This example shares the specific code of java provincial and municipal cascade for your reference. The specific content is as follows
1.LoadAreaServlet.java
package com.scce.servlet; import java.io.IOException;import java.io.PrintWriter;import java.util.ArrayList;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import net.sf.json.JSONArray;import com.scce.pojo.City;import com.scce.pojo.Prov; public class LoadAreaServlet extends HttpServlet { private static final long serialVersionUID = 1L; public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=utf-8"); request.setCharacterEncoding("utf-8"); PrintWriter out = response.getWriter(); ArrayList<Prov> provs = new ArrayList<Prov>(); String provinceID = request.getParameter("provinceID"); if (provinceID=="" || provinceID==null) { System.out.println("Loading prefecture-level city information"); Prov pro1 = new Prov(); pro1.setId(0); pro1.setProvinceName("Hubei"); Prov pro2 = new Prov(); pro2.setId(1); pro2.setProvinceName("Hunan"); Prov pro3 = new Prov(); pro3.setId(2); pro3.setProvinceName("Guangdong"); Prov pro4 = new Prov(); pro4.setId(3); pro4.setProvinceName("Guangxi"); provs.add(pro1); provs.add(pro2); provs.add(pro3); provs.add(pro4); System.out.println(JSONArray.fromObject(provs).toString()); //[{"id":0,"provinceName":"Hubei"},{}] out.print(JSONArray.fromObject(provs).toString()); }else{ ArrayList<City> cities = new ArrayList<City>(); if (provinceID.equals("0")) { City city1 = new City(); city1.setId(0); city1.setCityName("Wuhan City"); City city2 = new City(); city2.setId(1); city2.setCityName("Huangshi City"); City city3 = new City(); city3.setId(2); city3.setCityName("Shiyan City"); citys.add(city1); cities.add(city2); cities.add(city3); } if (provinceID.equals("1")) { City city1 = new City(); city1.setId(0); city1.setCityName("Changsha City"); City city2 = new City(); city2.setId(1); city2.setCityName("Yueyang City"); City city3 = new City(); city3.setId(2); city3.setCityName("Xiangtan City"); cities.add(city1); cities.add(city2); cities.add(city3); } System.out.println(JSONArray.fromObject(citys).toString()); out.print(JSONArray.fromObject(citys).toString()); } } } 2.test1.html
<!DOCTYPE html><html> <head> <title>chapter4-test1</title> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="this is my page"> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <link rel="stylesheet" href="../UI/themes/icon.css" type="text/css"></link> <link rel="stylesheet" href="../UI/themes/default/easyui.css" type="text/css"></link> <!-- <script type="text/javascript" src="../js/jquery-1.8.2.min.js"></script> --> <script type="text/javascript" src="../UI/jquery.min.js"></script> <script type="text/javascript" src="../UI/jquery.easyui.min.js"></script> <script type="text/javascript" src="../UI/jquery.easyui.min.js"></script> <script type="text/javascript" src="../UI/locale/easyui-lang-zh_CN.js"></script> <script type="text/javascript"> //LoadAreaServlet /* var dataCombobox=[{"id":1,"provinceName":"Hubei Province"}, {"id":2,"provinceName":"Hunan Province","selected":true}, {"id":3,"provinceName":"Hebei Province"}, {"id":4,"provinceName":"Henan Province"} ]; */ $(function () { $("#province").combobox({ width: 150, valueField: 'id', //1 textField: 'provinceName', // Hubei Province editable: false, // data:dataCombobox //Specify the data source url for the drop-down list:'../LoadAreaServlet', method:'post', onLoadSuccess:function(data){ var provId = $("#province").combobox("getValue"); loadCity(provId); }, onSelect:function(recode){ loadCity(recode.id); } }); }); function loadCity(provId){ $("#city").combobox({ width: 150, valueField: 'id', //1 textField: 'cityName', // Hubei Province editable: false, // data:dataCombobox //Specify the data source url for the drop-down list:'../LoadAreaServlet?provinceID='+provId, method:'post' }); } </script> </head> <body> Province: <select id="province" > <option value="0">Data is loading..</option> </select> <br/> City: <select id="city" > <option value="">Data is loading..</option> </select> </body></html>The above is all about this article, I hope it will be helpful for everyone to learn Java programming.