not then
// Add the text to the collected output.
netOutput.Append(Environment.NewLine + " " + outLine.Data) |> ignore
let netErrorDataHandler (sendingProcess: obj) (errLine: DataReceivedEventArgs) =
// Write the error text to the file if there is something
// to write and an error file has been specified.
if String.IsNullOrEmpty errLine.Data |> not then
if not errorsWritten then
if isNull streamError then
// Open the file.
try
streamError <- new StreamWriter(netErrorFile, true)
with e ->
printfn "Could not open error file!"
printfn $"{e.Message}"
if isNull streamError |> not then
// Write a header to the file if this is the first
// call to the error output handler.
streamError.WriteLine()
streamError.WriteLine DateTime.Now
streamError.WriteLine "Net View error output:"
errorsWritten <- true
if isNull streamError |> not then
// Write redirected errors to the file.
streamError.WriteLine errLine.Data
streamError.Flush()
let redirectNetCommandStreams () =
// Get the input computer name.
printfn "Enter the computer name for the net view command:"
let netArguments = stdin.ReadLine().ToUpper CultureInfo.InvariantCulture
// Default to the help command if there is not an input argument.
let netArguments =
if String.IsNullOrEmpty netArguments then
"/?"
else
netArguments
// Check if errors should be redirected to a file.
errorsWritten <- false
printfn "Enter a fully qualified path to an error log file"
printfn " or just press Enter to write errors to console:"
netErrorFile <- stdin.ReadLine().ToUpper CultureInfo.InvariantCulture
if String.IsNullOrEmpty netErrorFile |> not then
errorRedirect <- true
// Note that at this point, netArguments and netErrorFile
// are set with user input. If the user did not specify
// an error file, then errorRedirect is set to false.
// Initialize the process and its StartInfo properties.
let netProcess = new Process()
netProcess.StartInfo.FileName <- "Net.exe"
// Build the net command argument list.
netProcess.StartInfo.Arguments <- $"view {netArguments}"
// Set UseShellExecute to false for redirection.
netProcess.StartInfo.UseShellExecute <- false
// Redirect the standard output of the net command.
// This stream is read asynchronously using an event handler.
netProcess.StartInfo.RedirectStandardOutput <- true
netProcess.OutputDataReceived.AddHandler(DataReceivedEventHandler netOutputDataHandler)
netOutput <- new StringBuilder()
if errorRedirect then
// Redirect the error output of the net command.
netProcess.StartInfo.RedirectStandardError <- true
netProcess.ErrorDataReceived.AddHandler(DataReceivedEventHandler netErrorDataHandler)
else
// Do not redirect the error output.
netProcess.StartInfo.RedirectStandardError <- false
printfn $"\nStarting process: net {netProcess.StartInfo.Arguments}"
if errorRedirect then
printfn $"Errors will be written to the file {netErrorFile}"
// Start the process.
netProcess.Start() |> ignore
// Start the asynchronous read of the standard output stream.
netProcess.BeginOutputReadLine()
if errorRedirect then
// Start the asynchronous read of the standard error stream.
netProcess.BeginErrorReadLine()
// Let the net command run, collecting the output.
netProcess.WaitForExit()
if streamError <> null then
// Close the error file.
streamError.Close()
else
// Set errorsWritten to false if the stream is not
// open. Either there are no errors, or the error
// file could not be opened.
errorsWritten <- false
if netOutput.Length > 0 then
// If the process wrote more than just
// white space, write the output to the console.
printfn $"\nPublic network shares from net view:\n{netOutput}\n"
if errorsWritten then
// Signal that the error file had something
// written to it.
let errorOutput = File.ReadAllLines netErrorFile
if errorOutput.Length > 0 then
printfn $"\nThe following error output was appended to {netErrorFile}."
for errLine in errorOutput do
printfn $" {errLine}"
printfn ""
netProcess.Close()
' Define the namespaces used by this sample.
Imports System.Text
Imports System.Globalization
Imports System.IO
Imports System.Diagnostics
Imports System.Threading
Imports System.ComponentModel
Namespace ProcessAsyncStreamSamples
Class ProcessAsyncErrorRedirection
' Define static variables shared by class methods.
Private Shared streamError As StreamWriter = Nothing
Private Shared netErrorFile As String = ""
Private Shared netOutput As StringBuilder = Nothing
Private Shared errorRedirect As Boolean = False
Private Shared errorsWritten As Boolean = False
Public Shared Sub RedirectNetCommandStreams()
Dim netArguments As String
Dim netProcess As Process
' Get the input computer name.
Console.WriteLine("Enter the computer name for the net view command:")
netArguments = Console.ReadLine().ToUpper(CultureInfo.InvariantCulture)
If String.IsNullOrEmpty(netArguments) Then
' Default to the help command if there is
' not an input argument.
netArguments = "/?"
End If
' Check if errors should be redirected to a file.
errorsWritten = False
Console.WriteLine("Enter a fully qualified path to an error log file")
Console.WriteLine(" or just press Enter to write errors to console:")
netErrorFile = Console.ReadLine().ToUpper(CultureInfo.InvariantCulture)
If Not String.IsNullOrEmpty(netErrorFile) Then
errorRedirect = True
End If
' Note that at this point, netArguments and netErrorFile
' are set with user input. If the user did not specify
' an error file, then errorRedirect is set to false.
' Initialize the process and its StartInfo properties.
netProcess = New Process()
netProcess.StartInfo.FileName = "Net.exe"
' Build the net command argument list.
netProcess.StartInfo.Arguments = String.Format("view {0}", _
netArguments)
' Set UseShellExecute to false for redirection.
netProcess.StartInfo.UseShellExecute = False
' Redirect the standard output of the net command.
' Read the stream asynchronously using an event handler.
netProcess.StartInfo.RedirectStandardOutput = True
AddHandler netProcess.OutputDataReceived, _
AddressOf NetOutputDataHandler
netOutput = new StringBuilder()
If errorRedirect Then
' Redirect the error output of the net command.
netProcess.StartInfo.RedirectStandardError = True
AddHandler netProcess.ErrorDataReceived, _
AddressOf NetErrorDataHandler
Else
' Do not redirect the error output.
netProcess.StartInfo.RedirectStandardError = False
End If
Console.WriteLine(ControlChars.Lf + "Starting process: NET {0}", _
netProcess.StartInfo.Arguments)
If errorRedirect Then
Console.WriteLine("Errors will be written to the file {0}", _
netErrorFile)
End If
' Start the process.
netProcess.Start()
' Start the asynchronous read of the standard output stream.
netProcess.BeginOutputReadLine()
If errorRedirect Then
' Start the asynchronous read of the standard
' error stream.
netProcess.BeginErrorReadLine()
End If
' Let the net command run, collecting the output.
netProcess.WaitForExit()
If Not streamError Is Nothing Then
' Close the error file.
streamError.Close()
Else
' Set errorsWritten to false if the stream is not
' open. Either there are no errors, or the error
' file could not be opened.
errorsWritten = False
End If
If netOutput.Length > 0 Then
' If the process wrote more than just
' white space, write the output to the console.
Console.WriteLine()
Console.WriteLine("Public network shares from net view:")
Console.WriteLine()
Console.WriteLine(netOutput)
Console.WriteLine()
End If
If errorsWritten Then
' Signal that the error file had something
' written to it.
Dim errorOutput As String()
errorOutput = File.ReadAllLines(netErrorFile)
If errorOutput.Length > 0 Then
Console.WriteLine(ControlChars.Lf + _
"The following error output was appended to {0}.", _
netErrorFile)
Dim errLine as String
For Each errLine in errorOutput
Console.WriteLine(" {0}", errLine)
Next
Console.WriteLine()
End If
End If
netProcess.Close()
End Sub
Private Shared Sub NetOutputDataHandler(sendingProcess As Object, _
outLine As DataReceivedEventArgs)
' Collect the net view command output.
If Not String.IsNullOrEmpty(outLine.Data) Then
' Add the text to the collected output.
netOutput.Append(Environment.NewLine + " " + outLine.Data)
End If
End Sub
Private Shared Sub NetErrorDataHandler(sendingProcess As Object, _
errLine As DataReceivedEventArgs)
' Write the error text to the file if there is something to
' write and an error file has been specified.
If Not String.IsNullOrEmpty(errLine.Data) Then
If Not errorsWritten Then
If streamError Is Nothing Then
' Open the file.
Try
streamError = New StreamWriter(netErrorFile, true)
Catch e As Exception
Console.WriteLine("Could not open error file!")
Console.WriteLine(e.Message.ToString())
End Try
End If
If Not streamError Is Nothing Then
' Write a header to the file if this is the first
' call to the error output handler.
streamError.WriteLine()
streamError.WriteLine(DateTime.Now.ToString())
streamError.WriteLine("Net View error output:")
End If
errorsWritten = True
End If
If Not streamError Is Nothing Then
' Write redirected errors to the file.
streamError.WriteLine(errLine.Data)
streamError.Flush()
End If
End If
End Sub
End Class
End Namespace
Megjegyzések
A StandardError stream szinkronban vagy aszinkron módon is olvasható. Az olyan metódusok, mint a Read, ReadLineés ReadToEnd szinkron olvasási műveleteket hajtanak végre a folyamat kimeneti adatfolyamán. Ezek a szinkron olvasási műveletek addig nem fejeződnek be, amíg a társított Process írás nem fejeződik be a streambe StandardError , vagy nem zárja be a streamet.
Ezzel szemben BeginErrorReadLine elindítja az aszinkron olvasási műveleteket a StandardError streamen. Ez a módszer lehetővé teszi a streamkimenethez kijelölt eseménykezelőt, és azonnal visszatér a hívóhoz, amely más műveleteket is végrehajthat, miközben a stream kimenete az eseménykezelőhöz lesz irányítva.
Az alábbi lépéseket követve aszinkron olvasási műveleteket hajthat végre a StandardError következő műveleteken Process :
Állítsa be UseShellExecute-t
false-re.Állítsa be RedirectStandardError-t
true-re.Adja hozzá az eseménykezelőt az ErrorDataReceived eseményhez. Az eseménykezelőnek meg kell egyeznie a meghatalmazott aláírásával System.Diagnostics.DataReceivedEventHandler .
Indítsa el Process.
Hívja meg BeginErrorReadLine a Process. Ez a hívás aszinkron olvasási műveleteket indít el a következőn StandardError: .
Az aszinkron olvasási műveletek indításakor a rendszer minden alkalommal meghívja az eseménykezelőt, amikor a társított Process szövegsort ír a streambe StandardError .
Az aszinkron olvasási műveletet a hívással CancelErrorReadszakíthatja meg. Az olvasási műveletet megszakíthatja a hívó vagy az eseménykezelő. A megszakítás után újra hívhatja BeginErrorReadLine az aszinkron olvasási műveletek folytatását.
Note
Átirányított streamen nem lehet aszinkron és szinkron olvasási műveleteket keverni. Ha egy átirányított stream Process aszinkron vagy szinkron módban van megnyitva, a streamen lévő összes további olvasási műveletnek ugyanabban a módban kell lennie. Például ne kövesse BeginErrorReadLine a streamre ReadLineStandardError irányuló hívásokat, vagy fordítva. Két különböző streamet azonban különböző módokon olvashat. Meghívhatja például, majd meghívhatja BeginErrorReadLineReadLine a streamet StandardOutput .
