Comment : envoyer une demande HTTP avec un proxy

Mise à jour : novembre 2007

Le .NET Compact Framework prend en charge des services Web. Cet exemple envoie une requête HTTP GET avec ou sans proxy spécifié.

Exemple

Dans l'exemple de code suivant, un clic de bouton envoie la requête et traite la réponse. La requête utilise un proxy uniquement s'il est spécifié et utilise la classe WebException pour gérer toutes les exceptions. Elle utilise un StreamReader pour lire la réponse HTML dans un tableau de caractères mis en mémoire tampon.

Private ReceiveStream As System.IO.Stream
Private sr As System.IO.StreamReader

Private Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click

    ' Get URL and proxy
    ' from the text boxes.
    Dim url As String = txtURL.Text
    Dim proxy As String = txtProxy.Text

    Try
        If Not "".Equals(txtProxy.Text) Then
            Dim proxyObject As New WebProxy(proxy, 80)

            ' Disable proxy use when the host is local.
            proxyObject.BypassProxyOnLocal = True

            ' HTTP requests use this proxy information.
            GlobalProxySelection.Select = proxyObject
        End If

        Dim req As WebRequest = WebRequest.Create(url)
        Dim result As WebResponse = req.GetResponse()
        ReceiveStream = result.GetResponseStream()
        Dim encode As Encoding = System.Text.Encoding.GetEncoding("utf-8")
        sr = New StreamReader(ReceiveStream, encode)

        ' Read the stream into arrays of 30 characters
        ' to add as items in the list box. Repeat until
        ' buffer is read.
        Dim read(29) As [Char]
        Dim count As Integer = sr.Read(read, 0, 30)
        While count > 0
            Dim str As New String(read, 0, count)
            lstResults.Items.Add(str)
            count = sr.Read(read, 0, 30)
        End While
    Catch ex As WebException
        Dim message As String = ex.Message
        Dim response As HttpWebResponse = CType(ex.Response, HttpWebResponse)
        If Nothing Is response Then
        Else
            message = response.StatusDescription
            response.Close()
        End If
        lstResults.Items.Add(message)
    Catch ex As Exception
        lstResults.Items.Add(ex.Message)
    Finally
        ReceiveStream.Close()
        sr.Close()
    End Try
End Sub

Stream ReceiveStream = null;
StreamReader sr = null;

private void button1_Click(object sender, System.EventArgs e)
{

    // Get URL and proxy
    // from the text boxes.
    string url = txtURL.Text;
    string proxy = txtProxy.Text;

    try 
    {
        if(!"".Equals(txtProxy.Text))
        {
            WebProxy proxyObject = new WebProxy(proxy, 80);

            // Disable proxy use when the host is local.
            proxyObject.BypassProxyOnLocal = true;

            // HTTP requests use this proxy information.
            GlobalProxySelection.Select = proxyObject;

        }

        WebRequest req = WebRequest.Create(url);
        WebResponse result = req.GetResponse();
        ReceiveStream = result.GetResponseStream();
        Encoding encode = System.Text.Encoding.GetEncoding("utf-8");
        sr = new StreamReader( ReceiveStream, encode );

        // Read the stream into arrays of 30 characters
        // to add as items in the list box. Repeat until
        // buffer is read.
        Char[] read = new Char[30];
        int count = sr.Read( read, 0, 30 );
        while (count > 0) 
        {
            String str = new String(read, 0, count);
            lstResults.Items.Add(str);
            count = sr.Read(read, 0, 30);
        }
    } 
    catch(WebException ex)
    {
       string message = ex.Message;
       HttpWebResponse response = (HttpWebResponse)ex.Response;
       if(null != response)
       {
           message = response.StatusDescription;
           response.Close();
       }
       lstResults.Items.Add(message);              
    }
    catch(Exception ex) 
    {
        lstResults.Items.Add(ex.Message);
    }
    finally
    {
        ReceiveStream.Close();
        sr.Close();
    }

}

Compilation du code

Cet exemple nécessite des références aux espaces de noms suivants :

• System

• System.Net

• System.Text

• System.IO

• System.Windows.Forms

Voir aussi

Autres ressources

Mise en réseau et connectivité dans le .NET Compact Framework