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FileWebRequest Class

Provides a file system implementation of the WebRequest class.

For a list of all members of this type, see FileWebRequest Members.

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

[Visual Basic]
<Serializable>
Public Class FileWebRequest
   Inherits WebRequest
[C#]
[Serializable]
public class FileWebRequest : WebRequest
[C++]
[Serializable]
public __gc class FileWebRequest : public WebRequest
[JScript]
public
   Serializable
class FileWebRequest extends WebRequest

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Remarks

The FileWebRequest class implements the WebRequest abstract (MustInherit in Visual Basic) base class for URIs that use the file:// scheme to request local files.

Do not use the FileWebRequest constructor. Use the WebRequest.Create method to initialize new instances of the FileWebRequest class. If the URI scheme is file://, the Create method returns a FileWebRequest instance.

The GetResponse method makes a synchronous request for the file specified in the RequestUri property and returns a FileWebResponse instance containing the response. You can make an asynchronous request for the file using the BeginGetResponse and EndGetResponse methods.

When you want to write data to a file, the GetRequestStream method returns a Stream instance to write to. The BeginGetRequestStream and EndGetRequestStream methods provide asynchronous access to the write data stream.

The FileWebRequest class relies on the File class for error handling and code access security.

Example

[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


[C#] 

// 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 <mscorlib.dll>
#using <System.dll>

using namespace System;
using namespace System::IO;
using namespace System::Text;
using namespace System::Net;

__gc class TestGetRequestStream {
private:
   static FileWebRequest*  myFileWebRequest;

   static void showUsage() {
      Console::WriteLine(S"\nPlease enter file name and timeout :");

      Console::WriteLine(S"Usage: cs_getrequeststream <systemname>/<sharedfoldername>/<filename> timeout");
      Console::WriteLine(S"Example: cs_getrequeststream ndpue/temp/hello.txt 1000");
      Console::WriteLine(S"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 = new Uri(String::Format(S"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=S"POST";
      } catch (WebException* e) {
         Console::WriteLine(S"WebException: {0}", e->Message);
      } catch (UriFormatException* e) {
         Console::WriteLine(S"UriFormatWebException: {0}", e->Message);
      }
   }

   static void writeToFile() {
      try {
         // Enter the string to write into the file.
         Console::WriteLine(S"Enter the string you want to write:");
         String* userInput = Console::ReadLine();
         // Convert the string to 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(S"\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(S"\nThe String you entered was successfully written into the file.");

         readStream->Close();

      } catch (WebException* e) {
         Console::WriteLine(S"The WebException: {0}", e->Message);
      } catch (UriFormatException* e) {
         Console::WriteLine(S"The UriFormatWebException: {0}", e->Message);
      }
   }

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

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

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Namespace: System.Net

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

Assembly: System (in System.dll)

See Also

FileWebRequest Members | System.Net Namespace | File

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