語言

WebClient.DownloadFileCompleted 事件

定義

命名空間:
System.Net
組件:
netstandard.dll, System.Net.WebClient.dll
組件:
System.Net.WebClient.dll
組件:
System.dll
組件:
netstandard.dll
來源:
WebClient.cs
來源:
WebClient.cs
來源:
WebClient.cs
來源:
WebClient.cs
來源:
WebClient.cs

發生於異步檔案下載作業完成時。

public:
 event System::ComponentModel::AsyncCompletedEventHandler ^ DownloadFileCompleted;
public event System.ComponentModel.AsyncCompletedEventHandler? DownloadFileCompleted;
public event System.ComponentModel.AsyncCompletedEventHandler DownloadFileCompleted;
member this.DownloadFileCompleted : System.ComponentModel.AsyncCompletedEventHandler 
Public Custom Event DownloadFileCompleted As AsyncCompletedEventHandler 
Public Event DownloadFileCompleted As AsyncCompletedEventHandler

事件類型

AsyncCompletedEventHandler

範例

以下程式碼範例示範如何為事件設定事件 DownloadFileCompleted 處理程序。

// Sample call : DownLoadFileInBackground2 ("http://www.contoso.com/logs/January.txt");
void DownLoadFileInBackground2( String^ address )
{
   WebClient^ client = gcnew WebClient;
   Uri ^uri = gcnew Uri(address);

   // Call DownloadFileCallback2 when the download completes.
   client->DownloadFileCompleted += gcnew AsyncCompletedEventHandler( DownloadFileCallback2 );

   // Specify a progress notification handler here...

   client->DownloadFileAsync( uri, "serverdata.txt" );
}

void DownloadFileCallback2( Object^ /*sender*/, System::ComponentModel::AsyncCompletedEventArgs^ e )
{
   if ( e->Cancelled )
   {
      Console::WriteLine( "File download cancelled." );
   }

   if ( e->Error != nullptr )
   {
      Console::WriteLine( e->Error->ToString() );
   }
}

// 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);

    // Call DownloadFileCallback2 when the download completes.
    client.DownloadFileCompleted += new AsyncCompletedEventHandler(DownloadFileCallback2);

    // Specify a progress notification handler here ...

    client.DownloadFileAsync(uri, "serverdata.txt");
}

private static void DownloadFileCallback2(object sender, AsyncCompletedEventArgs e)
{
    if (e.Cancelled)
    {
        Console.WriteLine("File download cancelled.");
    }

    if (e.Error != null)
    {
        Console.WriteLine(e.Error.ToString());
    }
}

' Sample call : DownLoadFileInBackground2 ("http:' www.contoso.com/logs/January.txt")
Public Shared Sub DownLoadFileInBackground2(address As String)

    Dim client As WebClient = New WebClient()

    ' Call DownloadFileCallback2 when the download completes.
    AddHandler client.DownloadFileCompleted, AddressOf DownloadFileCallback2

    ' Specify a progress notification handler here...

    Dim uri as Uri = New Uri(address)
    client.DownloadFileAsync(uri, "serverdata.txt")
End Sub

Private Shared Sub DownloadFileCallback2(sender As Object, e As AsyncCompletedEventArgs)
    If e.Cancelled = True Then
        Console.WriteLine("File download cancelled.")
    End If

    If Not e.Error Is Nothing Then
        Console.WriteLine(e.Error.ToString())
    End If
End Sub

備註

注意事項

WebRequest、、HttpWebRequest、ServicePointWebClient、和 都已過時，你不應該用它們來做新開發。 請改用 HttpClient。

每當非同步檔案下載操作完成時，此事件都會被觸發。 非同步檔案下載是透過呼叫這些 DownloadFileAsync 方法開始的。

這是 AsyncCompletedEventHandler 本次活動的代表。 該 AsyncCompletedEventArgs 類別提供事件處理程序事件資料。

欲了解更多如何處理事件的資訊，請參閱 「處理與提升事件」。

適用於