PRM–initializeRequest事件

PRM–initializeRequest事件
•参数类型：InitializeRequestEventArgs
–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
–取消此次异步更新

优先级高的异步刷新
aspx

<% @ Page Language = " C# "  MasterPageFile = " ~/Site.master "  AutoEventWireup = " true "  CodeFile = " 1_PrecedencePostBack.aspx.cs "  Inherits = " _1_PrecedencePostBack "  Title = " PrecedencePostBack "   %>
< asp:Content ID = " Content1 "  ContentPlaceHolderID = " ContentPlaceHolder1 "  Runat = " Server " >

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

< asp:UpdatePanel ID = " UpdatePanel1 "  runat = " server " >
     < ContentTemplate >
         <%=  DateTime.Now  %>< br  />
         < asp:Label ID = " Label1 "  runat = " server "  Text = "" ></ asp:Label >< br  />
         < asp:Button ID = " btnPrecedence "  runat = " server "  Text = " 优先 "  OnClick = " Button_OnClick "   />
         < asp:Button ID = " Button2 "  runat = " server "  Text = " 普通 "  OnClick = " Button_OnClick "   />
     </ ContentTemplate >
</ asp:UpdatePanel >

< script type = " text/javascript "  language = " javascript " >
    var lastPostBackButtonId  =   null ;
    var btnPrecedenceId  =   " <%= this.btnPrecedence.ClientID %> " ;
    
    Sys.WebForms.PageRequestManager.getInstance().add_initializeRequest(
        function(sender, e)
        {
            var prm  =  Sys.WebForms.PageRequestManager.getInstance();
             if  (prm.get_isInAsyncPostBack())
            {
                 if  (lastPostBackButtonId  ==  btnPrecedenceId)
                {
                    e.set_cancel( true );
                    
                     if  (e.get_postBackElement().id  ==  btnPrecedenceId)
                    {
                        showMessage( " 不可重复发起优先的刷新。 " );
                    }
                     else
                    {
                        showMessage( " 请等待优先的刷新结束。 " );
                    }
                    
                     return ;
                }
                 else   if  (e.get_postBackElement().id  ==  btnPrecedenceId)
                {
                    showMessage( " 发起优先的刷新，普通的刷新将被取消。 " );
                }
                 else
                {
                    showMessage( " 重新发起普通的刷新，前一次提交将被取消。 " );
                }
            }
            
            lastPostBackButtonId  =  e.get_postBackElement().id;
        });
</ script >

</ asp:Content >

cs

     protected   void  Page_Load( object  sender, EventArgs e)
    {

    }

     protected   void  Button_OnClick( object  sender, EventArgs e)
    {
        Thread.Sleep( 3000 );

        Button button  =  sender  as  Button;
         this .Label1.Text  =  String.Format( " 您点击了“{0}”按钮 " , button.Text);
    }

使用Thread.Sleep( 3000 );需要导入命名空间 System.Threading;