WebBrowser等待页面加载DocumentCompleted事件

Question

我正在使用Asp.Net中的WebBrowser控件。我需要等待DocumentComplete事件中的页面加载。问题在于DocumentComplete事件仅被调用一次。

我在做什么错了？

我的代码：

public partial class HpdScrape : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        getHpdInfo(); 
    }

     protected void getHpdInfo()
    {
        Thread thread = new Thread(delegate()
        {
            using (WebBrowser browser = new WebBrowser())
            {
                browser.AllowNavigation = true;
                browser.Navigate("https://hpdonline.hpdnyc.org/HPDonline/provide_address.aspx");
                browser.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(DocumentCompleted);
                while (browser.ReadyState != WebBrowserReadyState.Complete)
                {
                    System.Windows.Forms.Application.DoEvents();
                }

            }
        });
        thread.SetApartmentState(ApartmentState.STA);
        thread.Start();
        thread.Join();
    }

     private void DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
     {
         WebBrowser browser = sender as WebBrowser;

     if (browser.Url.ToString() == "https://hpdonline.hpdnyc.org/HPDonline/provide_address.aspx")
     {
         var doc = browser.Document;
         doc.GetElementById("ddlBoro").SetAttribute("value", "2");
         doc.GetElementById("txtHouseNo").InnerText = "1500";
         doc.GetElementById("txtStreet").InnerText = "Washington";
         doc.GetElementById("btnSearch").InvokeMember("Click");
         // after new page loads this function should get called again...

     }

     else if (browser.Url.ToString() == "https://hpdonline.hpdnyc.org/hpdonline/select_application.aspx")
     {
         //code for after 2nd page load.
     }                 
   }
}