5.4 由JavaScript来更新UpdatePanel_决战.NET-QQ阅读中文科幻网

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5.4 由JavaScript来更新UpdatePanel

经过了Single Page架构的震撼教育后，让我们轻松一点谈谈UpdatePanel的更新动作控制，除了可以通过Trigger、Update函数来更新UpdatePanel外，设计师也能通过JavaScript，从客户端要求更新某一个UpdatePanel，这在许多情况下会相当的有用。那具体该如何做呢？说来也很简单，只要在JavaScript调用__doPostback函数，传入要更新的UpdatePanel即可，程序5-10是本例所使用的.aspx源码，程序5-11则是.cs文件。

程序5-10

    Samples\5\AdvAjaxDemo\RefreshUpdateWithJavaScript2.aspx
    <%@ Page Language="C#" AutoEventWireup="true" CodeFile=
      "RefreshUpdateWithJavaScript2.aspx.cs" Inherits=
      "RefreshUpdateWithJavaScript2" %>
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
      "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml" >
    <head runat="server">
        <title>Untitled Page</title>
    </head>
    <body>
        <form id="form1" runat="server">
        <div>
          <asp:ScriptManager ID="ScriptManager1" runat="server">
            </asp:ScriptManager>
            <script language=javascript>
            function confirmRefresh()
            {
              if(confirm("do you want refresh?"))
              {
                __doPostback("UpdatePanel1","Refresh");
              }
            }
            </script>
            <input id="Button1" type="button" value="Refresh Panel" onclick=
              "confirmRefresh()"/>
            <asp:UpdatePanel ID="UpdatePanel1" runat="server"
              UpdateMode="Conditional">
                <ContentTemplate>
                    <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
                </ContentTemplate>
            </asp:UpdatePanel>   &nbsp;
        </div>
        </form>
    </body>
    </html>

程序5-11

    Samples\5\AdvAjaxDemo\RefreshUpdateWithJavaScript2.aspx.cs
    using System;
    using System.Data;
    using System.Configuration;
    using System.Collections;
    using System.Web;
    using System.Web.Security;
    using System.Web.UI;
    using System.Web.UI.WebControls;
    using System.Web.UI.WebControls.WebParts;
    using System.Web.UI.HtmlControls;
    public partial class RefreshUpdateWithJavaScript2 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (ScriptManager1.IsInAsyncPostback &&
              ScriptManager1.AsyncPostbackSourceElementID == "UpdatePanel1")
            {
                Label1.Text = DateTime.Now.ToString();
            }
        }
    }

很简单不是？