在asp.net c#中延迟显示消息一段时间

Question

I have a label, all what I want is, to display label as "name1" then wait for 5 seconds and then change it to "name2". This is how I did that

protected void Page_Load(object sender, EventArgs e)
{
   Label1.Text = "name1";
   System.Threading.Thread.Sleep(5000);
   Label1.Text = "name2";
}

What it does is it wait's for 5 seconds in total and then display "name2". "name1" is not displaying as I wished. I tried these links,

How do I get my C# program to sleep for 50 msec?

How to trigger a timer tick programmatically?

Did not help. This Using the ASP.NET Timer Control with Multiple UpdatePanel Controls seems to work but this is keep on refreshing the page. I don't want this to happen, it should display name1 then wait for 5 seconds, display name2 and then stop.

Answer 1

您提到的更改必须在客户端，使用 javascript setTimer 方法并将标签更新为您需要的任何文本。

Answer 2

You can use Timer control in your page under UpdatePanel for Async functionality (for help on AJAX in ASP.net below are the links provided) , and then under its event use this logic for label name change:

 protected void Page_Load(object sender, EventArgs e)
 {
    Timer1.Enabled = true;
    Timer1.Interval = 5000;
 }

 protected void Timer1_Tick(object sender, EventArgs e)
 {
    if(Label1.Text == "name2")
    {
        Label1.Text = "name1";
    }
    else
    {
        Label1.Text = "name2";
    }
 }

for more help on this you can check here and here

Answer 3

You cannot handle this the way you have in ASP.NET since you will always get the end result from the form_load event. You will have to use JavaScript timing events to handle this at the client side.

      <script>
                $(document).ready(function(){
                 $('#label').val('label1');
                 setTimeout(SetLabel2, 5000); //wait for 5 seconds before setting the label. NOTE: This will keep on repeating until you clear the timeout
                });

                function SetLabel2(){
                  var l = $('#label).val();
                  if(l == 'label2)
                  {
                     window.clearTimeOut(); //So that this does not repeat
                  }
       </script>

Answer 4

As suggested by other contributors, you should use client code to obtain that kind of behavior. In your code sample, the Page_Load function simply takes 5 seconds to execute, and when all the processing on the server is done, the resulting HTML is finally sent to the browser... and you see "name2".

Here is a jQuery version of the client code:

$(document).ready(function () {
    $('#Label1').html("name1");
    setTimeout(function () { $('#Label1').html("name2"); }, 5000);
})

and here is a pure Javascript version:

var lbl1 = document.getElementById('Label1');
lbl1.innerHTML = "name1";
setTimeout(function () { lbl1.innerHTML = "name2" }, 5000);

If the ID of the Label is mangled by ASP.NET, you can use <%= Label1.ClientID %> instead of Label1 in the client code.

Answer 5

This could be done using only what is provided, it should run once, so once the tick is complete we disable the timer.

protected void Page_Load(object sender, EventArgs e)
{
    Timer1.Enabled = true;
    Label1.Text = "name1";
    Timer1.Interval = 2000;
}

protected void Timer1_Tick(object sender, EventArgs e)
{
    Label1.Text = "name2";
    Timer1.Enabled = false;
}