AJAX刷新Gridview

using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

public partial class _Default : System.Web.UI.Page    
{
        

        System.Data.DataView CreateDataSourceByXianhuiMeng()
        {
                System.Data.DataTable dt = new System.Data.DataTable();
                System.Data.DataRow dr;
                dt.Columns.Add( new System.Data.DataColumn( "id", typeof(System.Int32)));
                dt.Columns.Add( new System.Data.DataColumn( "学生姓名", typeof(System.String)));
                dt.Columns.Add( new System.Data.DataColumn( "语文", typeof(System.Decimal)));
                dt.Columns.Add( new System.Data.DataColumn( "数学", typeof(System.Decimal)));
                dt.Columns.Add( new System.Data.DataColumn( "英语", typeof(System.Decimal)));
                dt.Columns.Add( new System.Data.DataColumn( "计算机", typeof(System.Decimal)));

                 for ( int i = 1; i < 30; i++)
                {
                        System.Random rd = new System.Random(Environment.TickCount * i); ;
                        dr = dt.NewRow();
                        dr[0] = i;
                        dr[1] = "【孟子E章】" + i.ToString();
                        dr[2] = System.Math.Round(rd.NextDouble() * 100, 2);
                        dr[3] = System.Math.Round(rd.NextDouble() * 100, 2);
                        dr[4] = System.Math.Round(rd.NextDouble() * 100, 2);
                        dr[5] = System.Math.Round(rd.NextDouble() * 100, 2);
                        dt.Rows.Add(dr);
                }
                System.Data.DataView dv = new System.Data.DataView(dt);
                 return dv;
        }

         protected void Page_Load( object sender, EventArgs e)
        {
                 if (Request.QueryString[ "id"] != null)
                {
                        Response.ClearContent();
                        GridView1.DataSource = CreateDataSourceByXianhuiMeng();
                        GridView1.DataBind();
                        System.Text.StringBuilder sb = new System.Text.StringBuilder();
                        System.IO.StringWriter sw = new System.IO.StringWriter(sb);
                        HtmlTextWriter htw = new HtmlTextWriter(sw);
                        Literal header = new Literal();
                        header.Text = "<h2>项目 " + Request.QueryString[ "id"] + "</h2>";
                        Header.Controls.Add(header);
                        Header.RenderControl(htw);
                        GridView1.RenderControl(htw);
                        Response.Write( "这里查询数据，输出结果就可以了。结果：" + sb.ToString());
                        Response.End();
                }
        }


         public override void VerifyRenderingInServerForm(Control control)
        { }


}

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

< !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 >AJAX练习 </title>
         < script type ="text/javascript" >
        function GetData(p) {
            document.getElementById("d").innerHTML = "正在读取数据……";
            h = window.XMLHttpRequest ? new window.XMLHttpRequest() : new ActiveXObject("MSXML2.XMLHTTP");
            h.open("GET", ' < %=Request.FilePath % >?id=' + p.value, true);
            h.onreadystatechange = function() {
                if (h.readyState == 4) {
                    if (h.status >= 200 && h.status < 300) {
                        document.getElementById("d").innerHTML = h.responseText;
                    }
                    else {
                        document.getElementById("d").innerHTML = " < h2 >数据操作错误： </h2>" + h.responseText;
                    }
                }
            }
            h.send(null);
        }
        alert("这个提示，只出现在第一次打开页面。");
     </script>

</head>
< body >
         < form id ="form1" runat ="server" >
     < asp:GridView ID ="GridView1" runat ="server" GridLines ="Horizontal" Width ="100%" >
             < HeaderStyle BackColor ="#00CCFF" />
             < AlternatingRowStyle BackColor ="#CCCCCC" />
         </asp:GridView>
     < asp:Panel ID ="Header" runat ="server" > </asp:Panel>
     < select onchange ="GetData(this)" >
         < option value ="1" >项目一 </option>
         < option value ="2" >项目二 </option>
     </select>
     </form>
     < div id ="d" > </div>

</body>
</html>