Ajax常用实例（级联下拉列表）

index.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script language="javascript" src="JS/AjaxRequest.js"></script>
<script language="javascript">
//获取省份和直辖市
function getProvince(){
	var loader=new net.AjaxRequest("ZoneServlet?action=getProvince&nocache="+new Date().getTime(),deal_getProvince,onerror,"GET");
}
function deal_getProvince(){
	provinceArr=this.req.responseText.split(",");	//将获取的省份名称字符串分隔为数组
	
	for(i=0;i<provinceArr.length;i++){		//通过循环将数组中的省份名称添加到下拉列表中
		//Option是 select 中的选择项,str1 是页面中看到的描述,而str2是这一项的值
		document.getElementById("province").options[i]=new Option(provinceArr[i],provinceArr[i]);
	}
	if(provinceArr[0]!=""){
		getCity(provinceArr[0]);	//获取市县
	}
}

//在页面载入后显示默认的省份
window.onload=function(){
	 getProvince();		//获取省份和直辖市
}
/*************************************************************************************************************/
//获取市县
function getCity(selProvince){
	var loader=new net.AjaxRequest("ZoneServlet?action=getCity&parProvince="+selProvince+"&nocache="+new Date().getTime(),deal_getCity,onerror,"GET");
}
function deal_getCity(){
	cityArr=this.req.responseText.split(",");	//将获取的市县名称字符串分隔为数组
	document.getElementById("city").length=0;	//清空下拉列表
	for(i=0;i<cityArr.length;i++){		//通过循环将数组中的市县名称添加到下拉列表中
		document.getElementById("city").options[i]=new Option(cityArr[i],cityArr[i]);
	}
}
function onerror(){}		//错误处理函数
</script>
  </head>
  
  <body style="font-size: 9pt;">
  请选择：
  		<!-- onchange 事件在用户改变输入域的内容时执行 JavaScript 代码 -->
	  <select name="province" id="province" onChange="getCity(this.value)">
      </select>
      -
	  <select name="city" id="city">
	  </select>
  </body>
</html>

CityMap.jsp

package com.wgh.tools;

import java.util.LinkedHashMap;
import java.util.Map;

public class CityMap {
	   /**
     *  全国（省，直辖市，自治区，特别行政区）映射集合
     */
    public static Map<String,String[]> model=new LinkedHashMap();
    static{
        model.put("北京", new String[]{"北京"});
        model.put("上海", new String[]{"上海"});
        model.put("天津", new String[]{"天津"});
        model.put("重庆", new String[]{"重庆"});
        model.put("黑龙江", new String[]{"哈尔滨","齐齐哈尔","牡丹江","大庆","伊春","双鸭山","鹤岗","鸡西","佳木斯","七台河","黑河","绥化","大兴安岭"});
        model.put("吉林", new String[]{"长春","延边","吉林","白山","白城","四平","松原","辽源","大安","通化"});
        model.put("辽宁", new String[]{"沈阳","大连","葫芦岛","旅顺","本溪","抚顺","铁岭","辽阳","营口","阜新","朝阳","锦州","丹东","鞍山"});
        model.put("内蒙古", new String[]{"呼和浩特","呼伦贝尔","锡林浩特","包头","赤峰","海拉尔","乌海","鄂尔多斯","通辽"});
        model.put("河北", new String[]{"石家庄","唐山","张家口","廊坊","邢台","邯郸","沧州","衡水","承德","保定","秦皇岛"});
        model.put("河南", new String[]{"郑州","开封","洛阳","平顶山","焦作","鹤壁","新乡","安阳","濮阳","许昌","漯河","三门峡","南阳","商丘","信阳","周口","驻马店"});
        model.put("山东", new String[]{"济南","青岛","淄博","威海","曲阜","临沂","烟台","枣庄","聊城","济宁","菏泽","泰安","日照","东营","德州","滨州","莱芜","潍坊"});
        model.put("山西", new String[]{"太原","阳泉","晋城","晋中","临汾","运城","长治","朔州","忻州","大同","吕梁"});
        model.put("江苏", new String[]{"南京","苏州","昆山","南通","太仓","吴县","徐州","宜兴","镇江","淮安","常熟","盐城","泰州","无锡","连云港","扬州","常州","宿迁"});
        model.put("安徽", new String[]{"合肥","巢湖","蚌埠","安庆","六安","滁州","马鞍山","阜阳","宣城","铜陵","淮北","芜湖","毫州","宿州","淮南","池州"});
        model.put("陕西", new String[]{"西安","韩城","安康","汉中","宝鸡","咸阳","榆林","渭南","商洛","铜川","延安"});
        model.put("宁夏", new String[]{"银川","固原","中卫","石嘴山","吴忠"});
        model.put("甘肃", new String[]{"兰州","白银","庆阳","酒泉","天水","武威","张掖","甘南","临夏","平凉","定西","金昌"});
        model.put("青海", new String[]{"西宁","海北","海西","黄南","果洛","玉树","海东","海南"});
        model.put("湖北", new String[]{"武汉","宜昌","黄冈","恩施","荆州","神农架","十堰","咸宁","襄樊","孝感","随州","黄石","荆门","鄂州"});
        model.put("湖南", new String[]{"长沙","邵阳","常德","郴州","吉首","株洲","娄底","湘潭","益阳","永州","岳阳","衡阳","怀化","韶山","张家界"});
        model.put("浙江", new String[]{"杭州","湖州","金华","宁波","丽水","绍兴","雁荡山","衢州","嘉兴","台州","舟山","温州"});
        model.put("江西", new String[]{"南昌","萍乡","九江","上饶","抚州","吉安","鹰潭","宜春","新余","景德镇","赣州"});
        model.put("福建", new String[]{"福州","厦门","龙岩","南平","宁德","莆田","泉州","三明","漳州"});
        model.put("贵州", new String[]{"贵阳","安顺","赤水","遵义","铜仁","六盘水","毕节","凯里","都匀"});
        model.put("四川", new String[]{"成都","泸州","内江","凉山","阿坝","巴中","广元","乐山","绵阳","德阳","攀枝花","雅安","宜宾","自贡","甘孜州","达州","资阳","广安","遂宁","眉山","南充"});
        model.put("广东", new String[]{"广州","深圳","潮州","韶关","湛江","惠州","清远","东莞","江门","茂名","肇庆","汕尾","河源","揭阳","梅州","中山","德庆","阳江","云浮","珠海","汕头","佛山"});
        model.put("广西", new String[]{"南宁","桂林","阳朔","柳州","梧州","玉林","桂平","贺州","钦州","贵港","防城港","百色","北海","河池","来宾","崇左"});
        model.put("云南", new String[]{"昆明","保山","楚雄","德宏","红河","临沧","怒江","曲靖","思茅","文山","玉溪","昭通","丽江","大理"});
        model.put("海南", new String[]{"海口","三亚","儋州","琼山","通什","文昌"});
        model.put("新疆", new String[]{"乌鲁木齐","阿勒泰","阿克苏","昌吉","哈密","和田","喀什","克拉玛依","石河子","塔城","库尔勒","吐鲁番","伊宁"});
    }  
}

ZoneServlet.java

package com.wgh.tools;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

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

/**
 * Servlet implementation class ZoneServlet
 */
@WebServlet("/ZoneServlet")
public class ZoneServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public ZoneServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		String action=request.getParameter("action");		//获取action参数的值
		if("getProvince".equals(action)){	//获取省份和直辖市信息
			this.getProvince(request,response);
		}else if("getCity".equals(action)){	//获取市县信息
			this.getCity(request, response);
		}
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

	public void getProvince(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		response.setCharacterEncoding("GBK");		//设置响应的编码方式
		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		
		String result="";
		CityMap cityMap=new CityMap();//实例化保存省份信息的CityMap类的实例
		Map<String,String[]> map= cityMap.model;//获取省份信息保存到Map中
		Set<String> set=map.keySet();		//获取Map集合中的键，并以Set集合返回
		Iterator it=set.iterator();
		while(it.hasNext()){		//将获取的省份连接为一个以逗号分隔的字符串
			result=result+it.next()+",";
		}
		result=result.substring(0, result.length()-1);	//去除最后一个逗号
		
		out.print(result);		//输出获取的省份字符串
		out.flush();
		out.close();
	}
	/**
	 * 获取市县
	 * @param request
	 * @param response
	 * @throws ServletException
	 * @throws IOException
	 */
	public void getCity(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		response.setCharacterEncoding("GBK");	//设置响应的编码方式
		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		
		String result="";
		String selProvince=request.getParameter("parProvince");	//获取选择的省份
		selProvince=new String(selProvince.getBytes("ISO-8859-1"),"GBK");
		CityMap cityMap=new CityMap();	//实例化保存省份信息的CityMap类的实例
		Map<String,String[]> map=cityMap.model;	//获取省份信息保存到Map中
		String[]arrCity= map.get(selProvince);	//获取指定键的值
		for(int i=0;i<arrCity.length;i++){		//将获取的市县连接为一个以逗号分隔的字符串
			result=result+arrCity[i]+",";
		}
		result=result.substring(0, result.length()-1);	//去除最后一个逗号
		
		out.print(result);								//输出获取的市县字符串
		out.flush();
		out.close();
	}
}

Ajax重构：AjaxRequest.js

var net = new Object(); // 定义一个全局变量net
// 编写构造函数
net.AjaxRequest = function(url, onload, onerror, method, params) {
	this.req = null;
	this.onload = onload;
	this.onerror = (onerror) ? onerror : this.defaultError;
	this.loadDate(url, method, params);
}
// 编写用于初始化XMLHttpRequest对象并指定处理函数，最后发送HTTP请求的方法
net.AjaxRequest.prototype.loadDate = function(url, method, params) {
	if (!method) {
		method = "GET";
	}
	if (window.XMLHttpRequest) {
		this.req = new XMLHttpRequest();
	} else if (window.ActiveXObject) {
		this.req = new ActiveXObject("Microsoft.XMLHTTP");
	}
	if (this.req) {
		try {
			var loader = this;
			this.req.onreadystatechange = function() {
				net.AjaxRequest.onReadyState.call(loader);
			}
			this.req.open(method, url, true);// 建立对服务器的调用
			if (method == "POST") {// 如果提交方式为POST
				this.req.setRequestHeader("Content-Type",
						"application/x-www-form-urlencoded"); // 设置请求头
			}
			this.req.send(params); // 发送请求
		} catch (err) {
			this.onerror.call(this);
		}
	}
}

// 重构回调函数
net.AjaxRequest.onReadyState = function() {
	var req = this.req;
	var ready = req.readyState;
	if (ready == 4) {// 请求完成
		if (req.status == 200) {// 请求成功
			this.onload.call(this);
		} else {
			this.onerror.call(this);
		}
	}
}
// 重构默认的错误处理函数
net.AjaxRequest.prototype.defaultError = function() {
	alert("错误数据\n\n回调状态:" + this.req.readyState + "\n状态: " + this.req.status);
}

Ajax常用实例（级联下拉列表）

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