WebClient.DownloadProgressChanged Event
Occurs when an asynchronous download operation successfully transfers some or all of the data.
Namespace: System.Net
Assembly: System (in System.dll)
This event is raised each time an asynchronous download makes progress. This event is raised when downloads are started using any of the following methods.
Method | Description |
|---|---|
Downloads data from a resource and returns a Byte array, without blocking the calling thread. | |
Downloads data from a resource to a local file, without blocking the calling thread. | |
Returns the data from a resource, without blocking the calling thread. |
The DownloadProgressChangedEventHandler is the delegate for this event. The DownloadProgressChangedEventArgs class provides the event handler with event data.
For more information about handling events, see Consuming Events.
 Note |
|---|
A passive FTP file transfer will always show a progress percentage of zero, since the server did not send the file size. To show progress, you can change the FTP connection to active by overriding the GetWebRequest virtual method: |
internal class MyWebClient:WebClient{
protected override WebRequest GetWebRequest(Uri address) {
FtpWebRequest req = (FtpWebRequest)base.GetWebRequest(address);
req.UsePassive = false;
return req;
}
}
The following code example demonstrates setting an event handler for this event.
// Sample call : DownLoadFileInBackground2 ("http://www.contoso.com/logs/January.txt");
public static void DownLoadFileInBackground2 (string address)
{
WebClient client = new WebClient ();
Uri uri = new Uri(address);
// Specify that the DownloadFileCallback method gets called
// when the download completes.
client.DownloadFileCompleted += new AsyncCompletedEventHandler (DownloadFileCallback2);
// Specify a progress notification handler.
client.DownloadProgressChanged += new DownloadProgressChangedEventHandler(DownloadProgressCallback);
client.DownloadFileAsync (uri, "serverdata.txt");
}
The following code example shows an implementation of a handler for this event.
private static void UploadProgressCallback(object sender, UploadProgressChangedEventArgs e) { // Displays the operation identifier, and the transfer progress. Console.WriteLine("{0} uploaded {1} of {2} bytes. {3} % complete...", (string)e.UserState, e.BytesSent, e.TotalBytesToSend, e.ProgressPercentage); } private static void DownloadProgressCallback(object sender, DownloadProgressChangedEventArgs e) { // Displays the operation identifier, and the transfer progress. Console.WriteLine("{0} downloaded {1} of {2} bytes. {3} % complete...", (string)e.UserState, e.BytesReceived, e.TotalBytesToReceive, e.ProgressPercentage); }
Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
