我有一個按鈕單擊事件,我做一次,一些列表,並啓動backgroundworker1:我如何確保100%背景工作者不忙,然後再次啓動它?
private void btnDownload_Click(object sender, EventArgs e)
{
btnDownload.Enabled = false;
label7.Text = "Downloading...";
ei.Init();
if (countryList.Count() == 0)
{
foreach (ExtractImages.Continent continent in ei.world.continents)
{
foreach (ExtractImages.Country country in continent.countries)
{
if (country.name == "Israel")
{
foreach (string imageUri in country.imageUrls)
{
countryList.Add(imageUri);
}
}
else
{
foreach (string imageUri in country.imageUrls)
{
newList.Add(imageUri);
}
}
}
}
}
backgroundWorker1.RunWorkerAsync();
}
在DoWork的事件:
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
if (downloaded == false)
{
getTotalBytes(countryList);
CreateCountryDateTimeDirectories(countryList);
downloadFile(countryList);
}
else
{
getTotalBytes(newList);
CreateCountryDateTimeDirectories(newList);
downloadFile(newList);
}
}
在DoWork的事件中,我有兩個階段首先,它將使計算並將下載列表countryList中的鏈接。
我想要做的就是一旦完成再次下載countryLinks start backgroundworker1中的所有鏈接並且這次下載列表newList中的鏈接。
這是我如何下載列表中的鏈接。
private Queue<string> _downloadUrls = new Queue<string>();
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();
}
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), @"c:\temp\TempSatFiles\" + urlCount + "Infrared.jpg");
//await client.DownloadFileTaskAsync(new Uri(url), countriesMainPath + "\\" + currentDownloadCountry + "\\" + urlCount + "Infrared.jpg");
}
else
{
await client.DownloadFileTaskAsync(new Uri(url), @"c:\temp\TempSatFiles\" + urlCount + "Invisible.jpg");
//await client.DownloadFileTaskAsync(new Uri(url), countriesMainPath + "\\" + currentDownloadCountry + "\\" + urlCount + "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;
private async void Completed(object sender, AsyncCompletedEventArgs e)
{
var cnt = System.Threading.Interlocked.Decrement(ref urlCount);
if (cnt > 0)
{
await DownloadFile();
label9.Text = urlCount.ToString();
}
else
{
label7.Text = "Download completed";
downloaded = true;
btnDownload.Enabled = true;
sw.Stop();
}
}
現在它會下載countryList中的鏈接。 當完成下載列表中的所有文件也將獲得else部分:這次在DoWork的事件,將下載的newList鏈接
label7.Text = "Download completed";
downloaded = true;
btnDownload.Enabled = true;
sw.Stop();
在這裏,我要重新啓動backgroundworker1和。
問題是我怎麼知道backgroundworker1不忙?有可能是它下載了所有文件,並且backgroundworker1仍然很忙?
或者我應該在backgroundworker完成的事件中啓動背景工作?如果它完成了所有的下載,它將會到達背景完成的事件?或者首先它會到達webclient完成的事件?
管理多個'BackgroundWorker's總是很尷尬;這是您的代碼已準備好[從BGW升級到'Task.Run']的標誌之一(http://blog.stephencleary.com/2013/05/taskrun-vs-backgroundworker-intro.html)。 –