Detailed explanation of Ajax implementation of three-level cascade in provinces and municipalities-PHP Tutorial-php.cn

This article mainly introduces Ajax to realize the three-level cascade of provinces and municipalities. The data comes from the mysql database and has certain reference value. Interested friends can refer to it. I hope it can help everyone.

To implement Ajax to achieve three-level cascading of provinces and municipalities, Java parsing json technology is required
The overall Demo download address is as follows: Click me to download

address.html

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>

 <script type="text/javascript">

  /** 
   * 得到XMLHttpRequest对象 
   */
  function getajaxHttp() {
   var xmlHttp;
   try {
    // Firefox, Opera 8.0+, Safari 
    xmlHttp = new XMLHttpRequest();
   } catch (e) {
    // Internet Explorer 
    try {
     xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
    } catch (e) {
     try {
      xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
     } catch (e) {
      alert("您的浏览器不支持AJAX！");
      return false;
     }
    }
   }
   return xmlHttp;
  }
  /** 
   * 发送ajax请求 
   * url--请求到服务器的URL 
   * methodtype(post/get) 
   * con (true(异步)|false(同步)) 
   * functionName(回调方法名，不需要引号,这里只有成功的时候才调用) 
   * (注意：这方法有二个参数，一个就是xmlhttp,一个就是要处理的对象) 
   */
  function ajaxrequest(url, methodtype, con, functionName) {
   //获取XMLHTTPRequest对象
   var xmlhttp = getajaxHttp();
   //设置回调函数（响应的时候调用的函数）
   xmlhttp.onreadystatechange = function() {
    //这个函数中的代码在什么时候被XMLHTTPRequest对象调用？
    //当服务器响应时，XMLHTTPRequest对象会自动调用该回调方法
    if (xmlhttp.readyState == 4) {
     if (xmlhttp.status == 200) {
      functionName(xmlhttp.responseText);
     }
    }
   };
   //创建请求
   xmlhttp.open(methodtype, url, con);
   //发送请求
   xmlhttp.send();
  }

  window.onload=function(){
   ajaxrequest("addressSerlvet?method=provincial","POST",true,addrResponse);
  }
  //动态获取省的信息
  function addrResponse(responseContents){
   var jsonObj = new Function("return" + responseContents)();
   for(var i = 0; i < jsonObj.addrList.length;i++){
    document.getElementById(&#39;select&#39;).innerHTML += 
     "<option value=&#39;"+jsonObj.addrList[i].id+"&#39;>"
      +jsonObj.addrList[i].address+
     "</option>"
   }
  }
  //选中省后
  function pChange(){
   //先将市的之前的信息清除
   document.getElementById(&#39;selectCity&#39;).innerHTML="<option value=&#39;-1&#39;>请选择市</option>";
   //再将区的信息清除
   document.getElementById(&#39;selectArea&#39;).innerHTML="<option value=&#39;-1&#39;>请选择区</option>";
   //再将用户的输入清楚
   document.getElementById("addr").innerHTML="";
   var val = document.getElementById(&#39;select&#39;).value;
   if(val == -1){
    document.getElementById(&#39;selectCity&#39;)[0].selected = true;
    return;
   }
   //开始执行获取市
   ajaxrequest("addressSerlvet?method=city&provincial="+val,"POST",true,cityResponse);
  }
  //获取市的动态数据
  function cityResponse(responseContents){
   var jsonObj = new Function("return" + responseContents)();
   for(var i = 0; i < jsonObj.cityList.length;i++){
    document.getElementById(&#39;selectCity&#39;).innerHTML += 
     "<option value=&#39;"+jsonObj.cityList[i].id+"&#39;>"
      +jsonObj.cityList[i].address+
     "</option>"
   }
  }
  //选中市以后
  function cChange(){
   var val = document.getElementById(&#39;selectCity&#39;).value;
   //开始执行获取区
   ajaxrequest("addressSerlvet?method=area&cityId="+val,"POST",true,areaResponse);
  }
  //获取区的动态数据
  function areaResponse(responseContents){
   var jsonObj = new Function("return" + responseContents)();
   for(var i = 0; i < jsonObj.areaList.length;i++){
    document.getElementById(&#39;selectArea&#39;).innerHTML += 
     "<option value=&#39;"+jsonObj.areaList[i].id+"&#39;>"
      +jsonObj.areaList[i].address+
     "</option>"
   }
  }
  //点击提交按钮
  function confirM(){
   //获取省的文本值
   var p = document.getElementById("select");
   var pTex = p.options[p.options.selectedIndex].text;
   if(p.value=-1){
    alert("请选择省");
    return;
   }
   //获取市的文本值
   var city = document.getElementById("selectCity");
   var cityTex = city.options[city.options.selectedIndex].text;
   if(city.value=-1){
    alert("请选择市");
    return;
   }
   //获取区的文本值
   var area = document.getElementById("selectArea");
   var areaTex = area.options[area.options.selectedIndex].text;
   if(area.value=-1){
    alert("请选择区");
    return;
   }
   //获取具体位置id文本值
   var addr = document.getElementById("addr").value;
   //打印
   document.getElementById("show").innerHTML = "您选择的地址为 " + pTex + " " + cityTex + " " + areaTex + " " + addr;
  }

 </script>
<body>
 <select id="select" onchange="pChange()">
  <option value="-1">请选择省</option>
 </select>
 <select id="selectCity" onchange="cChange()">
  <option value=&#39;-1&#39;>请选择市</option>
 </select>
 <select id="selectArea" onchange="aChange()">
  <option value=&#39;-1&#39;>请选择市</option>
 </select>
 <input type="text" id="addr" />
 <button onclick="confirM();">确定</button>
 <p id="show"></p>
</body>
</html>

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AddressServlet.java

package cn.bestchance.servlet;

import java.io.IOException;
import java.util.ArrayList;

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 cn.bestchance.dao.AddressDao;
import cn.bestchance.dao.impl.AddressDaoImpl;
import cn.bestchance.entity.Address;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

@WebServlet("/addressSerlvet")
public class AddressSerlvet extends HttpServlet {
 private static final long serialVersionUID = 1L;
 private AddressDao dao = new AddressDaoImpl();

 protected void doGet(HttpServletRequest request,
   HttpServletResponse response) throws ServletException, IOException {
  doPost(request, response);
 }

 /**
  * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
  *  response)
  */
 protected void doPost(HttpServletRequest request,
   HttpServletResponse response) throws ServletException, IOException {

  response.setCharacterEncoding("utf-8");
  response.setContentType("text/html;charset=utf-8");
  String method=request.getParameter("method");
  if("provincial".equals(method)){
   getProvincial(request, response);
  }
  if("city".equals(method)){
   getCity(request, response);
  }
  if("area".equals(method)){
   getArea(request, response);
  }
 }
 /**
  * 根据市id获取该市下的区的全部信息
  * @param request
  * @param response
  * @throws ServletException
  * @throws IOException
  */
 protected void getArea(HttpServletRequest request,
   HttpServletResponse response) throws ServletException, IOException {

  String cityId = request.getParameter("cityId");
  // 从数据库中查询省的信息
  ArrayList<Address> areaList = dao.getAreaByCityId(Integer.parseInt(cityId));
  // 将集合转成json字符串
  JSONObject jsonObj = new JSONObject();
  JSONArray jsonArray = JSONArray.fromObject(areaList);
  jsonObj.put("areaList", jsonArray);
  String jsonDataStr = jsonObj.toString();

  response.getWriter().print(jsonDataStr);
 }
 /**
  * 获取省的信息 并相应
  * @param request
  * @param response
  * @throws ServletException
  * @throws IOException
  */
 protected void getProvincial(HttpServletRequest request,
   HttpServletResponse response) throws ServletException, IOException {

  // 从数据库中查询省的信息
  ArrayList<Address> addrList = dao.getProvince();
  // 将集合转成json字符串
  JSONObject jsonObj = new JSONObject();
  JSONArray jsonArray = JSONArray.fromObject(addrList);
  jsonObj.put("addrList", jsonArray);
  String jsonDataStr = jsonObj.toString();
  response.getWriter().print(jsonDataStr);
 }
 /**
  * 获取市的信息并相应
  * @param request
  * @param response
  * @throws ServletException
  * @throws IOException
  */
 protected void getCity(HttpServletRequest request,
   HttpServletResponse response) throws ServletException, IOException {

  String provinceId = request.getParameter("provincial");
  // 从数据库中查询省的信息
  ArrayList<Address> addrList = dao.getCityByProvinceId(Integer.parseInt(provinceId));

  // 将集合转成json字符串
  JSONObject jsonObj = new JSONObject();
  JSONArray jsonArray = JSONArray.fromObject(addrList);
  jsonObj.put("cityList", jsonArray);
  String jsonDataStr = jsonObj.toString();

  response.getWriter().print(jsonDataStr);
 }

}

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AddressDao.java

package cn.bestchance.dao;

import java.util.ArrayList;

import cn.bestchance.entity.Address;

public interface AddressDao {
 /**
  * 获取省的id和名称
  * @return
  */
 ArrayList<Address> getProvince();
 /**
  * 根据省的id获取市的信息
  * @param provinceId
  * @return
  */
 ArrayList<Address> getCityByProvinceId(int provinceId);
 /**
  * 根据市的id获取区的信息
  * @param cityId
  * @return
  */
 ArrayList<Address> getAreaByCityId(int cityId);
}

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AddressDaoImpl.java

package cn.bestchance.dao.impl;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;

import cn.bestchance.dao.AddressDao;
import cn.bestchance.entity.Address;
import cn.bestchance.util.DBUtil;

public class AddressDaoImpl implements AddressDao {
 private DBUtil db = new DBUtil();
 @Override
 public ArrayList<Address> getProvince() {
  ArrayList<Address> addrList = new ArrayList<Address>();
  db.openConnection();
  String sql = "select * from province";
  ResultSet rs = db.excuteQuery(sql);
  try {
   while(rs.next()){
    Address addr = new Address();
    addr.setId(rs.getInt(2));
    addr.setAddress(rs.getString(3));
    addrList.add(addr);
   }
  } catch (SQLException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }finally{
   if(rs != null){
    try {
     rs.close();
    } catch (SQLException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }
   }
   db.closeResoure();
  }
  return addrList;
 }
 @Override
 public ArrayList<Address> getCityByProvinceId(int provinceId) {
  ArrayList<Address> addrList = new ArrayList<Address>();
  db.openConnection();
  String sql = "select * from city where fatherID = " + provinceId; //431200
  ResultSet rs = db.excuteQuery(sql);
  try {
   while(rs.next()){
    Address addr = new Address();
    addr.setId(rs.getInt(2));
    addr.setAddress(rs.getString(3));
    addrList.add(addr);
   }
  } catch (SQLException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }finally{
   if(rs != null){
    try {
     rs.close();
    } catch (SQLException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }
   }
   db.closeResoure();
  }
  return addrList;
 }
 @Override
 public ArrayList<Address> getAreaByCityId(int cityId) {
  ArrayList<Address> addrList = new ArrayList<Address>();
  db.openConnection();
  String sql = "select * from area where fatherID = " + cityId; //431200
  ResultSet rs = db.excuteQuery(sql);
  try {
   while(rs.next()){
    Address addr = new Address();
    addr.setId(rs.getInt(2));
    addr.setAddress(rs.getString(3));
    addrList.add(addr);
   }
  } catch (SQLException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }finally{
   if(rs != null){
    try {
     rs.close();
    } catch (SQLException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }
   }
   db.closeResoure();
  }
  return addrList;
 }

}

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Entity class Address.java

package cn.bestchance.entity;

public class Address {
 @Override
 public String toString() {
  return "Address [id=" + id + ", address=" + address + "]";
 }
 private int id;
 private String address;
 public int getId() {
  return id;
 }
 public void setId(int id) {
  this.id = id;
 }
 public String getAddress() {
  return address;
 }
 public void setAddress(String address) {
  this.address = address;
 }
 public Address() {
  super();
  // TODO Auto-generated constructor stub
 }
 public Address(int id, String address) {
  super();
  this.id = id;
  this.address = address;
 }

}

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