ajax实例--responseXML三级联动（未完全实现版）

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



	
		
		
	
	
     
       请选择....
     
	 
	 	请选择.....
	 
  

function ajaxFunction(){
   var xmlHttp;
   try{ // Firefox, Opera 8.0+, Safari
        xmlHttp=new XMLHttpRequest();
    }
    catch (e){
	   try{// Internet Explorer
	         xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
	      }
	    catch (e){
	      try{
	         xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
	      }
	      catch (e){}
	      }
    }
     return xmlHttp;
 }

window.onload = function(){
    //获取XMLHttpRequest对象
	var  xmlRequest=ajaxFunction();
	
	//注册事件
	xmlRequest.onreadystatechange=function(){
		if(xmlRequest.readyState==4){
			if(xmlRequest.status==200||xmlRequest.status==304){
				 var xmlDoc=xmlRequest.responseXML;
				 alert(xmlDoc);
				 /*
				  * 
						
							长春
						
						
							沈阳
						
						
							济南
						
                   	
				  */
				
				 var provinceElements=xmlDoc.getElementsByTagName("province");
				 //alert(provinceElements.length);
				 for(var i=0;i
					       请选择....
					     
					  */
					
					document.getElementById("province").appendChild(optionElement);
					
					
				 }
			}
			
		}
	}
	
	//打开连接
	xmlRequest.open("post","../xmlFileServlet?timeStamp="+new Date().getTime(),true);
	xmlRequest.setRequestHeader("Content-Type","application/x-www-form-urlencoded")
	
	
	//发送请求 
	xmlRequest.send(null);
}

package cn.ajax;

import java.io.IOException;
import java.io.PrintWriter;

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

public class XmlFileServlet extends HttpServlet {

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


	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		//生成一个xml文件
		response.setContentType("text/xml;charset=utf-8");
		PrintWriter out = response.getWriter();
		
		out.println("");
		out.println("");
		out.println("长春");
		out.println("吉林市");
		out.println("四平");
		out.println("松原");
		out.println("通化");
		out.println("");
		
		out.println("");
		out.println("沈阳");
		out.println("大连");
		out.println("鞍山");
		out.println("抚顺");
		out.println("铁岭");
		out.println("");
		
		out.println("");
		out.println("济南");
		out.println("青岛");
		out.println("威海");
		out.println("烟台");
		out.println("潍坊");
		out.println("");
		out.println("");
		
		
	}

}