使用 C# 的下载器的下载速率

Question

我想在我的下载器中实现下载速率。谷歌搜索后发现一个相当复杂的应用程序Download manager - limit download speed。然后，在另一个线程https://stackoverflow.com/questions/26073779/how-to-add-download-rate-and-limit-rate-in-downloader-in-c-sharp 上找到了一个很好的建议：

设置一个每秒触发一次的计时器，并使用计数器记录已下载的字节数，在计时器 Tick 事件中将下载速率报告为 x Bytes/s，并将计数器重置为零

刚刚开始实现这个，使用

bytesIn = int.Parse(e.BytesReceived.ToString());
totalBytes = int.Parse(e.TotalBytesToReceive.ToString());

我的代码中有 bytesIn 显示已接收字节数，但如何使用计时器实现上面引用的建议，就好像我使用 tick() 事件并在每个 tick() 事件上计数它不会显示我的失败-速度。

请给点建议？

Answer 1

您需要做的是在计时器期间记录bytesIn 并将其存储起来以备后用。下次计时器触发时（一秒后），您获取新的bytesIn 值，然后减去之前的值。这将为您提供最后一秒下载的字节数。您可以在屏幕上将此数字显示为#### Bytes/s，也可以将该数字除以1024，然后将结果显示为#### Kbytes/s。

long lastDownload = 0;
long bytesIn = 0

//This is a event for a timer that fires once per second on the UI thread.
private void TimerTick(object sender, EventArgs e)
{
     //Figure out how many bytes where downloaded in the last second.
     var bytesDownloadedLastSecond = bytesIn - lastsDownload;

     //Copy the number over for the next firing of TimerTick.
     lastDownload = bytesIn;


     double scalingFactor;    
     string formatText;

     //Figure out if we should display in bytes, kilobytes or megabytes per second.
     if(bytesDownloadedLastSecond < 1024)
     {
          formatText = "{0:N0} B/sec";
          scalingFactor = 1;
     }
     else if(bytesDownloadedLastSecond < 1024 * 1024)
     {
          formatText = "{0:N2} Kb/sec";
          scalingFactor = 1024;
     }
     else
     {
          formatText = "{0:N2} Mb/sec";
          scalingFactor = 1024 * 1024;
     }

     //Display the speed to the user, scaled to the correct size.
     speedTextBox.Text = String.Format(formatText, bytesDownloadedLastSecond / scalingFactor );
}

private void DownloadProgress(object sender, EventArgs e)
{
    bytesIn = int.Parse(e.BytesReceived.ToString());
    totalBytes = int.Parse(e.TotalBytesToReceive.ToString());
}