/// <summary>
/// 下载结束后重新尝试下载失败的图片（异步）
/// </summary>
/// <returns>Task</returns>
public static async Task ReTryAsync()
{
Debug.WriteLine("成功：" + "开始Retry");
List <ImageModel> failsList = new List <ImageModel>();
DownloadFailImages.ForEach(img => failsList.Add(img));
DownloadFailImages.Clear();
DelegateCommands.SetImageDownloadFailCountCommand?.Invoke(DownloadFailImages.Count());
await downloadImagesParallel(failsList);
if (UnAvailablePages.Count != 0)
{
List <ImagePageModel> failImagePages = new List <ImagePageModel>();
UnAvailablePages.ForEach(page => failImagePages.Add(page));
UnAvailablePages.Clear();
DelegateCommands.SetUnavailableImagePageCountCommand?.Invoke(UnAvailablePages.Count());
List <ImageModel> imageModels = await getAllImageUrls(failImagePages);
await downloadImagesParallel(imageModels);
}
SoundPlayer.PlayCompleteness();
new Window_FinishResult().Show();
}
public static async Task StartDownload(ObservableCollection <TaskItem> taskItems)
{
DownloadFailImages.Clear();
DownloadFinishImages.Clear();
UnAvailablePages.Clear();
for (int i = 0; i < taskItems.Count; i++)
{
await downloadATask(taskItems[i]);
}
SoundPlayer.PlayCompleteness();
new Window_FinishResult().Show();
}
/// <summary>
/// 从网页中查找图片链接并下载到本地（异步）
/// </summary>
/// <param name="imagePageUrls">一组网页的Url</param>
/// <param name="taskItem">该组网页所属的TaskItem</param>
/// <returns>Task</returns>
private static async Task downloadImagesParallel(List <ImageModel> imageModelList)
{
Object lockObj = new Object();
List <Task> taskList = new List <Task>();
var limitation = new SemaphoreSlim(ParallelTaskNum);
foreach (ImageModel imageModel in imageModelList)
{
//ImageModel imageModelTemp = imageModel;
await limitation.WaitAsync();
//把Task添加到线程池中
taskList.Add(Task.Run(async() =>
{
try
{
await downloadAImageAndSave(imageModel);
lock (lockObj)
{
imageModel.ImagePage.TaskItem.NumberOfFinish++;
DownloadFinishImages.Add(imageModel);
DelegateCommands.SetImageDownloadCountCommand?.Invoke(DownloadFinishImages.Count());
}
}
catch (Exception e)
{
lock (lockObj)
{
DownloadFailImages.Add(imageModel);
DelegateCommands.SetImageDownloadFailCountCommand?.Invoke(DownloadFailImages.Count());
}
}
finally
{
limitation.Release();
}
}));
}
//等待所有Task完成
await Task.WhenAll(taskList);
}