Question

在我尝试检查显示整体下载进度的progressBar2是否为100％之前，它确实没有用。有没有其他方法可以更有把握地检查它？

private void btnDownload_Click(object sender, EventArgs e)
        {
            //urll.Add("http://download.thinkbroadband.com/1GB.zip");
            btnDownload.Enabled = false;
            label7.Text = "Downloading...";
            getTotalBytes(countryList);
            CreateCountryDateTimeDirectories(newList);
            downloadFile(newList);
        }

        private Queue<string> _downloadUrls = new Queue<string>();

        private async void downloadFile(IEnumerable<string> urls)
        {
            foreach (var url in urls)
            {
                _downloadUrls.Enqueue(url);
            }

            await DownloadFile();
        }

        private async Task DownloadFile()
        {
            if (_downloadUrls.Any())
            {
                WebClient client = new WebClient();
                client.DownloadProgressChanged += ProgressChanged;
                client.DownloadFileCompleted += Completed;

                var url = _downloadUrls.Dequeue();

                sw = Stopwatch.StartNew();

                if (url.Contains("true"))
                {
                    await client.DownloadFileTaskAsync(new Uri(url), countriesMainPath + "\\" + currentDownloadCountry + "\\" + count + "Infrared.jpg");
                }
                else
                {
                    await client.DownloadFileTaskAsync(new Uri(url), countriesMainPath + "\\" + currentDownloadCountry + "\\" + count + "Invisible.jpg");
                }

                return;
            }
        }

        double percentageTotalDownload = 0;
        double totalBytesDownloaded = 0;
        private void ProgressChanged(object sender, DownloadProgressChangedEventArgs e)
        {
            // Calculate download speed and output it to labelSpeed.
            label3.Text = string.Format("{0} kb/s", (e.BytesReceived / 1024d / sw.Elapsed.TotalSeconds).ToString("0.00"));

            // Update the progressbar percentage only when the value is not the same.
            double bytesInCurrentDownload = (double)e.BytesReceived;
            double totalBytesCurrentDownload = double.Parse(e.TotalBytesToReceive.ToString());
            double percentageCurrentDownload = bytesInCurrentDownload / totalBytesCurrentDownload * 100;
            ProgressBar1.Value = int.Parse(Math.Truncate(percentageCurrentDownload).ToString());//e.ProgressPercentage;
                                                                                                // Show the percentage on our label.
            Label4.Text = e.ProgressPercentage.ToString() + "%";

            // Update the label with how much data have been downloaded so far and the total size of the file we are currently downloading
            label10.Text = string.Format("{0} MB's / {1} MB's",
                (e.BytesReceived / 1024d / 1024d).ToString("0.00"),
                (e.TotalBytesToReceive / 1024d / 1024d).ToString("0.00"));

            //Let's update ProgressBar2
            totalBytesDownloaded = e.BytesReceived + bytesFromCompletedFiles;
            percentageTotalDownload = totalBytesDownloaded / totalBytesToDownload * 100;
            progressBar2.Value = (int)percentageTotalDownload;
            label6.Text = progressBar2.Value.ToString() + "%";
        }

        long bytesFromCompletedFiles = 0;
        // The event that will trigger when the WebClient is completed
        private async void Completed(object sender, AsyncCompletedEventArgs e)
        {
          await DownloadFile();
        }

例如，如果我有100个网址并且它开始下载，那么我想在已完成的事件中知道所有下载的文件，而不是每次只有一个。

Answer 1

您可以跟踪计数器变量中已完成的下载量。由于可以访问该计数器的多个线程，使用Interlocked类来操作该计数器。

这是您的代码中所需的更改：

private int urlCount = 0; // keep track of how many urls are processed

private async void downloadFile(IEnumerable<string> urls)
{
    urlCount = 0;
    foreach (var url in urls)
    {
        _downloadUrls.Enqueue(url);
        urlCount++;
    }
    // urlCount is now set
    await DownloadFile();
}

这是处理柜台和检查我们是否完成

private async void Completed(object sender, AsyncCompletedEventArgs e)
{
    // urlCount will be decremented
    // cnt will get its value
    var cnt = System.Threading.Interlocked.Decrement(ref urlCount);

    if (cnt > 0) {
        await DownloadFile();
    } 
    else
    {
        // call here what ever you want to happen when everything is 
        // downloaded
        "Done".Dump();
    }
}

Answer 2

我对此并不了解，但您要完成的是您的进度条显示下载所有文件的进度，而不是一个文件，然后重置另一个重置的文件。

如果是这种情况，那么为什么你不尝试foreach文件获取大小并将其加总为totalBytesToDownload然后在进度条中使用它

所以

foreach(string url in urll)
{
    //get url file size
    totalBytesToDownload = totalBytesToDownload + urlSizeYouGot;
}

如何检查是否已下载所有文件？

2 个答案: