vs2005beta2 中通过
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" %>
<!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> <script>
function ClientCallback(result, context) 
{ 
var dropdown2 = document.forms[0].elements['DropDownList2']; dropdown2.innerHTML= ""; var rows = result.split('|'); alert(result.length); for (var i = 0; i < rows.length - 1; ++i) { var values = rows[i] var option = document.createElement("OPTION"); option.value = values; option.innerHTML = values; dropdown2.appendChild(option); 
} } function GetOrders(arg, context) { <%= callBack %> ; } 
</script></head><body> <form id="form1" runat="server"> <div> <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:pubsConnectionString2 %>" SelectCommand="SELECT [au_id], [au_lname], [au_fname] FROM [authors]"> </asp:SqlDataSource> <asp:DropDownList ID="DropDownList1" runat="server"> </asp:DropDownList> <asp:DropDownList ID="DropDownList2" runat="server"> </asp:DropDownList></div> </form></body></html>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;using System.Data.SqlClient;public partial class Default2 : System.Web.UI.Page, System.Web.UI.ICallbackEventHandler{ protected void Page_Load(object sender, EventArgs e) { if (!this.IsPostBack) { this.DropDownList1.DataSource = this.SqlDataSource1; this.DropDownList1.DataTextField = "au_lname"; this.DropDownList1.DataValueField = "au_id"; this.DropDownList1.DataBind(); this.DropDownList1.Attributes.Add("onchange", "GetOrders(this.options[this.selectedIndex].value,'bbbbb');"); } } protected String callBack { get { return this.ClientScript.GetCallbackEventReference(this, "arg", "ClientCallback", "context"); } } public string RaiseCallbackEvent(string eventArgument) { DataSet ds = new DataSet(); SqlConnection cnn=new SqlConnection ("Data Source=JKDL-PORTAL;Initial Catalog=pubs;Persist Security Info=True;User ID=sa;Password=111" ); SqlDataAdapter da = new SqlDataAdapter("select titles.title_id,title from titles inner join titleauthor on titleauthor.title_id = titles.title_id where au_id = '" + eventArgument + "'", cnn); cnn.Open (); da.Fill(ds); System.Text.StringBuilder str = new System.Text.StringBuilder(); foreach (DataRow dr in ds.Tables[0].Rows) { str.Append(dr["title"]); str.Append("|"); } return str.ToString (); } }呵..... 越来越好了....
参考
http://www.extremeexperts.com/Net/Articles/ClientCallbacksinASPNETWhidbey.aspx