使用Ajax实现三级联动

首先准备数据库只有一张表

分析数据库根据 parentid来查

jsp代码 servlet代码

<%--

  Created by IntelliJ IDEA.

  User: 60590

  Date: 2019/12/4

  Time: 20:26

  To change this template use File | Settings | File Templates.

--%>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<html>

<head>

    <title>Title</title>

    <base href=<%= request.getContextPath()%>/>

    <script src="js/jquery-1.9.1.js"></script>

    <script>
        //当页面加载时执行change1方法来获取省 使用jq中的ajax 简洁方式

       function change1() {

           $.post("servlet/AreaServlet","id=0",function (result) {
               //遍历集合

               for (var i in result){
                  //获取标签 append 可以识别标签
                  $("#pro").append("<option value='"+result[i].areaid+"'>"+result[i].areaname+"</option>")

               }

           },"json");

       }
        //当省改变时 执行此方法 并且把当前省的value传进来

       function change2(val) {

           $.post("servlet/AreaServlet","id="+val,function (result) {

               $("#city").html("<option>--请选择--</option>");

               for (var i in result){

                   $("#city").append("<option value='"+result[i].areaid+"'>"+result[i].areaname+"</option>")

               }

           },"json");

       }
        //当市改变时  执行此方法

       function change3(val) {

           $.post("servlet/AreaServlet","id="+val,function (result) {

               $("#con").html("<option>--请选择--</option>");

               for (var i in result){

                   $("#con").append("<option value='"+result[i].areaid+"'>"+result[i].areaname+"</option>")

               }

           },"json");

       }

    </script>

</head>

<body onload="change1()">

省:<select id="pro" onchange="change2(this.value)">

    <option>---请选择---</option>

</select>

市:<select id="city" onchange="change3(this.value)">

    <option>---请选择---</option>

</select>

县:<select id="con">

    <option>---请选择---</option>

</select>

</body>

</html>

package com.bjsxt.servlet;

import com.bjsxt.entity.Area;

import com.bjsxt.serviceIml.AreaServiceIml;

import com.google.gson.Gson;

import org.apache.ibatis.annotations.Select;

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;

/**

 * @program: JavaEE

 * @description

 * @author: wuhao

 * @create: 2019-12-04 20:22

 **/

@WebServlet("/servlet/AreaServlet")

public class AreaServlet extends HttpServlet {

    @Override

    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        resp.setContentType("text/html;charset=UTF-8");

        //接受参数

        String id = req.getParameter("id");

        int i = Integer.parseInt(id);

        //处理参数

        AreaServiceIml areaServiceIml = new AreaServiceIml();

        List<Area> list = areaServiceIml.findAll(i);

        //转换为json 格式  需要导入Gson的jar包

        Gson gson = new Gson();

        String s = gson.toJson(list);

        resp.getWriter().print(s);

    }

}

巴特西

使用Ajax实现三级联动

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