How realizes the postback event in the cache page

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Hi,
I use post way realization page postback this am must,How realizesunder the
post way controls postback continuously to be unable to findthe solution the
method to hope can obtain master's help in here

Cannotuse VaryByControl
code:
<%@ OutputCache Duration="100000" VaryByParam="page;category" %>
<%= DateTime.Now.ToString() %>
<asp:Button ID="button1" runat=server Text="click"
OnClick="Button1_Click" />
<asp:Label ID="label1" runat=server></asp:Label>

protected void Button1_Click(object sender, EventArgs e)
{
this.label1.Text = DateTime.Now.ToString();
}
i have used other codes cannot realize:
protected void Page_Load(object sender, EventArgs e)
{
ClientScriptManager cs = Page.ClientScript;

// Create a button element with its onClick attribute defined
// to create a postback event reference to the custom label control.
HtmlInputButton b = new HtmlInputButton();
b.ID = "mybutton1";
b.Value = "Click";
b.Attributes.Add("onclick", cs.GetPostBackEventReference(this,
b.ID.ToString()));
PlaceHolder1.Controls.Add(b);
PlaceHolder1.Controls.Add(new LiteralControl("<br/>"));

HtmlInputButton c = new HtmlInputButton();
c.ID = "mybutton2";
c.Value = "Click";
c.Attributes.Add("onclick", cs.GetPostBackEventReference(this,
c.ID.ToString()));
PlaceHolder1.Controls.Add(c);
PlaceHolder1.Controls.Add(new LiteralControl("<br/>"));

// Create a link element with its href attribute defined
// to create a postback event reference to the custom label control.
HtmlAnchor a = new HtmlAnchor();
a.ID = "myanchor1";
a.InnerText = "link";
a.HRef = cs.GetPostBackClientHyperlink(this, a.ID.ToString());
PlaceHolder1.Controls.Add(a);
}
void IPostBackEventHandler.RaisePostBackEvent(string eventArgument)
{
Label1.Text = "Postback handled by " + this.ID.ToString() + ".
<br/>" +
"Postback caused by " + eventArgument.ToString() +
"."; ;
}