C# 5.0 Programmer's Reference

Chapter 20 ❘ 695
client.DownloadString(urlTextBox.Text);
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
3. The DownloadStringTaskAsync example program does this. The main change is to the
Download button’s Click event handler shown in the following code. Notice the async
and await keywords highlighted in bold.
// Start downloading.
async private void downloadButton_Click(object sender, EventArgs e)
{
// Get ready to give feedback.
webBrowser1.Navigate("about:blank");
downloadProgressBar.Value = 0;
downloadStatusLabel.Text = "0%";
downloadButton.Enabled = false;
cancelButton.Enabled = true;
Cursor = Cursors.WaitCursor;
// Make a Uri.
Uri uri = new Uri(urlTextBox.Text);
// Start the download.
Client = new WebClient();
Client.DownloadProgressChanged += Client_DownloadProgressChanged;
try
{
// Start the download.
string result = await Client.DownloadStringTaskAsync(uri);
// Display the result in the WebBrowser.
webBrowser1.Document.Body.InnerHtml = result;
}
catch (WebException ex)
{
if (ex.Status == WebExceptionStatus.RequestCanceled)
MessageBox.Show("Canceled");
else
MessageBox.Show(ex.Message);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
Client.Dispose();
// Remove the feedback.
downloadProgressBar.Value = 0;
downloadStatusLabel.Text = "";
downloadButton.Enabled = true;
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