UpdatePanel的用法

UpdateMode： 表示UpdatePanel的更新模式，有两个选项：Always和Conditional。Always是无论有没有Trigger，其它控件都将更新该UpdatePanel，Conditional表示仅仅有当前UpdatePanel的Trigger，或ChildrenAsTriggers属性为true时当前UpdatePanel中控件引发的异步回送或者整页回送，或是server端调用Update()方法才会引发更新该UpdatePanel。
Contente Template：用来定义UpdatePanel的内容
Triggers：分别为AsyncPostBackTrigger和PostBackTrigger
AsyncPostBackTrigge用来指定某个server端控件以及其将触发的server端事件作为该UpdatePanel的异步更新触发器，它须要设置的属性有控件ID和服务端控件的事件；PostBackTrigger用来指定在UpdatePanel中的某个服务端控件，它所引发的回送不使用异步回送，而仍然是传统的整页回送
如今我们来做一个简单的实例：

<% @ Page Language = " C# "  AutoEventWireup = " true "  CodeFile = " Default.aspx.cs "  Inherits = " _Default "   %>

<! DOCTYPE html PUBLIC  " -//W3C//DTD XHTML 1.1//EN "   " http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd " >
< html xmlns = " http://www.w3.org/1999/xhtml " >
< head runat = " server " >
     < title > Untitled Page </ title >
     < style type = " text/css " >
         body  { background - attachment: fixed ;
             
              
                background - image:url(Blue hills.jpg);
                }
                
         .style1
          {
                background - position:top center;
         }
         
         
     </ style >

</ head >
< body  onload = " oSpan.className='style1' "   >
     < form id = " form1 "  runat = " server " >
     < span style = " font-size:14; width:250; "  ID = " oSpan "
        onmouseover = " this.className='style2' "  onmouseout = " this.className='style1' " ></ span >
         < div >
             < asp:ScriptManager ID = " ScriptManager1 "      runat = " server " >     
               </ asp:ScriptManager >
         </ div >
           
         < asp:UpdatePanel ID = " uid "   runat = " server " >
        
             < ContentTemplate >
            
                 < div  >
                     < asp:Button ID = " Button1 "  runat = " server "  Text = " 异步回送 "  OnClick = " Button1_Click1 "   />& nbsp; & nbsp;
                     < asp:Button ID = " Button2 "  runat = " server "  Text = " 整页回送 "  OnClick = " Button2_Click "   />< br  />
                     < asp:GridView ID = " GridView1 "  runat = " server "  AutoGenerateColumns = " False "  Width = " 197px " >
                         < Columns >
                             < asp:BoundField DataField = " au_lname "  FooterText = " aaaa "  HeaderText = " au_lname "   />
                         </ Columns >
                     </ asp:GridView >
                     < br  />
                    < asp:Label ID = " Label1 "  runat = " server "  Text = " 当前时间 "  Font - Bold = " True "  Font - Size = " Large " ></ asp:Label >
                   </ div >
             </ ContentTemplate >
             < Triggers >
                 < asp:AsyncPostBackTrigger    ControlID = " Button1 "   />
                 < asp:PostBackTrigger  ControlID = " Button2 "   />
             </ Triggers >
              
         </ asp:UpdatePanel >
           < div id = " div1 "   >
               & nbsp; </ div >
        
        
     </ form >
</ body >
</ html >