FileWebRequest 类

  • 参考

定义

命名空间:
System.Net
程序集:
System.Net.Requests.dll
程序集:
System.dll
程序集:
netstandard.dll

提供 WebRequest 类的文件系统实现。

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
继承
Object
MarshalByRefObject
WebRequest
FileWebRequest
属性
SerializableAttribute
实现
ISerializable

示例

下面的代码示例使用 FileWebRequest 类访问文件系统资源。

// 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.
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

注解

类 FileWebRequest 实现 WebRequestabstract 统一资源标识符的基类， (URI) 使用 file:// 方案请求本地文件。

请勿使用 FileWebRequest 构造函数。 WebRequest.Create使用 方法初始化 类的新实例FileWebRequest。 如果 URI 方案为 file://，则 Create 该方法返回 FileWebRequest 对象。

方法 GetResponse 对 属性中指定的 RequestUri 文件发出同步请求，并返回一个 FileWebResponse 包含响应的对象。 可以使用 和 EndGetResponse 方法对文件BeginGetResponse发出异步请求。

如果要将数据写入文件，方法 GetRequestStream 将返回要 Stream 写入的实例。 BeginGetRequestStream和 EndGetRequestStream 方法提供对写入数据流的异步访问。

类 FileWebRequest 依赖于 File 类进行错误处理和代码访问安全性。

构造函数

FileWebRequest(SerializationInfo, StreamingContext)
已过时.
已过时.
已过时.

从 FileWebRequest 和 SerializationInfo 类的指定实例初始化 StreamingContext 类的新实例。

属性

AuthenticationLevel

获取或设置用于此请求的身份验证和模拟的级别。

(继承自 WebRequest)
CachePolicy

获取或设置此请求的缓存策略。

(继承自 WebRequest)
ConnectionGroupName

获取或设置请求的连接组的名称。 保留此属性供将来使用。
ContentLength

获取或设置发送的数据的内容长度。
ContentType

获取或设置发送的数据的内容类型。 保留此属性供将来使用。
CreatorInstance
已过时.

当在子类中重写时，获取从 IWebRequestCreate 类派生的工厂对象，该类用于创建为生成对指定 URI 的请求而实例化的 WebRequest。

(继承自 WebRequest)
Credentials

获取或设置与此请求关联的凭据。 保留此属性供将来使用。
Headers

获取与此请求关联的名称/值对的集合。 保留此属性供将来使用。
ImpersonationLevel

获取或设置当前请求的模拟级别。

(继承自 WebRequest)
Method

获取或设置用于请求的协议方法。 保留此属性供将来使用。
PreAuthenticate

获取或设置一个值，该值指示是否对请求进行预身份验证。 保留此属性供将来使用。
Proxy

获取或设置用于此请求的网络代理。 保留此属性供将来使用。
RequestUri

获取请求的统一资源标识符 (URI)。
Timeout

获取或设置请求超时前的时间长度。
UseDefaultCredentials

总是引发 NotSupportedException。
UseDefaultCredentials

当在子代类中重写时，获取或设置一个 Boolean 值，该值控制 DefaultCredentials 是否随请求一起发送。

(继承自 WebRequest)

方法

Abort()

取消对 Internet 资源的请求。
Abort()

中止请求。

(继承自 WebRequest)
BeginGetRequestStream(AsyncCallback, Object)

开始对用于写入数据的 Stream 对象执行异步请求。
BeginGetResponse(AsyncCallback, Object)

开始对文件系统资源的异步请求。
CreateObjRef(Type)

创建一个对象，该对象包含生成用于与远程对象进行通信的代理所需的全部相关信息。

(继承自 MarshalByRefObject)
EndGetRequestStream(IAsyncResult)

结束对 Stream 实例的异步请求，应用程序使用该实例写入数据。
EndGetResponse(IAsyncResult)

结束对文件系统资源的异步请求。
Equals(Object)

确定指定对象是否等于当前对象。

(继承自 Object)
GetHashCode()

作为默认哈希函数。

(继承自 Object)
GetLifetimeService()
已过时.

检索控制此实例的生存期策略的当前生存期服务对象。

(继承自 MarshalByRefObject)
GetObjectData(SerializationInfo, StreamingContext)
已过时.

使用将目标对象序列化所需的数据填充 SerializationInfo。
GetObjectData(SerializationInfo, StreamingContext)
已过时.

使用将目标对象序列化所需的数据填充 SerializationInfo。

(继承自 WebRequest)
GetRequestStream()

返回向文件系统资源写入数据的 Stream 对象。
GetRequestStreamAsync()

返回一个流，该流用于将数据写入文件系统资源（以异步操作形式）。
GetRequestStreamAsync()

当在子类中被重写时，将用于写入数据的 Stream 作为异步操作返回到 Internet 资源。

(继承自 WebRequest)
GetResponse()

返回对文件系统请求的响应。
GetResponseAsync()

返回对文件系统请求的响应（以异步操作形式）。
GetResponseAsync()

当在子代类中被重写时，将作为异步操作返回对 Internet 请求的响应。

(继承自 WebRequest)
GetType()

获取当前实例的 Type。

(继承自 Object)
InitializeLifetimeService()
已过时.

获取生存期服务对象来控制此实例的生存期策略。

(继承自 MarshalByRefObject)
MemberwiseClone()

创建当前 Object 的浅表副本。

(继承自 Object)
MemberwiseClone(Boolean)

创建当前 MarshalByRefObject 对象的浅表副本。

(继承自 MarshalByRefObject)
ToString()

返回表示当前对象的字符串。

(继承自 Object)

显式接口实现

ISerializable.GetObjectData(SerializationInfo, StreamingContext)
已过时.

用序列化 SerializationInfo 所需的数据来填充 FileWebRequest 对象。

适用于

另请参阅