Ajax实现省市县三级联动（ajax级联查询）学会了吗

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文章摘要

本文介绍了使用Ajax实现省市县三级联动的具体技术方案。文章首先定义了三个数据库接口：`ProvinceDao`、`CityDao` 和 `AreaDao`，用于分别管理省份、市和县的数据。接着，通过Java Spring框架实现了这三个接口的后端服务，包括`ProvinceDaoImpl`、`CityDaoImpl`和`AreaDaoImpl`，这些类使用JDBC连接数据库并实现相应的方法，通过JDBC语句动态获取数据。此外，文章还展示了Servlet实现部分，包括省、市、县三个层级的Servlet，使用`JSESSIONaviest`处理AJAX请求，并通过JSP页面提供了用户交互界面，允许用户选择省份、市或县，并通过AJAX调用后端服务获取数据并展示在下一级下拉框中。整体来看，文章通过分层设计和动态数据获取，实现了省市县三级联动的高效管理。

本文实例为大家分享了Ajax实现省市县三级联动的具体代码，供大家参考，具体内容如下

首先建立数据库，如下所示

接口

省

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

市

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

县

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

接口实现类

省

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;
}
}

市

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;
}
}

县

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;
}
}

servlet

省

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);
}
}

市

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;

@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);
}
}

县

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;

@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);
}
}

JSP页面

<%@ page contentType=”text/html;charset=UTF-8″ language=”java” %>
<html>
<head>
<title>三级联动</title>
<script type=”text/javascript” src=”https://www.jb51.net/article/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>