百度搜索指数如何优化关键词搜索排名
需求:网页上选择对应省份之后,动态的关联出该省份对应的市.选择对应的市之后,动态的关联出该市对应的区
关于省市区全国三级Mysql数据：全国省市区三级地区MySQL数据_biubiubiu0706的博客-CSDN博客
页面加载完毕显示所有省份
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>省市区域联动</title>
</head>
<body>
<script type="text/javascript" src="ajax/js/jquery-3.4.1.js"></script>
<script type="text/javascript">$(function (){//页面加载完成//发送ajax请求,获取所有省份.$.ajax({type:"get",url:"/ajax/liandong",data:"f=0",async:true,success:function (data){//[{"code":"001","name":"浙江省"},{"code":"002","name":"陕西省"}]var html="<option value=\"\">--请选择省份--</option>"for(var i=0;i<data.length;i++){var d=data[i];//console.log(d)html+="<option value=\""+d.code+"\">"+d.name+"</option>"}$("#province").html(html)},error:function (){}})//只要change发生,就发送AJAX请求$("#province").change(function(){//alert("this="+this)console.log(this.value)$.ajax({type:"get",url:"/ajax/liandong",data:"f=1&code="+this.value,async:true,success:function (data){//[{"code":"001","name":"浙江省"},{"code":"002","name":"陕西省"}]var html="<option value=\"\">--请选择城市--</option>"for(var i=0;i<data.length;i++){var d=data[i];//console.log(d)html+="<option value=\""+d.code+"\">"+d.name+"</option>"}$("#province1").html(html)},error:function (){}})})$("#province1").change(function(){//alert("this="+this)console.log(this.value)$.ajax({type:"get",url:"/ajax/liandong",data:"f=2&code="+this.value,async:true,success:function (data){//[{"code":"001","name":"浙江省"},{"code":"002","name":"陕西省"}]var html="<option value=\"\">--请选择区域--</option>"for(var i=0;i<data.length;i++){var d=data[i];//console.log(d)html+="<option value=\""+d.code+"\">"+d.name+"</option>"}$("#province2").html(html)},error:function (){}})})})
</script><select id="province">
<!-- <option value="">--请选择省份--</option>-->
<!-- <option value="001">浙江省</option>-->
<!-- <option value="002">陕西省</option>-->
</select>
<select id="province1"></select>
<select id="province2"></select>
</body>
</html>
package com.web;import com.alibaba.fastjson.JSON;
import com.pojo.Area;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.io.PrintWriter;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;/*** @author hrui* @date 2023/9/5 16:08*/
@WebServlet("/liandong")
public class AjaxRequestLiandong extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {String f=req.getParameter("f");String code = req.getParameter("code");Connection conn=null;PreparedStatement ps=null;ResultSet rs=null;List<Area> list=new ArrayList<>();String sql="";try {Class.forName("com.mysql.cj.jdbc.Driver");conn=DriverManager.getConnection("xxx","xxx","xxx");if("0".equals(f)){sql="select id,province_id,province_name from table_china_province";ps= conn.prepareStatement(sql);rs= ps.executeQuery();while(rs.next()){String id=rs.getString("id");String c=rs.getString("province_id");String name=rs.getString("province_name");Area l=new Area(name,c);list.add(l);}}else if("1".equals(f)){sql="select id,city_id,city_name from table_china_city where province_id=?";ps= conn.prepareStatement(sql);ps.setString(1, code);rs= ps.executeQuery();while(rs.next()){String id=rs.getString("id");String c=rs.getString("city_id");String name=rs.getString("city_name");Area l=new Area(name,c);list.add(l);}}else if("2".equals(f)){sql="select id,area_id,area_name from table_china_area where city_id=?";ps= conn.prepareStatement(sql);ps.setString(1, code);rs= ps.executeQuery();while(rs.next()){String id=rs.getString("id");String c=rs.getString("area_id");String name=rs.getString("area_name");Area l=new Area(name,c);list.add(l);}}} catch (ClassNotFoundException | SQLException e) {e.printStackTrace();}finally {if(rs!=null){try {rs.close();} catch (SQLException e) {e.printStackTrace();}}if(ps!=null){try {ps.close();} catch (SQLException e) {e.printStackTrace();}}if(conn!=null){try {conn.close();} catch (SQLException e) {e.printStackTrace();}}}resp.setContentType("text/json;charset=utf-8");PrintWriter writer = resp.getWriter();String s = JSON.toJSONString(list);writer.print(s);}
}