PRM –beginRequest事件

PRM –beginRequest事件
•参数类型：BeginRequestEventArgs
–request属性：用于获得WebRequest对象（用于请求的信息）
–postBackElement：触发异步刷新的DOM元素
•常用操作：
–读取请求信息
–改变请求方式（替换Executor）
–显示更新提示

强制显示UpdateProgress
aspx

< asp:Content ID = " Content1 "  ContentPlaceHolderID = " ContentPlaceHolder1 "  Runat = " Server " >

< asp:UpdatePanel ID = " UpdatePanel1 "  runat = " server " >
     < ContentTemplate >
         <%=  DateTime.Now  %>< br  />
         < asp:Button ID = " Button1 "  runat = " server "  Text = " Button1 "  OnClick = " Button_OnClick "   />
     </ ContentTemplate >
     < Triggers >
         < asp:AsyncPostBackTrigger ControlID = " Button2 "   />
     </ Triggers >
</ asp:UpdatePanel >

< asp:UpdateProgress ID = " UpdateProgress1 "  runat = " server "  DisplayAfter = " 0 "  DynamicLayout = " false "
    AssociatedUpdatePanelID = " UpdatePanel1 " >
     < ProgressTemplate >
         < span style = " color:Red " > Loading </ span >
     </ ProgressTemplate >
</ asp:UpdateProgress >

< hr  />
< asp:Button ID = " Button2 "  runat = " server "  Text = " Button2 "  OnClick = " Button_OnClick "   />


< script language = " javascript "  type = " text/javascript " >
    Sys.WebForms.PageRequestManager.getInstance().add_beginRequest(
        function(sender, e)
        {
             if  (e.get_postBackElement().id  !=   " <%= this.Button2.ClientID %> " )
            {
                 return ;
            }
            
            var updateProgress  =  $ get ( " <%= this.UpdateProgress1.ClientID %> " );
            var dynamicLayout  =   <%=   this .UpdateProgress1.DynamicLayout.ToString().ToLower()  %> ;
            
             if  (dynamicLayout)
            {
                updateProgress.style.display  =   " block " ;
            }
             else
            {
                updateProgress.style.visibility  =   " visible " ;
            }
        });
</ script >

</ asp:Content >

cs

     protected   void  Page_Load( object  sender, EventArgs e)
    {

    }

     protected   void  Button_OnClick( object  sender, EventArgs e)
    {
        Thread.Sleep( 2000 );
    }