Asp.net DownloadFileAsync与webclient问题

我正在尝试使用Webclient DownloadFileAsync方法从FTP下载文件。我使用了下面的代码

private  bool DownloadFileFromFtp()
{
    try
    {

        MyWebClient client = new MyWebClient();

        Uri ftpurl = new Uri("ftp://MyFtpserver/Filename.pdf");
        client.Credentials = new NetworkCredential("Userid", "mypassword");
        client.DownloadProgressChanged += Client_DownloadProgressChanged;

        client.DownloadDataCompleted += Client_DownloadDataCompleted;

        client.DownloadFileAsync(ftpurl, @"D:\RTP\Filename.pdf");
        return true;
    }


    catch (Exception ex)
    {
        return false;
    }
}

private void Client_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
{
    double bytesIn = double.Parse(e.BytesReceived.ToString());
    double totalBytes = double.Parse(e.TotalBytesToReceive.ToString());
    double percentage = bytesIn / totalBytes * 100;
    lbldatareceived.Text = bytesIn + "/" + totalBytes;
    lblPercentage.Text = percentage+"%";
    FileProgress.Attributes.CssStyle.Add("width", Convert.ToString(percentage) + '%');
    FileProgress.Attributes.Add("aria-valuenow", Convert.ToString(percentage));
}
private void Client_DownloadDataCompleted(object sender, DownloadDataCompletedEventArgs e)
{
    throw new NotImplementedException();
}

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当我运行此代码文件时，下载开始，浏览器开始加载。如何在不加载浏览器的情况下下载文件

请不要将C#代码标记为可以在浏览器中运行的Javascript代码。HTTP是请求/响应。当浏览器显示空进度条时，响应结束。作为服务器，您无法（使用普通HTTP）发送进一步的更新，例如应用新的CSS或属性。