WebClient Constructor

public:
 WebClient();

public WebClient();

Public Sub New ()

Voorbeelden

In het volgende codevoorbeeld wordt een WebClient exemplaar gemaakt en vervolgens gebruikt om gegevens van een server te downloaden en weer te geven op de systeemconsole, om gegevens van een server te downloaden en naar een bestand te schrijven en formulierwaarden naar een server te uploaden en het antwoord te ontvangen.

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

Opmerkingen

De parameterloze constructor maakt een nieuw exemplaar van de WebClient klasse. De standaard-HTTP-methode is GET. De standaard FTP-methode is RETR. De standaardwaarde Encoding is Default. De standaardwaarde van AllowAutoRedirect is true.