Jquery+jsp to achieve the three-level linkage effect (with source code) of provinces and counties _jquery

This paper illustrates the method of realizing the three-level linkage effect of jquery+jsp in provinces and counties. Share to everyone for your reference, specific as follows:

Here, the MySQL database is used to store all the provinces and counties in the country information (click here to download the source code)

Used jar Packs

Google's Gson.jar
Mysql-connector-java-5.1.13-bin.jar

Post the Experiment diagram:

Display Page index.jsp

<%@ page language= "java" import= "java.util.*" pageencoding= "UTF-8"%> <% String Path = Request.getcontextpath ()
;
String basepath = request.getscheme () + "://" +request.getservername () + ":" +request.getserverport () +path+ "/"; %> <! DOCTYPE HTML PUBLIC "-//w3c//dtd HTML 4.01 transitional//en" >  

Database Interaction Getdropdowndataservlet

public class Getdropdowndataservlet extends HttpServlet {public void doget (HttpServletRequest request, HTTPSERVLETRESPO
 NSE response) throws IOException, servletexception {doPost (request, response);
  public void DoPost (HttpServletRequest request, httpservletresponse response) throws IOException, Servletexception {
  String parentid = Request.getparameter ("ParentID");
  if (ParentID = null | | parentid = = "") {ParentID = "0";
  } Connection conn = null;
  String json = "";
   try {class.forname ("com.mysql.jdbc.Driver");
   conn = Drivermanager.getconnection ("Jdbc:mysql://localhost/dropdown", "root", "root");
   Statement stat = conn.createstatement ();
   ResultSet rs = Stat. executequery ("Select Region_id,region_name from region where parent_id =" + ParentID);
   ArrayList rslist = new ArrayList ();
   Map map = null;
    while (Rs.next ()) {map = new HashMap ();
    Map.put ("id", Rs.getint (1));
    Map.put ("Name", Rs.getstring (2)); Rslist.aDD (map);
   rs = null;
   Gson Gson = new Gson ();
   JSON = Gson.tojson (rslist);
  System.out.println ("json=" + JSON);
  catch (ClassNotFoundException e) {e.printstacktrace ();
  catch (SQLException e) {e.printstacktrace ();
    finally {if (conn!= null) {try {conn.close ();
    catch (SQLException e) {e.printstacktrace ();
  }} response.setcharacterencoding ("UTF-8");
 Response.getwriter (). print (JSON);

 }
}

I hope this article will help you with your jquery programming.