FileWebRequest クラスとは何？わかりやすく解説 Weblio辞書

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.NET Framework クラスライブラリリファレンス

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FileWebRequest クラス

WebRequest クラスのファイルシステムの実装を提供します。

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

Visual Basic (宣言)

<SerializableAttribute> _
Public Class FileWebRequest
    Inherits WebRequest
    Implements ISerializable

Visual Basic (使用法)

Dim instance As FileWebRequest

[SerializableAttribute] 
public class FileWebRequest : WebRequest, ISerializable

C++

[SerializableAttribute] 
public ref class FileWebRequest : public
 WebRequest, ISerializable

/** @attribute SerializableAttribute() */ 
public class FileWebRequest extends WebRequest
 implements ISerializable

JScript

SerializableAttribute 
public class FileWebRequest extends
 WebRequest implements ISerializable

解説

FileWebRequest クラスは、file:// スキームを使用してローカルファイルを要求する URI (Uniform Resource Identifier) に対して WebRequestabstract 基本クラスを実装します。

FileWebRequest コンストラクタは使用しないでください。FileWebRequest クラスの新しいインスタンスを初期化するには、WebRequest.Create メソッドを使用します。URI スキームが file:// である場合、Create メソッドは、FileWebRequest オブジェクトを返します。

GetResponse メソッドは、RequestUri プロパティで指定されるファイルへの同期要求を行い、応答を格納した FileWebResponse オブジェクトを返します。BeginGetResponse メソッドと EndGetResponse メソッドを使用して、ファイルへの非同期要求を可能にします。

ファイルにデータを書き込む場合、GetRequestStream メソッドは書き込み先の Stream インスタンスを返します。BeginGetRequestStream メソッドと EndGetRequestStream メソッドは、書き込みデータストリームへの非同期アクセスを可能にします。

FileWebRequest クラスは、エラー処理とコードアクセスセキュリティのために File クラスを使用します。

使用例

FileWebRequest クラスを使用してファイルシステムリソースにアクセスするコード例を次に示します。

Visual Basic

'
' This example creates or opens a text file and stores a string in it.
 
' Both the file and the string are passed by the user.
' Note. For this program to work, the folder containing the test file
' must be shared, with its permissions set to allow write access. 

Imports System.Net
Imports System
Imports System.IO
Imports System.Text

Namespace Mssc.PluggableProtocols.File

    Module TestGetRequestStream

        Class TestGetRequestStream

            Private Shared myFileWebRequest
 As FileWebRequest

            ' Show how to use this program.
            Private Shared Sub
 showUsage()
                Console.WriteLine(ControlChars.Lf + "Please enter
 file name and timeout :")
                Console.WriteLine("Usage: vb_getrequeststream
 <systemname>/<sharedfoldername>/<filename> timeout")
                Console.WriteLine("Example: vb_getrequeststream
 ngetrequestrtream() ndpue/temp/hello.txt  1000")
                Console.WriteLine("Small time-out values (for
 example, 3 or less) cause a time-out exception.")
            End Sub

            Private Shared Sub
 makeFileRequest(ByVal fileName As String,
 ByVal timeout As Integer)
                Try
                    ' Create a Uri object.to access the file requested
 by the user. 
                    Dim myUrl As New
 Uri("file://" + fileName)

                    ' Create a FileWebRequest object.for the requeste
 file.
                    myFileWebRequest = CType(WebRequest.CreateDefault(myUrl), FileWebRequest)

                    ' Set the time-out to the value selected by the
 user.
                    myFileWebRequest.Timeout = timeout

                    ' Set the Method property to POST  
                    myFileWebRequest.Method = "POST"


                Catch e As WebException
                    Console.WriteLine(("WebException is: "
 + e.Message))
                Catch e As UriFormatException
                    Console.WriteLine(("UriFormatWebException
 is: " + e.Message))
                End Try

            End Sub

            Private Shared Sub
 writeToFile()
                Try
                    ' Enter the string to write to the file.
                    Console.WriteLine("Enter the string you want
 to write:")
                    Dim userInput As String
 = Console.ReadLine()

                    ' Convert the string to a byte array.
                    Dim encoder As New
 ASCIIEncoding
                    Dim byteArray As Byte()
 = encoder.GetBytes(userInput)

                    ' Set the ContentLength property.
                    myFileWebRequest.ContentLength = byteArray.Length

                    Dim contentLength As String
 = myFileWebRequest.ContentLength.ToString()

                    Console.WriteLine(ControlChars.Lf + "The content
 length is {0}.", contentLength)


                    ' Get the file stream handler to write to the file.
                    Dim readStream As Stream
 = myFileWebRequest.GetRequestStream()

                    ' Write to the stream. 
                    ' Note. For this to work the file must be accessible
                    ' on the network. This can be accomplished by setting
 the property
                    ' sharing of the folder containg the file.  
                    ' FileWebRequest.Credentials property cannot be
 used for this purpose.
                    readStream.Write(byteArray, 0, userInput.Length)


                    Console.WriteLine(ControlChars.Lf + "The String
 you entered was successfully written to the file.")

                    readStream.Close()

                Catch e As WebException
                    Console.WriteLine(("WebException is: "
 + e.Message))
                Catch e As UriFormatException
                    Console.WriteLine(("UriFormatWebException
 is: " + e.Message))
                End Try

            End Sub

            Public Shared Sub
 Main(ByVal args() As String)

                If args.Length < 2 Then
                    showUsage()
                Else
                    makeFileRequest(args(0), Integer.Parse(args(1)))
                    writeToFile()
                End If

            End Sub 'Main

        End Class 'TestGetRequestStream



    End Module

End Namespace

// This example creates or opens a text file and stores a string in
 it. 
// Both the file and the string are passed by the user.
// Note. For this program to work, the folder containing the test file
// must be shared, with its permissions set to allow write access. 
using System.Net;
using System;
using System.IO;
using System.Text;

namespace Mssc.PluggableProtocols.File
{
    class TestGetRequestStream
    {
        private static FileWebRequest myFileWebRequest;

        private static void
 showUsage ()
        {
            Console.WriteLine ("\nPlease enter file name and timeout :");
            Console.WriteLine ("Usage: cs_getrequeststream <systemname>/<sharedfoldername>/<filename>
 timeout");
            Console.WriteLine ("Example: cs_getrequeststream ngetrequestrtream()
 ndpue/temp/hello.txt  1000");
            Console.WriteLine ("Small time-out values (for
 example, 3 or less) cause a time-out exception.");
        }

        private static void
 makeFileRequest (string fileName, int timeout)
        {
            try
            {
                // Create a Uri object. 
                Uri myUrl = new Uri ("file://"
 + fileName);

                // Create a FileWebRequest object.
                myFileWebRequest = (FileWebRequest)WebRequest.CreateDefault (myUrl);

                // Set the time-out to the value selected by the user.
                myFileWebRequest.Timeout = timeout;

                // Set the Method property to POST  
                myFileWebRequest.Method = "POST";
            }
            catch (WebException e)
            {
                Console.WriteLine ("WebException: " + e.Message);
            }
            catch (UriFormatException e)
            {
                Console.WriteLine ("UriFormatWebException: " + e.Message);
            }
        }

        private static void
 writeToFile ()
        {
            try
            {
                // Enter the string to write to the file.
                Console.WriteLine ("Enter the string you
 want to write:");

                string userInput = Console.ReadLine ();

                // Convert the string to a byte array.
                ASCIIEncoding encoder = new ASCIIEncoding ();
                byte[] byteArray = encoder.GetBytes (userInput);

                // Set the ContentLength property.
                myFileWebRequest.ContentLength = byteArray.Length;

                string contentLength = myFileWebRequest.ContentLength.ToString
 ();

                Console.WriteLine ("\nThe content length is {0}.", contentLength);

                // Get the file stream handler to write to the file.
                Stream readStream = myFileWebRequest.GetRequestStream ();

                // Write to the file stream. 
                // Note.  For this to work, the file must be accessible
                // on the network. This can be accomplished by setting
 the property
                // sharing of the folder containg the file. 
                // FileWebRequest.Credentials property cannot be used
 for this purpose.
                readStream.Write (byteArray, 0, userInput.Length);
                Console.WriteLine ("\nThe String you entered was successfully
 written to the file.");

                readStream.Close ();
            }
            catch (WebException e)
            {
                Console.WriteLine ("The WebException: " + e.Message);
            }
            catch (UriFormatException e)
            {
                Console.WriteLine ("The UriFormatWebException: " + e.Message);
            }
        }

        public static void
 Main (String[] args)
        {
            if (args.Length < 2)
                showUsage ();
            else
            {
                makeFileRequest (args[0], int.Parse (args[1]));
                writeToFile ();
            }
        }
    }
}

C++

// This program creates or open a text file in which it stores a string.
// Both file and string are passed by the user.
// Note. In order for this program to work, the folder containing the
 test file
// must be shared with its permissions set to allow write access.
#using <System.dll>

using namespace System;
using namespace System::IO;
using namespace System::Text;
using namespace System::Net;
ref class TestGetRequestStream
{
private:
   static FileWebRequest^ myFileWebRequest;
   static void showUsage()
   {
      Console::WriteLine( "\nPlease enter file name and timeout :" );
      Console::WriteLine( "Usage: cs_getrequeststream <systemname>/<sharedfoldername>/<filename>
 timeout" );
      Console::WriteLine( "Example: cs_getrequeststream ndpue/temp/hello.txt
 1000" );
      Console::WriteLine( "Small timeout values (for instance
 3 or less) cause a timeout exception." );
   }

   static void makeFileRequest( String^ fileName,
 int timeout )
   {
      try
      {
         
         // Create a Uri object.
         Uri^ myUrl = gcnew Uri( String::Format( "file://{0}",
 fileName ) );
         
         // Create a FileWebRequest object.
         myFileWebRequest = dynamic_cast<FileWebRequest^>(WebRequest::CreateDefault(
 myUrl ));
         
         // Set the timeout to the value selected by the user.
         myFileWebRequest->Timeout = timeout;
         
         // Set the Method property to POST
         myFileWebRequest->Method = "POST";
         
      }
      catch ( WebException^ e ) 
      {
         Console::WriteLine( "WebException: {0}", e->Message );
      }
      catch ( UriFormatException^ e ) 
      {
         Console::WriteLine( "UriFormatWebException: {0}", e->Message
 );
      }

   }

   static void writeToFile()
   {
      try
      {
         
         // Enter the string to write into the file.
         Console::WriteLine( "Enter the string you want to
 write:" );
         String^ userInput = Console::ReadLine();
         
         // Convert the string to Byte array.
         ASCIIEncoding^ encoder = gcnew ASCIIEncoding;
         array<Byte>^byteArray = encoder->GetBytes( userInput );
         
         // Set the ContentLength property.
         myFileWebRequest->ContentLength = byteArray->Length;
         String^ contentLength = myFileWebRequest->ContentLength.ToString();
         Console::WriteLine( "\nThe content length is {0}.", contentLength
 );
         
         // Get the file stream handler to write into the file.
         Stream^ readStream = myFileWebRequest->GetRequestStream();
         
         // Write to the file stream.
         // Note. In order for this to work the file must be accessible
         // on the network. This can be accomplished by setting the
 property
         // sharing of the folder containg the file. The permissions
         // can be set so everyone can modify the file.
         // FileWebRequest::Credentials property cannot be used for
 this purpose.
         readStream->Write( byteArray, 0, userInput->Length );
         Console::WriteLine( "\nThe String you entered was successfully written
 into the file." );
         
         readStream->Close();
      }
      catch ( WebException^ e ) 
      {
         Console::WriteLine( "The WebException: {0}", e->Message );
      }
      catch ( UriFormatException^ e ) 
      {
         Console::WriteLine( "The UriFormatWebException: {0}", e->Message
 );
      }

   }


public:
   static void Main()
   {
      array<String^>^args = Environment::GetCommandLineArgs();
      if ( args->Length < 3 )
            showUsage();
      else
      {
         makeFileRequest( args[ 1 ], Int32::Parse( args[ 2 ] ) );
         writeToFile();
      }
   }

};

int main()
{
   TestGetRequestStream::Main();
}

// This example creates or opens a text file and stores a string in
 it. 
// Both the file and the string are passed by the user.
// Note. For this program to work, the folder containing the test file
// must be shared, with its permissions set to allow write access. 
import System.Net.*;
import System.*;
import System.IO.*;
import System.Text.*;

class TestGetRequestStream
{
    private static FileWebRequest myFileWebRequest;

    private static void
 ShowUsage()
    {
        Console.WriteLine("\nPlease enter file name and timeout :");
        Console.WriteLine("Usage: jsl_getrequeststream <systemname>/"
 
            + "<sharedfoldername>/<filename> timeout");
        Console.WriteLine("Example: cs_getrequeststream ngetrequestrtream()"
 
            + "ndpue/temp/hello.txt  1000");
        Console.WriteLine("Small time-out values (for example,
 3 or less) " 
            + "cause a time-out exception.");
    } //ShowUsage

    private static void
 MakeFileRequest(String fileName, int timeout)
    {
        try {
            // Create a Uri object. 
            Uri myUrl = new Uri("file://"
 + fileName);

            // Create a FileWebRequest object.
            myFileWebRequest = 
                ((FileWebRequest)(WebRequest.CreateDefault(myUrl)));

            // Set the time-out to the value selected by the user.
            myFileWebRequest.set_Timeout(timeout);
            // Set the Method property to POST  
            myFileWebRequest.set_Method("POST");
        }
        catch (WebException e) {
            Console.WriteLine(("WebException: " + e.get_Message()));
        }
        catch (UriFormatException e) {
            Console.WriteLine(("UriFormatWebException: " + e.get_Message()));
        }
    } //MakeFileRequest

    private static void
 WriteToFile()
    {
        try {
            // Enter the string to write to the file.
            Console.WriteLine("Enter the string you want
 to write:");
            String userInput = Console.ReadLine();

            // Convert the string to a byte array.
            ASCIIEncoding encoder = new ASCIIEncoding();
            ubyte byteArray[] = encoder.GetBytes(userInput);

            // Set the ContentLength property.
            myFileWebRequest.set_ContentLength(byteArray.length);
            String contentLength = 
                (new Long(myFileWebRequest.get_ContentLength())).ToString();
            Console.WriteLine("\nThe content length is {0}.", contentLength);

            // Get the file stream handler to write to the file.
            Stream readStream = myFileWebRequest.GetRequestStream();

            // Write to the file stream. 
            // Note.  For this to work, the file must be accessible
            // on the network. This can be accomplished by setting the
 property
            // sharing of the folder containg the file. 
            // FileWebRequest.Credentials property cannot be used for
 
            // this purpose.
            readStream.Write(byteArray, 0, userInput.get_Length());
            Console.WriteLine("\nThe String you entered was successfully "
 
                + "written to the file.");
            readStream.Close();
        }
        catch (WebException e) {
            Console.WriteLine(("The WebException: " + e.get_Message()));
        }
        catch (UriFormatException e) {
            Console.WriteLine(("The UriFormatWebException: " 
                + e.get_Message()));
        }
    } //WriteToFile

    public static void main(String[]
 args)
    {
        if (args.length < 2) {
            ShowUsage();
        }
        else {
            MakeFileRequest(args[0], Integer.parseInt(args[1]));
            WriteToFile();
        }
    } //main
} //TestGetRequestStream

継承階層

System.Object
   System.MarshalByRefObject
     System.Net.WebRequest
      System.Net.FileWebRequest

スレッドセーフ

この型の public static (Visual Basic では Shared) メンバはすべて、スレッドセーフです。インスタンスメンバの場合は、スレッドセーフであるとは限りません。

プラットフォーム

バージョン情報

.NET Framework
サポート対象 : 2.0、1.1、1.0

参照

関連項目
FileWebRequest メンバ
System.Net 名前空間
File

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FileWebRequest クラスとは？わかりやすく解説