FileWebRequest-Klasse
Stellt eine Dateisystemimplementierung der WebRequest-Klasse bereit.
Namespace: System.Net
Assembly: System (in system.dll)
Syntax
'Declaration
<SerializableAttribute> _
Public Class FileWebRequest
Inherits WebRequest
Implements ISerializable
'Usage
Dim instance As FileWebRequest
[SerializableAttribute]
public class FileWebRequest : WebRequest, ISerializable
[SerializableAttribute]
public ref class FileWebRequest : public WebRequest, ISerializable
/** @attribute SerializableAttribute() */
public class FileWebRequest extends WebRequest implements ISerializable
SerializableAttribute
public class FileWebRequest extends WebRequest implements ISerializable
Hinweise
Die FileWebRequest-Klasse implementiert die WebRequestabstract-Basisklasse für URIs (Uniform Resource Identifier), die zum Anfordern von lokalen Dateien das file://-Schema verwenden.
Verwenden Sie nicht den FileWebRequest-Konstruktor. Verwenden Sie die WebRequest.Create-Methode, um neue Instanzen der FileWebRequest-Klasse zu initialisieren. Wenn das URI-Schema file:// ist, gibt die Create-Methode ein FileWebRequest-Objekt zurück.
Die GetResponse-Methode führt eine synchrone Anforderung für die in der RequestUri-Eigenschaft angegebene Datei aus und gibt ein FileWebResponse-Objekt mit der Antwort zurück. Mithilfe der BeginGetResponse-Methode und der EndGetResponse-Methode können Sie eine asynchrone Anforderung der Datei ausführen.
Wenn Sie Daten in eine Datei schreiben möchten, gibt die GetRequestStream-Methode eine Stream-Instanz zurück, in die geschrieben werden kann. Die BeginGetRequestStream-Methode und die EndGetRequestStream-Methode ermöglichen den asynchronen Zugriff auf den Schreibdatenstream.
Die FileWebRequest-Klasse ist im Hinblick auf die Fehlerbehandlung und Codezugriffssicherheit auf die File-Klasse angewiesen.
Beispiel
Im folgenden Codebeispiel wird die FileWebRequest-Klasse verwendet, um auf eine Dateisystemressource zuzugreifen.
'
' 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 ();
}
}
}
}
// 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
Vererbungshierarchie
System.Object
System.MarshalByRefObject
System.Net.WebRequest
System.Net.FileWebRequest
Threadsicherheit
Alle öffentlichen statischen (Shared in Visual Basic) Member dieses Typs sind threadsicher. Bei Instanzmembern ist die Threadsicherheit nicht gewährleistet.
Plattformen
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
.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.
Versionsinformationen
.NET Framework
Unterstützt in: 2.0, 1.1, 1.0