该表包括了中国所有的省、市、县、区，它们之间通过parentid关联。
由于每一级的数据都是根据上一级的id查询而来，逻辑十分相似，故我们只需要一个接口就可以完成三级甚至更多级的联动，在这个案例中我们的核心查询就是select * from area where parentid=#{pid}
entity
package com.codeXie.entity; import java.io.Serializable; public class Area implements Serializable { private String areaid; private String areaname; private String parentid; private Integer arealevel; private Integer status; public Area() { } public Area(String areaid, String areaname, String parentid, Integer arealevel, Integer status) { this.areaid = areaid; this.areaname = areaname; this.parentid = parentid; this.arealevel = arealevel; this.status = status; } .......省略了对各属性的set、get }
mapper
public interface AreaMapper { @Select("select * from area where parentid=#{pid}") List<Area> selectMore(Integer pid); }
service
public interface AreaService { List<Area> findCity(int pid); }
servlet
@WebServlet("/AreaServlet") public class AreaServlet extends HttpServlet { @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { resp.setCharacterEncoding("utf-8"); resp.setContentType("text/html;charset=utf-8"); String pid = req.getParameter("pid"); AreaServiceImpl service = new AreaServiceImpl(); List<Area> areas = service.findCity(Integer.parseInt(pid)); String json = new Gson().toJson(areas); resp.getWriter().print(json); } }
三、前端代码<script src="https://www.jb51.net/js/jquery.js"></script> <script> function produceOption(id,list){ console.log(list) $(id).empty() $(list).each((index,item)=>{ $(id).append("<option value="+item.areaid+">"+item.areaname+"</option>") }) } $(()=>{ $.ajax({ url:"AreaServlet", method:"post", data:{pid:0}, dataType:"json", success: function(res) { produceOption("#proviance",res) $("#proviance").prepend("<option selected='selected'>请选择省份</option>") } }) $("#proviance").change(function(){ var pid = $(this).prop("value") $.ajax({ url:"AreaServlet", method:"post", data:{pid:pid}, dataType:"json", success: function(res) { produceOption("#city",res) $("#city").prepend("<option selected='selected'>请选择城市</option>") } }) }) $("#city").on("change",function(){ var pid = $(this).prop("value") $.ajax({ url:"AreaServlet", method:"post", data:{pid:pid}, dataType:"json", success: function(res) { produceOption("#country",res) } }) }) }) </script> </head> <body> <h2>三级联动</h2> <hr/> <select> <option>选择省份</option> </select> <select> <option>选择城市</option> </select> <select> <option>请选择区域</option> </select> </body> </html>