Process.BeginErrorReadLine メソッド

.NET Framework クラス ライブラリ リファレンス

Process.BeginErrorReadLine メソッド

メモ : このメソッドは、.NET Framework version 2.0 で新しく追加されたものです。

アプリケーションのリダイレクトされた StandardError ストリームで、非同期読み取り操作を開始します。

名前空間: System.Diagnostics
アセンブリ: System (system.dll 内)
構文

Visual Basic (宣言)

<ComVisibleAttribute(False)> _
Public Sub BeginErrorReadLine

Visual Basic (使用法)

Dim instance As Process

instance.BeginErrorReadLine

C#

[ComVisibleAttribute(false)] 
public void BeginErrorReadLine ()

C++

[ComVisibleAttribute(false)] 
public:
void BeginErrorReadLine ()

J#

/** @attribute ComVisibleAttribute(false) */ 
public void BeginErrorReadLine ()

JScript

ComVisibleAttribute(false) 
public function BeginErrorReadLine ()

例外

例外の種類	条件
InvalidOperationException	ProcessStartInfo.RedirectStandardError プロパティが false です。 または 非同期読み取り操作は、既に StandardError ストリームで実行中です。 または StandardError ストリームは、非同期読み取り操作によって使用されています。

解説

StandardError ストリームの読み取りは、同期または非同期で実行できます。Read、ReadLine、および ReadToEnd のようなメソッドは、プロセスのエラー出力ストリームで同期読み取り操作を実行します。これらの同期読み取り操作は、関連する Process がその StandardError ストリームに書き込むか、ストリームを閉じるまで完了しません。

対照的に、BeginErrorReadLine は StandardError ストリームで非同期読み取り操作を開始します。このメソッドは、ストリーム出力に指定されたイベント ハンドラを有効にした後、直ちに呼び出し元に制御を返します。これにより、呼び出し元は、ストリーム出力がイベント ハンドラにリダイレクトされている間に他の作業を実行できます。

次の手順に従い、Process の StandardError で非同期読み取り操作を実行してください。

1. UseShellExecute を false に設定します。

2. RedirectStandardError を true に設定します。

3. ErrorDataReceived イベントにイベント ハンドラを追加します。イベント ハンドラは、System.Diagnostics.DataReceivedEventHandler デリゲート シグネチャと一致する必要があります。

4. Process を開始します。

5. Process の BeginErrorReadLine を呼び出します。この呼び出しにより、非同期読み取り操作が StandardError で開始されます。

非同期読み取り操作が開始されると、関連付けられた Process がテキストの行を StandardError ストリームに書き込むたびにイベント ハンドラが呼び出されます。

非同期読み取り操作をキャンセルするには、CancelErrorRead を呼び出します。読み取り操作は、呼び出し元またはイベント ハンドラによってキャンセルできます。キャンセル後に非同期読み取り操作を再開するには、BeginErrorReadLine を再度呼び出します。

メモ
リダイレクトされたストリームで、非同期読み取り操作と同期読み取り操作を混在させることはできません。Process のリダイレクトされたストリームを非同期モードまたは同期モードで開いた後は、それ以降、そのストリームに対するすべての読み取り操作は同じモードで行う必要があります。たとえば、StandardError で BeginErrorReadLine の後に ReadLine の呼び出しを続けないでください。逆も同様です。ただし、2 つの異なるストリームをそれぞれ別のモードで読み取ることはできます。たとえば、BeginErrorReadLine を呼び出した後で、StandardOutput ストリーム用に ReadLine を呼び出すことができます。

使用例

net view コマンドを使用して、リモート コンピュータで利用可能なネットワーク リソースを一覧表示する例を次に示します。ユーザーは対象のコンピュータ名をコマンド ライン引数として指定します。また、エラー出力のファイル名も指定できます。この例では、net コマンドの出力を収集し、プロセスの完了を待機して、出力結果をコンソールに書き込みます。ユーザーがオプションのエラー ファイルを指定した場合は、そのファイルにエラーが書き込まれます。

Visual Basic

' Define the namespaces used by this sample.
Imports System
Imports System.Text
Imports System.Globalization
Imports System.IO
Imports System.Diagnostics
Imports System.Threading
Imports System.ComponentModel
Imports Microsoft.VisualBasic


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 

C#

// 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();
                }
            }
        }
    }
} 

C++

// Define the namespaces used by this sample.
#using <System.dll>

using namespace System;
using namespace System::Text;
using namespace System::Globalization;
using namespace System::IO;
using namespace System::Diagnostics;
using namespace System::Threading;
using namespace System::ComponentModel;

ref class ProcessNetStreamRedirection
{
private:
   // Define static variables shared by class methods.
   static StreamWriter^ streamError = nullptr;
   static String^ netErrorFile = "";
   static StringBuilder^ netOutput = nullptr;
   static bool errorRedirect = false;
   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 = gcnew 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 += gcnew DataReceivedEventHandler( NetOutputDataHandler
 );
      netOutput = gcnew StringBuilder;
      if ( errorRedirect )
      {
         
         // Redirect the error output of the net command. 
         netProcess->StartInfo->RedirectStandardError = true;
         netProcess->ErrorDataReceived += gcnew 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 != nullptr )
      {
         // 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->ToString() );
      }

      if ( errorsWritten )
      {
         // Signal that the error file had something 
         // written to it.
         array<String^>^errorOutput = File::ReadAllLines( netErrorFile );
         if ( errorOutput->Length > 0 )
         {
            Console::WriteLine( "\nThe following error output was appended to
 {0}.",
               netErrorFile );
            System::Collections::IEnumerator^ myEnum = errorOutput->GetEnumerator();
            while ( myEnum->MoveNext() )
            {
               String^ errLine = safe_cast<String^>(myEnum->Current);
               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->AppendFormat(  "\n  {0}", outLine->Data );
      }
   }

   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 == nullptr )
            {
               // Open the file.
               try
               {
                  streamError = gcnew StreamWriter( netErrorFile,true
 );
               }
               catch ( Exception^ e ) 
               {
                  Console::WriteLine(  "Could not open error file!" );
                  Console::WriteLine( e->Message->ToString() );
               }
            }

            if ( streamError != nullptr )
            {
               // 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 != nullptr )
         {
            // Write redirected errors to the file.
            streamError->WriteLine( errLine->Data );
            streamError->Flush();
         }
      }
   }
};

.NET Framework のセキュリティ

• SecurityPermission  (Process のメンバを呼び出すためのアクセス許可)。要求値 : LinkDemand、名前付きアクセス許可セット、FullTrust。

プラットフォーム

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

開発プラットフォームの中には、.NET Framework によってサポートされていないバージョンがあります。サポートされているバージョンについては、「システム要件」を参照してください。

バージョン情報

.NET Framework
サポート対象 : 2.0

参照

関連項目
Process クラス
Process メンバ
System.Diagnostics 名前空間
ProcessStartInfo.RedirectStandardError
StandardError
ErrorDataReceived
DataReceivedEventHandler デリゲート
CancelErrorRead