AJAX完成三级级下拉联动【省份-城市-区域】-阿里云开发者社区

AJAX应用案例--基于mysql，以POST方式，用DOM对象，完成三级级下拉联动【省份-城市-区域】，效果图如下：

数据库如下：

省份城市区域

Jsp页面代码：

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<%@ page language="java" pageEncoding="UTF-8"%>  

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">  

<html>  

  <body>  

    <select id="provinceID">  

        <option>请选择省份</option>  

        <option value="1">广东</option>  

        <option value="2">湖南</option>  

    </select>  

    <select id="cityID">  

        <option>请选择城市</option>  

    </select>  

    <select id="areaID">  

        <option>请选择区域</option>  

    </select>  

    <script type="text/javascript">  

        function createAJAX(){  

            var ajax = null;  

            try{  

                ajax = new ActiveXObject("microsoft.xmlhttp");  

            }catch(e){  

                try{  

                    ajax = new XMLHttpRequest();  

                }catch(e){  

                    alert("请更换浏览器");  

                }  

            }  

            return ajax;  

        }  

    </script>  

    <script type="text/javascript">  

        //创建AJAX引擎对象  

        var ajax = createAJAX();  

        //产生事件  

        document.getElementById("provinceID").onchange = function(){  

                //再次选择省份时，清空city下拉框  

              //定位city下拉框  

              var citySelectElement = document.getElementById("cityID");  

              var optionElementArray = citySelectElement.options;  

              var size = optionElementArray.length;  

              if(size>1){  

                for(var i=size-1;i>0;i--){  

                    citySelectElement.removeChild(optionElementArray[i]);  

                }  

              }  

              //再次选择省份时，清空area下拉框  

               //定位area下拉框  

              var areaSelectElement = document.getElementById("areaID");  

              var areaOptionArray = areaSelectElement.options;  

              var size = areaOptionArray.length;  

              if(size>1){  

                for(var i=size-1;i>0;i--){  

                    areaSelectElement.removeChild(areaOptionArray[i]);  

                }  

              }  

              //获取选中省份的编号  

              var optionElement = this[this.selectedIndex];   

              var provinceId = optionElement.value;  

              //准备发送请求  

              var method = "POST";  

              var url = "${pageContext.request.contextPath}/ProvinceCityAreaServlet?id="+new Date().getTime();  

              ajax.open(method,url);  

              //设置以POST表单形式发送，自动将请求体的中文进行编码    

              ajax.setRequestHeader("content-type","application/x-www-form-urlencoded");      

              //真正发送请求体中的数据  

              var content = "provinceId="+provinceId + "&method=provinceToCity";  

              ajax.send(content);  

              //监听服务端的响应  

              ajax.onreadystatechange = function(){  

                if(ajax.readyState==4){  

                    if(ajax.status==200){  

                        var jsonJavaString = ajax.responseText;  

                        //jsonJavaString = [{"name":"长沙"},{"name":"湘潭"},{"name":"株洲"}]  

                        var json = eval("("+jsonJavaString+")");  

                        //返回值，就是可解析并执行的JavaScript代码  

                        //json = [{"name":"长沙"},{"name":"湘潭"},{"name":"株洲"}]  

                        var size = json.length;  

                        //迭代  

                        for(var i=0;i<size;i++){  

                            var city = json[i].name;  

                            var cid = json[i].id;  

                            //创建option节点  

                            var optionElement = document.createElement("option");  

                            //设置option节点之间的内容  

                            optionElement.innerHTML = city;  

                            optionElement.setAttribute("value",cid);  

                            //添加到city下拉框中  

                            citySelectElement.appendChild(optionElement);  

                        }  

                    }  

                }  

              };  

        };  

        //===============================cityToArea==================================================  

        //产生事件  

        document.getElementById("cityID").onchange = function(){  

              //再次选择城市时，定位area下拉框，清空area下拉框  

              var areaSelectElement = document.getElementById("areaID");  

              var areaOptionArray = areaSelectElement.options;  

              var size = areaOptionArray.length;  

              if(size>1){  

                for(var i=size-1;i>0;i--){  

                    areaSelectElement.removeChild(areaOptionArray[i]);  

                }  

              }  

              //获取选中城市的编号  

              var optionElement = this[this.selectedIndex];   

              var cid = optionElement.value;  

              //准备发送请求  

              var method = "POST";  

              var url = "${pageContext.request.contextPath}/ProvinceCityAreaServlet?id="+new Date().getTime();  

              ajax.open(method,url);  

              //设置以POST表单形式发送，自动将请求体的中文进行编码    

              ajax.setRequestHeader("content-type","application/x-www-form-urlencoded");      

              //真正发送请求体中的数据  

              var content = "cid="+cid + "&method=cityToArea";  

              ajax.send(content);  

              //监听服务端的响应  

              ajax.onreadystatechange = function(){  

                if(ajax.readyState==4){  

                    if(ajax.status==200){  

                        var jsonJavaString = ajax.responseText;  

                        //jsonJavaString = [{"name":"长沙"},{"name":"湘潭"},{"name":"株洲"}]  

                        var json = eval("("+jsonJavaString+")");  

                        //返回值，就是可解析并执行的JavaScript代码  

                        //json = [{"name":"长沙"},{"name":"湘潭"},{"name":"株洲"}]  

                        var size = json.length;  

                        //迭代  

                        for(var i=0;i<size;i++){  

                            var area = json[i].name;  

                            //var cid = json[i].name;  

                            //创建option节点  

                            var optionElement = document.createElement("option");  

                            //设置option节点之间的内容  

                            optionElement.innerHTML = area;  

                            //optionElement.setAttribute("id",cid);  

                            //添加到city下拉框中  

                            areaSelectElement.appendChild(optionElement);  

                        }  

                    }  

                }  

              };  

        };  

    </script>  

  </body>  

</html>

servlet代码：

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package kerwin.servlet;  

import java.io.IOException;  

import java.io.PrintWriter;  

import java.util.List;  

import javax.servlet.ServletException;  

import javax.servlet.http.HttpServlet;  

import javax.servlet.http.HttpServletRequest;  

import javax.servlet.http.HttpServletResponse;  

import kerwin.bean.Area;  

import kerwin.bean.City;  

import kerwin.service.ProvinceCityAreaService;  

import net.sf.json.JSONArray;  

import net.sf.json.JsonConfig;  

public class ProvinceCityAreaServlet extends HttpServlet {  

    ProvinceCityAreaService service = new ProvinceCityAreaService();  

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  

        request.setCharacterEncoding("utf-8");  

        String method = request.getParameter("method");  

        if("provinceToCity".equals(method)){  

            this.ProvinceToCity(request, response);  

        }else if("cityToArea".equals(method)){  

            this.cityToArea(request, response);  

        }  

    }  

    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  

        doGet(request, response);  

    }  

    public void ProvinceToCity(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  

        response.setContentType("text/html; charset=utf-8");  

        PrintWriter out = response.getWriter();  

        List<City> citys = null;  

        //获取参数  

        String pid = request.getParameter("provinceId");  

        try {  

            citys = service.findAllCityByProvince(pid);   

            //使用第三方工具类，将对象转成JSON格式的字符串  

            JsonConfig config = new JsonConfig();  

            //去掉不需要的参数  

            //config.setExcludes(new String[]{"id"});  

            //将citys转换为json格式的字符串  

            JSONArray jsonArray = JSONArray.fromObject(citys, config);  

            String jsonJavaStr = jsonArray.toString();  

            //将字符串响应给ajax引擎  

            out.write(jsonJavaStr);  

        } catch (Exception e) {  

            e.printStackTrace();  

        }  

    }  

    public void cityToArea(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  

        response.setContentType("text/html; charset=utf-8");  

        PrintWriter out = response.getWriter();  

        List<Area> areas = null;  

        //获取参数  

        String cid = request.getParameter("cid");  

        try {  

            areas = service.findAllAreaByProvince(cid);   

            //使用第三方工具类，将对象转成JSON格式的字符串  

            JsonConfig config = new JsonConfig();  

            //去掉不需要的参数  

            config.setExcludes(new String[]{"id"});  

            //将citys转换为json格式的字符串  

            JSONArray jsonArray = JSONArray.fromObject(areas, config);  

            String jsonJavaStr = jsonArray.toString();  

            //将字符串响应给ajax引擎  

            out.write(jsonJavaStr);  

        } catch (Exception e) {  

            e.printStackTrace();  

        }  

    }  

}

service层代码：省略.....

DAO层代码：

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package kerwin.dao;  

import java.util.List;  

import org.apache.commons.dbutils.QueryRunner;  

import org.apache.commons.dbutils.handlers.BeanListHandler;  

import kerwin.bean.Area;  

import kerwin.bean.City;  

import kerwin.utils.JdbcUtil;  

public class ProvinceCityAreaDao{  

    public List<City> findAllCityByProvince(String pid)  throws Exception{  

        List<City> citys = null;  

        QueryRunner runner = new QueryRunner(JdbcUtil.dataSource);  

        String sql = "select * from citys where pid = ?";  

        Object params[]={pid};  

        citys = runner.query(sql, new BeanListHandler<City>(City.class), params);  

        return citys;  

    }  

    public List<Area> findAllAreaByProvince(String cid)  throws Exception{  

        List<Area> areas = null;  

        QueryRunner runner = new QueryRunner(JdbcUtil.dataSource);  

        String sql = "select * from area where cid = ?";  

        Object params[]={cid};  

        areas = runner.query(sql, new BeanListHandler<Area>(Area.class), params);  

        return areas;  

    }  

}

还有三个province、city、area JavaBean类省略......

mysql连接使用c3p0连接池：

c3p0-config.xml：

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<?xml version="1.0" encoding="UTF-8"?>  

<c3p0-config>  

    <default-config>  

        <property name="driverClass">com.mysql.jdbc.Driver</property>  

        <property name="jdbcUrl">jdbc:mysql://127.0.0.1:3306/ajax</property>  

        <property name="user">root</property>  

        <property name="password">root</property>  

        <property name="acquireIncrement">2</property>  

        <property name="initialPoolSize">5</property>  

        <property name="minPoolSize">1</property>  

        <property name="maxPoolSize">5</property>  

    </default-config>  

</c3p0-config>

JdbcUtil.java：

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package kerwin.utils;  

import com.mchange.v2.c3p0.ComboPooledDataSource;  

public class JdbcUtil {  

    public static ComboPooledDataSource dataSource = new ComboPooledDataSource();  

    public static ComboPooledDataSource getDataSource() {  

        return dataSource;  

    }  

}