设置控件是否是异步回发

aspx

     < form id = " form1 "  runat = " server " >
         < asp:ScriptManager ID = " ScriptManager1 "  runat = " server " >
         </ asp:ScriptManager >
        
         < asp:UpdatePanel ID = " UpdatePanel1 "  runat = " server "  UpdateMode = " Conditional " >
             < ContentTemplate >
                 <%=  DateTime.Now  %>
                 < asp:Button ID = " Button2 "  runat = " server "  Text = " Button "   />
             </ ContentTemplate >
         </ asp:UpdatePanel >
        
         < asp:Button ID = " Button1 "  runat = " server "  Text = " Button "  OnClick = " Button1_Click "   />
     </ form >

cs

     protected   void  Page_Load( object  sender, EventArgs e)
    {
        ScriptManager.GetCurrent( this ).RegisterAsyncPostBackControl( this .Button1);
        ScriptManager.GetCurrent( this ).RegisterPostBackControl( this .Button2);
    }

     protected   void  Button1_Click( object  sender, EventArgs e)
    {
         this .UpdatePanel1.Update();
    }