ASP.NET 3.5: Display UpdateProgress during Page_Lo

问题:

I am building an ASP.NET site using Visual Studio 2008 and have a page looking like this (stuff snipped)

<asp:Content ID="Content2" ContentPlaceHolderID="PageContentPlaceHolder" runat="server">
    <asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
        <ContentTemplate>
            the page here..
        </ContentTemplate>
    </asp:UpdatePanel>
    <asp:UpdateProgress ID="UpdateProgress1" runat="server" DisplayAfter="100">
        <ProgressTemplate>
            <div>
                <asp:Image ID="AjaxImage" runat="server" ImageUrl="Ajax.gif" />
            </div>
        </ProgressTemplate>
    </asp:UpdateProgress>
</asp:Content>

The page_load starts a long (>5s) process

protected void Page_Load(object sender, EventArgs e)
{            
  if (!IsPostBack)            
  {
    LongRunningProcess();                
  }
}

How can I display the UpdateProgress while the LongRunningProcess is running? It does work when I move the LongRunningProcess() call to a button onclick handler.

回答1:

Create a normal div that shows the Ajax.gif so it shows "processing" by default.

In the javascript pageLoad() function, make a call back to the page using Ajax's PageMethods.

   function pageLoad(sender, args) {
                PageMethods.getVersions(LoadVersionsCallback);
    }

The method you are calling in your .aspx.cs file has to be static, it can take parameters and looks something like:

   [System.Web.Services.WebMethod]
    public static string getVersions()
    {
      StringBuilder sb = new StringBuilder();
       ... etc.
      return sb.ToString();

    }

The javascript function that you specified when you called the method will run when the method completes. It will be passed the results. At the end of this function you hide the Ajax.gif div.

   function LoadVersionsCallback(result) {
    // do something with the results - I load a dropdown list box.

   ...etc. 
    // here is where you hide your div holding the Ajax.gif  

   }

And then you work on making whatever it is you are doing run in less than 1 second....

回答2:

1. Move your page_load code into a new function.
2. Add a AJAX timer into the ContentTemplate section of your page. Set the interval to 500. (1/2 second)
3. Double-click on the Timer object in Design view to create a _tick handler.

4. In the _tick handler created in the previous step, call the following code

   protected void My_Timer_Tick(object sender, EventArgs e)
   {
       My_Timer_Name.Enabled = false;
       My_Page_Load_Function(); // Function created in step 1 above)
   }
   
   protected void My_Page_Load_Function()
   {
       System.Threading.Thread.Sleep(5000); // A delay to simulate doing something.
       lblMyLabel.Text = "Done!";  // Write output to page. 
   } 
   

回答3:

I would put a Ajax timer on the page and set it for less than a second... It will only run once and after its first tick then you need to disable it otherwise it will fire again. (you don't want to start your long running process more than once...)

then on the OnTimerTick event I would start your long running process that way your page fully renders and you can display your UpdateProgress while its running.

you out to be able to move the code that you had for your button click to the time tick...

回答4:

I used JBrooks idea above (i.e. showing the progress indicator as part of a Panel that also includes the Iframe, so that it shows even before the Iframe first loads), but simplified it: style the iframe so that when it does appear it is on top of the animated GIF.

Requires no Javascript or C# code-behind.

Here's the relevant ASPX, followed by the CSS. You'll have to noodle with the "top" setting in the style to cover the image you use.

            <asp:Panel ID="DetailPanel" runat="server" CssClass="submitBox detailPanel">
                <asp:Table ID="Table1" runat="server" Width="100%">
                    <asp:TableHeaderRow ID="TableHeaderRow10" runat="server">
                        <asp:TableCell ID="TableHeaderCell" runat="server"
                            Font-Bold="true" HorizontalAlign="Center">
                        Title Text
                        </asp:TableCell>
                    </asp:TableHeaderRow>
                    <asp:TableRow>
                        <asp:TableCell HorizontalAlign="Center">
                            <asp:Image ID="Image1" runat="server" ImageUrl="~/Images/animated_progress.gif" />
                        </asp:TableCell>
                    </asp:TableRow>
                </asp:Table>
                <div class="iframeOverlay">
                    <iframe id="IframeDetail" runat="server" style="width: 100%; height: 100%;" />
                </div>
            </asp:Panel>

.iframeOverlay { z-index: 2; position: relative; top: -50px; }

回答5:

With Jquery.

<script>
 $(document).ready(function() {
 $('#<%= UpdateProgress1.ClientID %>').show(); 
 });
</script>

回答6:

<script>  $(document).ready(function() {  $('#<%=
UpdateProgress1.ClientID %>').show();   }); </script>

This worked well for me, just had to add it to the end of the BODY section and works like a charm.