Ajax实现省市三级联动V1.1

这是一个Servlet应用。。

该版本用到了Json-lib工具包，关于Json-lib的使用，请参见我的博文

http://blog.csdn.net/jadyer/archive/2011/02/01/6171659.aspx

首先是web.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
	<servlet>
		<servlet-name>InitProvinceServlet</servlet-name>
		<servlet-class>com.jadyer.servlet.InitProvinceServlet</servlet-class>
	</servlet>
	<servlet>
		<servlet-name>GetCityServlet</servlet-name>
		<servlet-class>com.jadyer.servlet.GetCityServlet</servlet-class>
	</servlet>
	<servlet>
		<servlet-name>GetAreaServlet</servlet-name>
		<servlet-class>com.jadyer.servlet.GetAreaServlet</servlet-class>
	</servlet>

	<servlet-mapping>
		<servlet-name>InitProvinceServlet</servlet-name>
		<url-pattern>/servlet/InitProvinceServlet</url-pattern>
	</servlet-mapping>
	<servlet-mapping>
		<servlet-name>GetCityServlet</servlet-name>
		<url-pattern>/servlet/GetCityServlet</url-pattern>
	</servlet-mapping>
	<servlet-mapping>
		<servlet-name>GetAreaServlet</servlet-name>
		<url-pattern>/servlet/GetAreaServlet</url-pattern>
	</servlet-mapping>

	<!-- 在version="2.5"中，可以直接在<welcome-file-list>里执行Servlet应用 -->
	<welcome-file-list>
		<welcome-file>servlet/InitProvinceServlet</welcome-file>
	</welcome-file-list>
</web-app>

然后是用来显示省市三级联动效果的index.jsp页面

<%@ page language="java" pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<style>
#area {
	background-color: #FFFFC0;
	font-size: 12px;
	color: green;
}
</style>
<script type="text/javascript">
	var xmlHTTP = new XMLHttpRequest(); //支持Internet Explorer-8.0.6001.18702

	function getCitys(provinceID){
		//若省份项选中了【==请选择省份==】则清空城市列表数据，并显示【==请选择城市==】
		if('0' == provinceID){
			clearCitys();
			return;
		}
		xmlHTTP.open('GET', '${pageContext.request.contextPath}/servlet/GetCityServlet?provinceID='+provinceID, true);
		xmlHTTP.onreadystatechange = callbackCitys; //设置回调函数
		xmlHTTP.setRequestHeader("if-Modified-Since", "0"); //设置不使用浏览器缓存
		xmlHTTP.send(null); //发送请求
	}

	function callbackCitys(){
		if(4==xmlHTTP.readyState && 200==xmlHTTP.status){
			//此时返回的数据类似于【[{"areas":[],"cityID":4,"cityName":"哈尔滨","description":"著名的冰城","parentID":0},{"areas":[],"cityID":5,"cityName":"佳木斯","description":"传说的贼城","parentID":0},{"areas":[],"cityID":6,"cityName":"双鸭山","description":"满族发源地","parentID":0}]】
			var citys = eval(xmlHTTP.responseText);
			clearCitys();
			var city = document.getElementById("city");
			for(var i=0; i<citys.length; i++){
				city.options[i+1] = new Option(citys[i].cityName, citys[i].cityID); //new Option(text,value)
			}
		}
	}

	//清空城市列表数据
	function clearCitys(){
		var city = document.getElementById('city');
		document.getElementById("area").innerHTML = "";
		city.length = 0;
		city.options[0] = new Option('==请选择城市==', '0');
	}
	
	function getArea(cityID){
		if('0' == cityID){
			document.getElementById("area").innerHTML = "";
			return;
		}
		xmlHTTP.open('GET', '${pageContext.request.contextPath}/servlet/GetAreaServlet?cityID='+cityID, true);
		xmlHTTP.onreadystatechange = callbackArea;
		xmlHTTP.setRequestHeader("if-Modified-Since", "0");
		xmlHTTP.send(null);
	}
	
	function callbackArea(){
		if(4==xmlHTTP.readyState && 200==xmlHTTP.status){
			//此时返回的数据类似于【{"areas":[{"areas":[],"cityID":13,"cityName":"巴彦县","description":"我的家乡","parentID":0},{"areas":[],"cityID":14,"cityName":"延寿县","description":"延寿山庄","parentID":0},{"areas":[],"cityID":15,"cityName":"木兰县","description":"慈航古寺","parentID":0}],"cityID":4,"cityName":"哈尔滨","description":"著名的冰城","parentID":0}】
			var city = eval('(' + xmlHTTP.responseText + ')');
			var msg = "<p><b>" + city.cityName +"市为：" + city.description + "</b><br/>";
			if(0 == city.areas.length){
				msg += "没有区县";
			}else{
				msg += "其下有" + city.areas.length + "个区县，依次为：<br/>";
				var areas = city.areas;
				for(var i=0; i<areas.length; i++){
					msg += ("名称：" + areas[i].cityName + "&nbsp;&nbsp;&nbsp;&nbsp;描述：" + areas[i].description + "<br/>");
				}
			}
			msg += "</p>";
			document.getElementById("area").innerHTML = msg;
		}
	}
</script>

省份：
<select id="province" onchange="getCitys(this.value)">
	<option value="0">==请选择省份==</option>
	<c:forEach items="${requestScope.provinces}" var="province">
		<option value="${province.cityID}">${province.cityName}</option>
	</c:forEach>
</select>

城市：
<select id="city" onchange="getArea(this.value)">
	<option>==请选择城市==</option>
</select>
<div id="area"></div>

然后是用于从数据库执行查询操作的CityDao.java

package com.jadyer.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;

import com.jadyer.model.City;

/**
 * 这里的代码，应该重构一下，但为了演示方便，就没有重构
 */
public class CityDao {
	/**
	 * 根据父ID得到所有一级子类
	 * @see 如果传递为0，则得到所有根节点
	 */
	public List<City> findByParentID(int parentID){
		String sql = "select cityID, cityName, description from city where parentID=?";
		List<City> citys = new ArrayList<City>();
		try {
			Context context = new InitialContext();
			//有关jdbc/oracleds连接池的配置，参见http://blog.csdn.net/jadyer/archive/2010/11/10/6001023.aspx
			DataSource ds = (DataSource)context.lookup("java:/comp/env/jdbc/oracleds");  
			Connection conn = ds.getConnection();
			PreparedStatement pstmt = conn.prepareStatement(sql);
			pstmt.setInt(1, parentID);
			ResultSet rs = pstmt.executeQuery();
			while(rs.next()){
				citys.add(new City(rs.getInt("cityID"), rs.getString("cityName"), rs.getString("description")));
			}
		} catch (NamingException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return citys;
	}
	
	/**
	 * 根据ID得到该城市的详细信息
	 */
	public City fingByCityID(int cityID){
		String sql = "select cityName, description from city where cityID=?";
		City city = null;
		try {
			Context context = new InitialContext();  
			DataSource ds = (DataSource)context.lookup("java:/comp/env/jdbc/oracleds");  
			Connection conn = ds.getConnection();
			PreparedStatement pstmt = conn.prepareStatement(sql);
			pstmt.setInt(1, cityID);
			ResultSet rs = pstmt.executeQuery();
			while(rs.next()){
				city = new City(cityID, rs.getString("cityName"), rs.getString("description"));
			}
		} catch (NamingException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return city;
	}
}

用于储存City信息的实体类

package com.jadyer.model;

import java.util.List;

public class City {
	private Integer parentID;
	private Integer cityID;
	private String cityName;
	private String description;
	private List<City> areas; //新增。。用于储存该城市下所有区县的详细信息
	
	/* 五个属性的getter和setter方法略 */
	
	public City(){}
	
	public City(Integer cityID, String cityName, String description){
		this.cityID = cityID;
		this.cityName = cityName;
		this.description = description;
	}
}

用于初始化所有省份信息的InitProvinceServlet.java

package com.jadyer.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.jadyer.dao.CityDao;

@SuppressWarnings("serial")
public class InitProvinceServlet extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		CityDao cityDao = new CityDao();
		//获取所有省份的信息
		request.setAttribute("provinces", cityDao.findByParentID(0));
		request.getRequestDispatcher("/index.jsp").forward(request, response);
	}
}

用于获取指定省份下的所有城市信息的GetCityServlet.java

package com.jadyer.servlet;

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.sf.json.JSONArray;

import com.jadyer.dao.CityDao;
import com.jadyer.model.City;

@SuppressWarnings("serial")
public class GetCityServlet extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		response.setContentType("text/html; charset=UTF-8");
		int provinceID = Integer.parseInt(request.getParameter("provinceID"));
		CityDao cityDao = new CityDao();
		//返回该省份下的所有城市的信息
		List<City> citys = cityDao.findByParentID(provinceID);
		JSONArray jsonObject = JSONArray.fromObject(citys);
		response.getWriter().println(jsonObject.toString());
	}
}

用于获取指定城市下的所有区县信息的GetAreaServlet.java

package com.jadyer.servlet;

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.sf.json.JSONObject;

import com.jadyer.dao.CityDao;
import com.jadyer.model.City;

@SuppressWarnings("serial")
public class GetAreaServlet extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		response.setContentType("text/html; charset=UTF-8");
		int cityID = Integer.parseInt(request.getParameter("cityID"));
		CityDao cityDao = new CityDao();
		//得到该城市下所有区县的详细信息的集合
		List<City> areas = cityDao.findByParentID(cityID);
		//得到当前城市的详细信息
		City city22 = cityDao.fingByCityID(cityID);
		city22.setAreas(areas);
		JSONObject jsonObject = JSONObject.fromObject(city22);
		response.getWriter().println(jsonObject.toString());
	}
}

最后是数据库脚本文件

--Oracle 11g
--创建表格
create table city(
	id number(3) primary key,
	parentID number(3), --0表示根节点
	cityID number(3),
	cityName varchar(20),
	description varchar(20)
)

--创建序列
create sequence city_sequence increment by 1 start with 1 nomaxvalue nocycle;

--添加一级菜单
insert into city values(city_sequence.nextval, 0, 1, '黑龙江', '东北三省的黑龙江省');
insert into city values(city_sequence.nextval, 0, 2, '吉林省', '东北三省的吉林省');
insert into city values(city_sequence.nextval, 0, 3, '辽宁省', '东北三省的辽宁省');
--添加二级菜单
insert into city values(city_sequence.nextval, 1, 4, '哈尔滨', '著名的冰城');
insert into city values(city_sequence.nextval, 1, 5, '佳木斯', '传说的贼城');
insert into city values(city_sequence.nextval, 1, 6, '双鸭山', '满族发源地');
insert into city values(city_sequence.nextval, 2, 7, '长春', '中国汽车之都');
insert into city values(city_sequence.nextval, 2, 8, '辽源', '中国琵琶之乡');
insert into city values(city_sequence.nextval, 2, 9, '通化', '中国医药之城');
insert into city values(city_sequence.nextval, 3, 10, '沈阳', '中国优秀旅游城市');
insert into city values(city_sequence.nextval, 3, 11, '大连', '中国第一海军广场');
insert into city values(city_sequence.nextval, 3, 12, '铁岭', '中国小品王的家乡');
--添加三级菜单
--这里只提供了黑龙江省的三级联动数据，关于其它省份的数据，请自行添加
insert into city values(city_sequence.nextval, 4, 13, '巴彦县', '我的家乡');
insert into city values(city_sequence.nextval, 4, 14, '延寿县', '延寿山庄');
insert into city values(city_sequence.nextval, 4, 15, '木兰县', '慈航古寺');
insert into city values(city_sequence.nextval, 5, 16, '抚远县', '白四爷庙');
insert into city values(city_sequence.nextval, 5, 17, '汤原县', '西郎君城');
insert into city values(city_sequence.nextval, 5, 18, '桦川县', '鱼米之乡');
insert into city values(city_sequence.nextval, 6, 19, '集贤县', '大菩提寺');
insert into city values(city_sequence.nextval, 6, 20, '宝清县', '雁窝之岛');
insert into city values(city_sequence.nextval, 6, 21, '友谊县', '中苏友谊');