System.Net.WebClient class for GET

I got a small application to download file .

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Net;
namespace Microsoft.Samples.WebClientProgress
{
///

/// WebClientProgress demonstrates how to download a file with a progress
/// indicator without blocking any of the user interface.
///

public partial class WebClientProgressForm : System.Windows.Forms.Form
{
private bool isBusy;
private WebClient client;
public WebClientProgressForm()
{
InitializeComponent();
client = new WebClient();
// Wire up the download complete event handler.
// The operation will either complete successfully or with an
// error code.
client.DownloadFileCompleted += client_DownloadFileCompleted;
// Wire up the download progress event handler.
client.DownloadProgressChanged += client_DownloadProgressChanged;
}
private void btnDownload_Click(object sender, System.EventArgs e)
{
// If an operation is pending, then the user has clicked cancel.
if (isBusy)
{
client.CancelAsync();
isBusy = false;
this.downloadButton.Text = "Download";
}
// Otherwise go ahead and start the download
else
{
try {
Uri uri = new Uri(urlTextBox.Text);
this.downloadProgressBar.Value = 0;
client.DownloadFileAsync(uri, "localfile.htm");
this.downloadButton.Text = "Cancel";
isBusy = true;
}
catch (UriFormatException ex) {
MessageBox.Show(ex.Message);
}
}
}
// Displays a message indicating that the download completed
// successfully, or if there was an error it will be displayed instead.
private void client_DownloadFileCompleted(
object sender, AsyncCompletedEventArgs e)
{
isBusy = false;
this.downloadButton.Text = "Download";
if (e.Error == null)
MessageBox.Show("Download Complete");
else
MessageBox.Show("Download Not Complete: " + e.Error.Message);
}
// Updates the progress indicator with the latest progress
private void client_DownloadProgressChanged(
object sender, DownloadProgressChangedEventArgs e)
{
this.downloadProgressBar.Value = e.ProgressPercentage;
}
}
}