Asp.net+jquery How to realize the two-level linkage function of the provinces and municipalities

This article mainly introduces the method of implementing the two-level linkage function of the city and the jquery+asp.net, involving the operation skills of the ASP.

This paper describes the method of realizing the two-level linkage function of jquery+asp.net. Share to everyone for your reference, as follows:

Page HTML:

<%@ page language= "C #" autoeventwireup= "true" codefile= "DdlAjax.aspx.cs" inherits= "Threeajaxdrop_ddlajax"%> <! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd ">
asp:

(1) Default.aspx.cs

public partial class threeajaxdrop_default:system.web.ui.page{  protected void Page_Load (object sender, EventArgs E  {    String sql = "Select * from Province";    String strtemp = "\" text\ ": \" {0}\ ", \" value\ ": \" {1}\ ""; Construct the format string {"text": "Beijing", "value": "00001"}    StringBuilder sb = new StringBuilder ();    OleDbDataReader reader = oledbhelper.executereader (sql);    while (reader. Read ())    {      string str1 = string. Format (strtemp, reader["province"]. ToString (), reader["Provinceid"]. ToString ());      Sb. Append ("{" +str1+ "},");    }    Reader. Close ();    String json = sb. ToString ();    Response.Write ("[" +json. Substring (0,json. LENGTH-1) + "]");}  }
(2) Handlerdropdownajax.ashx

public class Handlerdropdownajax:ihttphandler {public void ProcessRequest (HttpContext context) {if (context. request.querystring["type"]! = NULL && context. request.querystring["FID"] = null) {String type = context. request.querystring["type"]. ToString (); Mainly used to identify whether the query city or the area table string fid = context. request.querystring["FID"].   ToString ();      The parent ID of the city or region String sql = "SELECT * from" + type + "where father= '" + FID + "'"; Construct the type of data [{"Text": "Nanchang", "Value": "0001"},{"text": "Shangrao", "Value": "0002"}]//string strtemp = "{\" text\ ": \" {0}\ ", \" value \ ": \" {1}\ "}";//A mistake has been made here: the direct construction will be wrong, because the curly braces are formatted with curly braces, the parsing will be error string strtemp = "\" text\ ": \" {0}\ ", \" value\ ": \" {1}\ "";      Construct the format string {"text": "Beijing", "value": "00001"} StringBuilder sb = new StringBuilder ();      OleDbDataReader reader = oledbhelper.executereader (SQL); while (reader. Read ()) {string str1 = string. Format (strtemp, reader[2]. ToString (), reader[1].        ToString ()); Sb. Append ("{" + str1 + "},"); The curly braces on both sides are formatted and added} reader.      Close (); String json = sb.      ToString (); Context. Response.Write ("[" + JSON. Substring (0, JSON. LENGTH-1) + "]");    The function of substring is to remove the last ' comma '} public bool IsReusable {get {return false; }  }}