Question

我正在制作一个下载大量文件的简单程序。现在我想向用户显示“xx剩余时间”（就像你用uTorrent看到的那样）。

到目前为止这是我得到的

正在下载文件

// Download the file
//Console.WriteLine("Downloading \"{0}\" from {1}...", node.Name, Config.FTP_HOST + "/" + node.DirectoryFileIsIn);
FtpWebRequest request = CreateRequest("ftp://" + Config.FTP_HOST + "/" + node.DirectoryFileIsIn + "/" + node.Name, WebRequestMethods.Ftp.DownloadFile.ToString());
FtpWebResponse response = (FtpWebResponse)request.GetResponse();
Stream responseStream = response.GetResponseStream();
FileStream filestream = new FileStream(new_path, FileMode.Create);

int chunkSize = 1024;
long total = node.FileSize;
int streamPosition = 0;
while (true)
{
    byte[] buffer = new byte[Math.Min(chunkSize, node.FileSize - streamPosition)];
    //byte[] buffer = new byte[chunkSize];
    int readBytes = responseStream.Read(buffer, 0, buffer.Length);

    if (readBytes == 0)
        break;

    currentFileSizeDownloaded += readBytes; // total bytes downloaded
    bytesSnapshot += readBytes; // for tracking download speed
    streamPosition += readBytes; // for tracking response stream position

    filestream.Write(buffer, 0, readBytes);
}

filestream.Flush();
//Console.WriteLine("Download Complete, status {0}", response.StatusDescription);

response.Dispose();
filestream.Dispose();

response.Close();
filestream.Close();

捕获下载的字节数（单独的线程）

// Calculate total download time
public static void CalculateDownloadTime()
{
    bytesSnapshot = 0;
    int waitTime = 10000;
    Thread.Sleep(waitTime); // sleep 10 seconds

    if (bytesSnapshot > 0)
    {
        double downloadSpeed = (bytesSnapshot / 10); // bytes per second
        long remainingTime = (totalFileSizeToDownload - currentFileSizeDownloaded) / (long)downloadSpeed;
        Console.WriteLine("Download speed {0}", Formatting.FormatBytes((long)downloadSpeed));
        Console.WriteLine("Remaining time {0}", Formatting.FormatSeconds(remainingTime));
        Console.WriteLine();
    }
    else
    {
        Console.WriteLine("byteSnapshot = 0"); // DEBUG
        downloadTracker.Abort();
        return;
    }

    CalculateDownloadTime();
}

输出

Download speed 106,73 KB
Remaining time 0:01:52

Download speed 9,02 KB
Remaining time 0:22:05

Download speed 8,94 KB
Remaining time 0:22:06

Download speed 7,68 KB
Remaining time 0:25:35

Download speed 7,68 KB
Remaining time 0:25:25

Download speed 8,12 KB
Remaining time 0:23:52

Download speed 8,39 KB
Remaining time 0:22:56

Download speed 169,65 KB
Remaining time 0:00:58

Download speed 591,03 KB
Remaining time 0:00:06

Download speed 393,86 KB
Remaining time 0:00:00

byteSnapshot = 0

你可以看到我做错了什么..下载速度对我来说看起来不太现实，时间已经过去了，但我无法弄清楚这里出了什么问题..

我认为我的问题在于下载速度的计算，所以如果下载速度正确，时间就会固定...

Answer 1

我一直在测试，我认为我找到了解决方案。

我创建了2 BackgroundWorkers

下载过程
计算下载速度

下载过程
这里没有太大的改变..我添加了一个Stopwatch来跟踪下载x字节数所花费的时间。 x个字节存储在currentFileSizeDownloaded中，秒存储在secondsElapsed。

// Download the file
//Console.WriteLine("Downloading \"{0}\" from {1}...", node.Name, Config.FTP_HOST + "/" + node.DirectoryFileIsIn);
FtpWebRequest request = CreateRequest("ftp://" + Config.FTP_HOST + "/" + node.DirectoryFileIsIn + "/" + node.Name, WebRequestMethods.Ftp.DownloadFile.ToString());
FtpWebResponse response = (FtpWebResponse)request.GetResponse();
Stream responseStream = response.GetResponseStream();
FileStream filestream = new FileStream(new_path, FileMode.Create);

// Start stopwatch for calculating download speed
Stopwatch stopwatch = new Stopwatch();
stopwatch.Start();

// Read/write downloaded bytes
int chunkSize = 1024;
long total = node.FileSize;
int streamPosition = 0;
while (true)
{
    byte[] buffer = new byte[Math.Min(chunkSize, node.FileSize - streamPosition)];
    //byte[] buffer = new byte[chunkSize];
    int readBytes = responseStream.Read(buffer, 0, buffer.Length);

    if (readBytes == 0)
        break;

    currentFileSizeDownloaded += readBytes; // total bytes downloaded
    streamPosition += readBytes; // for tracking response stream position

    filestream.Write(buffer, 0, readBytes);
}

// Stop the stopwatch
stopwatch.Stop();
secondsElapsed += stopwatch.Elapsed.TotalSeconds;

filestream.Flush();
//Console.WriteLine("Download Complete, status {0}", response.StatusDescription);

response.Dispose();
filestream.Dispose();

response.Close();
filestream.Close();
}

计算下载速度
这是我计算下载速度的地方，再没有什么大的变化..我正在缓存secondsElapsed，currentFileSizeDownloaded来自下载过程并使用这些精确值进行我的DownloadSpeed计算（而不是使用'10我Thread.Sleep()的秒数。

while (true)
{
    cached_secondsElapsed = secondsElapsed;
    cached_currentFileSizeDownloaded = currentFileSizeDownloaded;

    Thread.Sleep(10000); // Sleep 10 seconds

    long bytesDownloaded = currentFileSizeDownloaded - cached_currentFileSizeDownloaded;
    double secondsItTook = secondsElapsed - cached_secondsElapsed;

    if (bytesDownloaded > 0)
    {
        double downloadSpeed = ((double)bytesDownloaded / secondsItTook); // bytes per second
        long remainingTime = (totalFileSizeToDownload - currentFileSizeDownloaded) / (long)downloadSpeed;
        Console.WriteLine("Download speed {0}", Formatting.FormatBytes((long)downloadSpeed));
        Console.WriteLine("Remaining time {0}", Formatting.FormatSeconds(remainingTime));
        Console.WriteLine();
    }
    else
    {
        Console.WriteLine("bytesDownloaded = 0"); // DEBUG
        Application.Exit(); // Stop the app
    } 
}

<强>输出

Download speed 976,58 KB
Remaining time 0:00:12

Download speed 438,6 KB
Remaining time 0:00:27

Download speed 483,37 KB
Remaining time 0:00:24

Download speed 325,42 KB
Remaining time 0:00:36

Download speed 331,42 KB
Remaining time 0:00:35

Download speed 363,87 KB
Remaining time 0:00:31

Download speed 441,13 KB
Remaining time 0:00:26

Download speed 798,81 KB
Remaining time 0:00:10

Download speed 1,04 MB
Remaining time 0:00:00

bytesDownloaded = 0

这不是那么准确，但它比以前更好...如果有人对我的提示更准确，请发布它们作为答案/评论。

FTP下载估计剩余时间

1 个答案: