运用ajax+jsp+servlet实现三级级联菜单

package com.servlet; import java.io.IOException; import java.io.PrintWriter; import java.util.ArrayList; import java.util.List; 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.pojo.City; import com.pojo.Country; public class MenuServlet extends HttpServlet { /** * The doPost method of the servlet. <br> * * This method is called when a form has its tag value method equals to * post. * * @param request * the request send by the client to the server * @param response * the response send by the server to the client * @throws ServletException * if an error occurred * @throws IOException * if an error occurred */ public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=utf-8"); PrintWriter out = response.getWriter(); String uri = request.getRequestURI(); System.out.println("uri:"+uri); String path = uri.substring(uri.lastIndexOf("/"), uri.lastIndexOf(".")); System.out.println("path:" + path); if ("/getCity".equals(path)) { String sheng = request.getParameter("sheng"); System.out.println(sheng); // TO DO // 根据传递过来的省的value值，返回相应的市 if ("gd".equals(sheng)) { // 对象，属性 List<City> city_gd = new ArrayList<City>(); City c0 = new City("shi", "--市--"); City c1 = new City("guangzhou", "广州市"); City c2 = new City("shenzhen", "深圳市"); city_gd.add(c0); city_gd.add(c1); city_gd.add(c2); JSONArray jsonArray = JSONArray.fromObject(city_gd); String jsonStrCity = jsonArray.toString(); System.out.println(jsonStrCity); out.println(jsonStrCity); } else if ("jx".equals(sheng)) { List<City> city_js = new ArrayList<City>(); City c0 = new City("shi", "--市--"); City c1 = new City("nanchang", "南昌市"); City c3 = new City("yichun", "宜春市"); city_js.add(c0); city_js.add(c1); city_js.add(c3); JSONArray jsonArray = JSONArray.fromObject(city_js); String jsonStrCity = jsonArray.toString(); System.out.println(jsonStrCity); out.println(jsonStrCity); } else if ("s".equals(sheng)) { List<City> city_js = new ArrayList<City>(); City c1 = new City("shi", "--市--"); city_js.add(c1); JSONArray jsonArray = JSONArray.fromObject(city_js); String jsonStrCity = jsonArray.toString(); System.out.println(jsonStrCity); out.println(jsonStrCity); } }else if("/getCountry".equals(path)){ String shi = request.getParameter("shi"); System.out.println("shi:"+shi); if("guangzhou".equals(shi)){ List<Country> list = new ArrayList<Country>(); list.add(new Country("qu/xian","--区/县--")); list.add(new Country("haizhuqu","海珠区")); list.add(new Country("tianhequ","天河区")); list.add(new Country("yuexiuqu","越秀区")); list.add(new Country("huaduqu","花都区")); JSONArray jsonArray = JSONArray.fromObject(list); String jsonStr = jsonArray.toString(); out.println(jsonStr); }else if("nanchang".equals(shi)){ List<Country> list = new ArrayList<Country>(); list.add(new Country("qu/xian","--区/县--")); list.add(new Country("haizhuqu","一区")); list.add(new Country("tianhequ","二区")); list.add(new Country("yuexiuqu","三区")); list.add(new Country("huaduqu","四区")); JSONArray jsonArray = JSONArray.fromObject(list); String jsonStr = jsonArray.toString(); out.println(jsonStr); }else if("shenzhen".equals(shi)){ List<Country> list = new ArrayList<Country>(); list.add(new Country("qu/xian","--区/县--")); list.add(new Country("haizhuqu","1区")); list.add(new Country("tianhequ","2区")); list.add(new Country("yuexiuqu","3区")); list.add(new Country("huaduqu","4区")); JSONArray jsonArray = JSONArray.fromObject(list); String jsonStr = jsonArray.toString(); out.println(jsonStr); }else if("yichun".equals(shi)){ List<Country> list = new ArrayList<Country>(); list.add(new Country("qu/xian","--区/县--")); list.add(new Country("haizhuqu","奉新县")); list.add(new Country("tianhequ","高安市")); list.add(new Country("yuexiuqu","万载县")); list.add(new Country("huaduqu","新建县")); JSONArray jsonArray = JSONArray.fromObject(list); String jsonStr = jsonArray.toString(); out.println(jsonStr); }else if("shi".equals(shi)){ List<Country> list = new ArrayList<Country>(); list.add(new Country("qu/xian","--区/县--")); JSONArray jsonArray = JSONArray.fromObject(list); String jsonStr = jsonArray.toString(); out.println(jsonStr); } } } }