using System;
using System.Web;
using System.Data;
using System.Text;public class EmployeeLoad : IHttpHandler {public void ProcessRequest (HttpContext context) {StringBuilder sb = new StringBuilder();DataTable dt = new DataTable();dt = FetchEmployeeInfo().Tables[0];if (dt == null)return;if (dt.Rows.Count == 0){return;}else{           sb.Append("[");         for(int i=0;i<dt.Rows.Count;i++){sb.Append("{\"ID\":\"" + dt.Rows[i]["ID"].ToString() + "\",\"Name\":\"" + dt.Rows[i]["Name"].ToString() + "\",\"Age\":" + dt.Rows[i]["Age"].ToString() + ",\"Tel\":\"" + dt.Rows[i]["Tel"].ToString() + "\"},");}sb.Remove(sb.Length - 1, 1);sb.Append("]");}context.Response.ContentType = "application/json";context.Response.ContentEncoding = Encoding.UTF8;context.Response.Write(sb.ToString());}public bool IsReusable {get {return false;}}public DataSet FetchEmployeeInfo(){DataSet ds = new DataSet();DataTable dt = new DataTable();dt.Columns.Add("ID", typeof(string));dt.Columns.Add("Name", typeof(string));dt.Columns.Add("Age", typeof(int));dt.Columns.Add("Tel", typeof(string));//DataRow dr;
DataRow dr = dt.NewRow();dr["ID"] = "1111";dr["Name"] = "Jim Hui";dr["Age"] = 29;dr["Tel"] = "15962557701";dt.Rows.Add(dr);dr = dt.NewRow();dr["ID"] = "2222";dr["Name"] = "Kevin Lee";dr["Age"] = 35;dr["Tel"] = "15962557702";dt.Rows.Add(dr);ds.Tables.Add(dt);return ds;}}

<script type="text/javascript" src="JavaScript/jquery-1.3.2.js"></script><script language="javascript" type="text/javascript">$(document).ready(function(){BindDropDownList();       });function  BindDropDownList(){$("#DropDownList1").html("");                     $.getJSON("EmployeeLoad.ashx",null,function(json){$.each(json,function(i){$("#DropDownList1").append($("<option></option>").val(json[i].ID).html(json[i].Name))});});$("<option></option>").val("").html("").appendTo("#DropDownList1");}</script>