FileWebRequest Klass

Definition

public ref class FileWebRequest : System::Net::WebRequest, System::Runtime::Serialization::ISerializable

public ref class FileWebRequest : System::Net::WebRequest

public class FileWebRequest : System.Net.WebRequest, System.Runtime.Serialization.ISerializable

[System.Serializable]
public class FileWebRequest : System.Net.WebRequest, System.Runtime.Serialization.ISerializable

public class FileWebRequest : System.Net.WebRequest

type FileWebRequest = class
    inherit WebRequest
    interface ISerializable

[<System.Serializable>]
type FileWebRequest = class
    inherit WebRequest
    interface ISerializable

Public Class FileWebRequest
Inherits WebRequest
Implements ISerializable

Public Class FileWebRequest
Inherits WebRequest

Arv

Object

MarshalByRefObject

WebRequest

FileWebRequest

Attribut

SerializableAttribute

Implementeringar

ISerializable

Exempel

I följande kodexempel används FileWebRequest klassen för att komma åt en filsystemresurs.

// 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 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.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

        End Class



    End Module

End Namespace

Kommentarer

Klassen FileWebRequest implementerar basklassen WebRequestabstract för URI:er (Uniform Resource Identifiers) som använder schemat file:// för att begära lokala filer.

Använd inte FileWebRequest konstruktorn. WebRequest.Create Använd metoden för att initiera nya instanser av FileWebRequest klassen. Om URI-schemat är file://Create returnerar metoden ett FileWebRequest objekt.

Metoden GetResponse gör en synkron begäran för filen som anges i RequestUri egenskapen och returnerar ett FileWebResponse objekt som innehåller svaret. Du kan göra en asynkron begäran för filen med hjälp av BeginGetResponse metoderna och EndGetResponse .

När du vill skriva data till en fil GetRequestStream returnerar metoden en Stream instans att skriva till. Metoderna BeginGetRequestStream och EndGetRequestStream ger asynkron åtkomst till skrivdataströmmen.

Klassen FileWebRequest förlitar sig på File klassen för felhantering och kodåtkomstsäkerhet.

Se även

• File