Application Dispatcher 不更新也不报错

Question

我有一个应用程序，我需要下载很多文件。实际上下载我使用这个代码：

System.Net.ServicePointManager.DefaultConnectionLimit = Int32.Parse(Properties.Settings.Default["download_threads"].ToString());
var block = new System.Threading.Tasks.Dataflow.ActionBlock<string>(async url =>
{
    await DownloadLibraries(url);
}, new ExecutionDataflowBlockOptions { MaxDegreeOfParallelism = Int32.Parse(Properties.Settings.Default["download_threads"].ToString()) });

foreach (var url in urls)
{
    block.Post(url);
}

block.Complete();
await block.Completion;

它工作得很好，它通过并行下载下载了我需要的一切。在 DownloadLibraries 方法中，我想更新一个标签。这是代码：

Application.Current.Dispatcher.Invoke(new Action(() =>
{
    string urlnum = this.filesToDownload.Content.ToString().Split('/')[0];
    if (Array.IndexOf(urls, url) > Int32.Parse(urlnum))
        this.filesToDownload.Content = Array.IndexOf(urls, url) + "/" + count.ToString();

    if ((Array.IndexOf(urls, url) * 100) > totalProgress.Value)
        this.totalProgress.Value = (Array.IndexOf(urls, url) * 100) / count;
}));

它没有给我任何错误，但它也没有更新标签。如果我做 Console.Write((Array.IndexOf(urls, url) * 100) / count);它工作正常，我可以在 visual studio 中的输出 space 中看到百分比上升，但标签根本没有更新。可能是什么问题？

Answer 1

您应该在元素的 Dispatcher:

上调用 .Invoke()

this.filesToDownload.Dispatcher.Invoke(new Action(() =>
{
    string urlnum = this.filesToDownload.Content.ToString().Split('/')[0];
    if (Array.IndexOf(urls, url) > Int32.Parse(urlnum))
        this.filesToDownload.Content = Array.IndexOf(urls, url) + "/" + count.ToString();

    if ((Array.IndexOf(urls, url) * 100) > totalProgress.Value)
        this.totalProgress.Value = (Array.IndexOf(urls, url) * 100) / count;
}));

Application Dispatcher 不更新也不报错

Application Dispatcher doesn't update and doesn't give errors

c#

wpf

multithreading

dispatcher

tpl-dataflow