WebClient WebClient WebClient Constructor

Definition

Initialisiert eine neue Instanz der WebClient-Klasse.Initializes a new instance of the WebClient class.

public:
 WebClient();
public WebClient ();
Public Sub New ()

Beispiele

Das folgende Codebeispiel erstellt eine WebClient Instanz, und klicken Sie dann zum Herunterladen von Daten von einem Server, und klicken Sie auf der System-Konsole anzeigen, Herunterladen von Daten von einem Server und in eine Datei zu schreiben und so die Formularwerte auf einen Server hochladen und die Antwort empfangen wird.The following code example creates a WebClient instance and then uses it to download data from a server and display it on the system console, to download data from a server and write it to a file, and to upload form values to a server and receive the response.

try
{
   // Download the data to a buffer.
   WebClient^ client = gcnew WebClient;

   array<Byte>^ pageData = client->DownloadData( "http://www.contoso.com" );
   String^ pageHtml = Encoding::ASCII->GetString( pageData );
   Console::WriteLine( pageHtml );
   
   // Download the data to a file.
   client->DownloadFile( "http://www.contoso.com", "page.htm" );
   
   // Upload some form post values.
   NameValueCollection^ form = gcnew NameValueCollection;
   form->Add( "MyName", "MyValue" );
   array<Byte>^ responseData = client->UploadValues( "http://www.contoso.com/form.aspx", form );
}
catch ( WebException^ webEx ) 
{
   Console::WriteLine( webEx->ToString() );
   if ( webEx->Status == WebExceptionStatus::ConnectFailure )
   {
      Console::WriteLine( "Are you behind a firewall?  If so, go through the proxy server." );
   }
}
      try {
	
// Download the data to a buffer.
      	WebClient client = new WebClient();

		Byte[] pageData = client.DownloadData("http://www.contoso.com");
string pageHtml = Encoding.ASCII.GetString(pageData);
Console.WriteLine(pageHtml);

// Download the data to a file.
       	client.DownloadFile("http://www.contoso.com", "page.htm");

// Upload some form post values.
NameValueCollection form = new NameValueCollection();		
form.Add("MyName", "MyValue");		
Byte[] responseData = client.UploadValues("http://www.contoso.com/form.aspx", form);		

      }
      catch (WebException webEx) {
        	Console.WriteLine(webEx.ToString());
         	if(webEx.Status == WebExceptionStatus.ConnectFailure) {
         		Console.WriteLine("Are you behind a firewall?  If so, go through the proxy server.");
         	}
      }
Public Shared Sub Main()


    Try
        Dim client As New WebClient()
        Dim pageData As [Byte]() = client.DownloadData("http://www.contoso.com")
        Dim pageHtml As String = Encoding.ASCII.GetString(pageData)

        ' Download the data to a buffer.
        Console.WriteLine(pageHtml)
        
        ' Download the data to a file.
        client.DownloadFile("http://www.contoso.com", "page.htm")
        
        
        ' Upload some form post values.
        dim form as New NameValueCollection()
  form.Add("MyName", "MyValue")  

  ' Note that you need to replace "http://localhost/somefile.aspx" with the name of 
  ' a file that is available to your computer.
  Dim responseData As [Byte]() = client.UploadValues("http://www.contoso.com/form.aspx", form)      
        Console.WriteLine(Encoding.ASCII.GetString(responseData))
    
    Catch webEx As WebException
        if webEx.Status = WebExceptionStatus.ConnectFailure then
           Console.WriteLine("Are you behind a firewall?  If so, go through the proxy server.")
        end if
        Console.Write(webEx.ToString())
    End Try
    

End Sub 'Main

Hinweise

Der Standardkonstruktor erstellt eine neue Instanz der dem WebClient Klasse.The default constructor creates a new instance of the WebClient class. Die Standard-HTTP-Methode ist GET.The default HTTP method is GET. Die Standardmethode für die FTP-ist RETR.The default FTP method is RETR. Die Standardeinstellung für Encoding ist Default.The default Encoding is Default. Der Standardwert von AllowAutoRedirect ist true.The default value of AllowAutoRedirect is true.

Gilt für: