var createAjax = function(){
  var ajax = null;
  try{
    ajax = new ActiveXObject("microsoft.xmlhttp");
  }catch(e1){
    try{
      ajax = new XMLHttpRequest();
    }catch(e2){
      alert("请换掉你的浏览器");
    }
  }
  return ajax;
}

<%@ page language="Java" contentType="text/html; charset=UTF-8"
  pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>


 
 
    
      
 
 
   
 
 
 
 
     
       请选择省份
       江苏
       江西
     
     
       请选择城市
     
     
 

package com.newtouch.servlet;

import java.io.IOException;

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 SelectServlet
 */
@WebServlet("/SelectServlet")
public class SelectServlet extends HttpServlet {
  private static final long serialVersionUID = 1L;

  /**
   * @see HttpServlet#HttpServlet()
   */
  public SelectServlet() {
    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
    response.getWriter().append("Served at: ").append(request.getContextPath());
  }

  /**
   * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
   *   response)
   */
  protected void doPost(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
    request.setCharacterEncoding("utf-8");
    // 这里是text/xml是把数据放到了xml中
    response.setContentType("text/xml;charset=utf-8");
    String province = request.getParameter("province");
    response.getWriter().write("<?xml version='1.0' encoding='utf-8' ?>");
    response.getWriter().write("");
    if ("江苏".equals(province)) {
      response.getWriter().write("1");
      response.getWriter().write("2");
      response.getWriter().write("3");
      response.getWriter().write("4");
    } else if ("江西".equals(province)) {
      response.getWriter().write("一");
      response.getWriter().write("二");
      response.getWriter().write("三");
      response.getWriter().write("四");
    }
    response.getWriter().write("");
  }

}