c# - WebClient DownloadFileAsync - 如何向用户显示下载速度？

Question

这几乎就是标题中的全部问题。我有一个 WPF C# Windows 应用程序，我为用户下载文件，现在想显示速度。

Answer 1

mWebClient.DownloadProgressChanged += (sender, e) => progressChanged(e.BytesReceived);
//...
DateTime lastUpdate;
long lastBytes = 0;

private void progressChanged(long bytes)
{
    if (lastBytes == 0)
    {
        lastUpdate = DateTime.Now;
        lastBytes = bytes;
        return;
    }

    var now = DateTime.Now;
    var timeSpan = now - lastUpdate;
    var bytesChange = bytes - lastBytes;
    var bytesPerSecond = bytesChange / timeSpan.Seconds;

    lastBytes = bytes;
    lastUpdate = now;
}

然后用 bytesPerSecond 变量做任何你想做的事情。