Question

我不确定如何说出我的问题。我试图在foreach循环中下载500个csv文件，我正在下载的东西出错。所以我在每个webClient.DownloadFile调用之前和之后放了一个.text输出。问题是我似乎没有输出每个.text文件;如果它成功，它将在结束时全部输出，如果失败则不输出任何。我不知道有一些线索/小修道具。谁能帮助我做我想做的事情？谢谢（这方面的菜鸟）。以下是我的代码。

foreach (var ticker in tickers)
    {
        tbOutput.Text += "Starting Download of : " + ticker + "\n";

        var url = string.Format(urlPrototype, ticker, startMonth, startDay, startYear, finishMonth, finishDay, finishYear, "d");
        var csvfile = directory + "\\" + ticker.ToUpper() + ".csv";

        webClient.DownloadFile(url, csvfile);

        tbOutput.Text += "End Download of : " + ticker + "\n";
    }

Answer 1

很难说你演唱的是什么技术，但是你最有可能会调用一个事件或者回复，所以你在完全执行后得到结果，如果你想看到你下载的每个文件的进度你可以尝试使用像

这样的想法

WebClient.DownloadFileCompleted Event

Answer 2

尝试使用DownloadFile，因为它会抛出WebException。 https://msdn.microsoft.com/en-us/library/ez801hhe%28v=vs.100%29.aspx

foreach (var ticker in tickers)
{
    tbOutput.Text += "Starting Download of : " + ticker + "\n";

    var url = string.Format(urlPrototype, ticker, startMonth, startDay, startYear, finishMonth, finishDay, finishYear, "d");
    var csvfile = directory + "\\" + ticker.ToUpper() + ".csv";

    ThreadPool.QueueUserWorkItem((o) =>
    {
        try
        {
            webClient.DownloadFile(url, csvfile);
            System.Windows.Application.Current.Dispatcher.Invoke(new Action(() =>
            {
                //do something or output like
                tbOutput.Text += "End Download of : " + ticker + " (OK)\n";
            }));
        }
        catch (Exception ex)
        {
            System.Windows.Application.Current.Dispatcher.Invoke(new Action(() =>
            {
               //do something or output like
               tbOutput.Text += "End Download of : " + ticker + " (FAIL)\n";
            }));
        }
        finally
        {
            System.Windows.Application.Current.Dispatcher.Invoke(new Action(() =>
            {
                //do something or output like
                //tbOutput.Text += "End Download of : " + ticker + "\n";
            }));
        }
    }
}

将文本输出到webClient.DownloadFile循环中的文本框

2 个答案: