Ajax实现省市县三级联动

import java.util.List;public interface ProvinceDao { List<Province> findAll();}

import java.util.List;public interface CityDao { List<City> findCityByPid(int pid);}

import java.util.List;public interface AreaDao { List<Area> findAreaByCid(int cid);}

import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.util.ArrayList;import java.util.List;public class ProvinceDaoImpl implements ProvinceDao{ public List<Province> findAll(){ Connection conn = DBHelper.getConn(); ArrayList<Province> provinces = new ArrayList<Province>(); String sql = "select * from aprovince"; try { PreparedStatement ps = conn.prepareStatement(sql); ResultSet rs = ps.executeQuery(); while (rs.next()){ Province p = new Province(); p.setPid(rs.getInt(1)); p.setPname(rs.getString(2)); provinces.add(p); } } catch (SQLException e) { e.printStackTrace(); } return provinces; }}

import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.util.ArrayList;import java.util.List;public class CityDaoImpl implements CityDao { @Override public List<City> findCityByPid(int pid) { Connection conn = DBHelper.getConn(); ArrayList<City> cities = new ArrayList<>(); String sql = "select * from acity where pid=?"; try { PreparedStatement ps = conn.prepareStatement(sql); ps.setInt(1,pid); ResultSet rs = ps.executeQuery(); while (rs.next()){ City city = new City(); city.setPid(rs.getInt(3)); city.setCid(rs.getInt(1)); city.setCname(rs.getString(2)); cities.add(city); } } catch (SQLException e) { e.printStackTrace(); } return cities; }}

import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.util.ArrayList;import java.util.List;public class AreaDaoImpl implements AreaDao { @Override public List<Area> findAreaByCid(int cid) { Connection conn = DBHelper.getConn(); ArrayList<Area> areas = new ArrayList<>(); String sql = "select * from aarea where cid=?"; try { PreparedStatement ps = conn.prepareStatement(sql); ps.setInt(1,cid); ResultSet rs = ps.executeQuery(); while (rs.next()){ Area area = new Area(); area.setCid(rs.getInt(3)); area.setAid(rs.getInt(1)); area.setAname(rs.getString(2)); areas.add(area); } } catch (SQLException e) { e.printStackTrace(); } return areas; }}

package cn.zhc.servlet;import cn.zhc.dao.Impl.ProvinceDaoImpl;import cn.zhc.dao.ProvinceDao;import cn.zhc.domin.Province;import com.alibaba.fastjson.JSONObject;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;import java.util.List;@WebServlet("/findAll")public class FindAll extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("utf-8"); response.setContentType("text/html;charset=utf-8"); ProvinceDao provinceDao = new ProvinceDaoImpl(); List<Province> lists=provinceDao.findAll(); response.getWriter().write(JSONObject.toJSONString(lists)); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); }}

package cn.zhc.servlet;import cn.zhc.dao.CityDao;import cn.zhc.dao.Impl.CityDaoImpl;import cn.zhc.domin.City;import com.alibaba.fastjson.JSONObject;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;import java.util.List;@WebServlet("/findCityByPid")public class FindCityByPid extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("utf-8"); response.setContentType("text/html;charset=utf-8"); String pid = request.getParameter("pid"); CityDao cityDao = new CityDaoImpl(); List<City> cityList = cityDao.findCityByPid(Integer.parseInt(pid)); response.getWriter().write(JSONObject.toJSONString(cityList)); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); }}

package cn.zhc.servlet;import cn.zhc.dao.AreaDao;import cn.zhc.dao.Impl.AreaDaoImpl;import cn.zhc.domin.Area;import com.alibaba.fastjson.JSONObject;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;import java.util.List;@WebServlet("/findAreaByCid")public class FindAreaByCid extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("utf-8"); response.setContentType("text/html;charset=utf-8"); String cid = request.getParameter("cid"); AreaDao areaDao = new AreaDaoImpl(); List<Area> areas = areaDao.findAreaByCid(Integer.parseInt(cid)); response.getWriter().write(JSONObject.toJSONString(areas)); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); }}

<%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head> <title>三级联动</title> <script type="text/javascript" src="js/jquery-1.8.3.js"></script></head><body><script type="text/javascript"> $(function () { $.ajax({ type:"get", url:"findAll", dataType:"json", success:function (data) { var obj=$("#province"); for(var i=0;i<data.length;i++){ var ob="<option value='"+data[i].pid+"'>"+data[i].pname+"</option>"; obj.append(ob); } } }) $("#province").change(function () { $("#city option").remove(); $.ajax({ type:"get", async:false, url:"findCityByPid?pid="+$("#province").val(), dataType:"json", success:function (data) { var obj=$("#city"); for(var i=0;i<data.length;i++){ var ob="<option value='"+data[i].cid+"'>"+data[i].cname+"</option>"; obj.append(ob); } } }) }); $("#city,#province").change(function () { $("#area option").remove(); $.ajax({ type:"get", async:false, url:"findAreaByCid?cid="+$("#city").val(), dataType:"json", success:function (data) { var obj=$("#area"); for(var i=0;i<data.length;i++){ var ob="<option value='"+data[i].aid+"'>"+data[i].aname+"</option>"; obj.append(ob); } } }) }); });</script><select name="province" id="province"> <option value="0">请选择</option></select>省<select name="city" id="city"> <option value="0">请选择</option></select>市<select name="area" id="area"> <option value="0">请选择</option></select>县</body></html>