Question

我编写了一个Eventhandler（异步调用），我通过它下载任何网页的源字符串（HTML），我通过文本框输入URL并将其传递给调用eventhandler的方法，这样可以正常工作，除非是：

我打开应用程序，什么也不做，按“开始”按钮，打开浏览器，将任何链接复制到某个页面，再次按下“开始”按钮。运行应用程序，然后当我将该链接粘贴到文本框并尝试抓取它时，它在无限循环中卡住我的进度指示器，我尝试刷新页面但它没有帮助，这里是下面的代码： / p>

 public void LoadSiteContent(string url)
 {
        //create a new WebClient object


        var indicator = new ProgressIndicator
        {
            IsVisible = true,
            IsIndeterminate = true,
            Text = "Downloading Source..."
        };

        try
        {
            SystemTray.SetProgressIndicator(this, indicator);

            WebClient client = new WebClient();

            client.DownloadStringCompleted += new DownloadStringCompletedEventHandler(DownloadStringCallback2);

            client.DownloadStringAsync(new Uri(url));
        }
        catch (Exception ex)
        {
            if (ex is TimeoutException || ex is WebException)
            {
                MessageBox.Show("It seems there is no response from the remote server (are you connected to the internet?)");

            }
       }
 }

 private void DownloadStringCallback2(Object sender, DownloadStringCompletedEventArgs e)
 {

            if (!e.Cancelled && e.Error == null)
            {
              //Do whatever with the downloaded string (e.Result)
            }
 }
 private void button1_Click(object sender, RoutedEventArgs e)
 {


        string Entered_URL = "";

        Entered_URL = Enter_URL_Text.Text; //Stored from the textbox


        LoadSiteContent(Entered_URL);
 }

我如何解决这个问题？谢谢！

Answer 1

我已经尝试过你的代码了，它运行得很好。由于ProgressIndicator，我认为它“似乎”陷入了无限循环。您需要在IsIndeterminate方法中更改Text和DownloadStringCallback2属性。

尝试将以下代码添加到DownloadStringCallback2方法中：

private void DownloadStringCallback2(Object sender, DownloadStringCompletedEventArgs e)
    {
        var indicator = SystemTray.GetProgressIndicator(this);
        indicator.IsIndeterminate = false;
        indicator.Text = "";

        if (!e.Cancelled && e.Error == null)
        {
            MessageBox.Show("Page load complete.");

            //Do whatever with the downloaded string (e.Result)
        }
    }

并查看它是否按预期工作。

按下“开始”按钮 - Windows Phone 7后，Web Scraping事件处理程序陷入困境

1 个答案: