ASP.NET

http://www.cnblogs.com/Mac_Hui/archive/2010/07/27/1785864.html

1、首先建立以个.ashx文件（Generic Handler）,在此文件中生成JSON数据。

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;

    }

}

2、其次在前台调用ashx文件中生成的数据

<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>

这样就OK了。

   注意：

         1、要调试ashx代码，需要安装VS2005 SP1,即使有sp2也不可以的。

  　　 2、Dropdownlist增加空白选项是：$("<option></option>").val("").html("").appendTo("#DropDownList1")；