<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>  
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">  
<html>  
  <head>  
    <title>My JSP 'index.jsp' starting page</title>  
    <meta http-equiv="pragma" content="no-cache">  
    <meta http-equiv="cache-control" content="no-cache">  
    <meta http-equiv="expires" content="0">      
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">  
    <meta http-equiv="description" content="This is my page">  
    <script type="text/
javascript" src="
include/js/jquery.js"></script>  
    <script type="text/javascript">  
    $(function(){  
        $("#city").change(function(){  
            $.getJSON("option",{index:$(this).val()},function(myJSON){  
                var myOptions="";  
                for(var i=0;i<myJSON.length;i++){  
                    myOptions += '<option value="' + myJSON[i].optionValue + '">' + myJSON[i].optionDisplay +   
                    '</option>';  
                }  
                $("#area").empty();  
                $("#area").html(myOptions);  
            });  
        });  
        $("#city").change();  
    })  
    </script>  
  </head>  
  <body>  
    This is my JSP page. <br>  
    <select id="city">   
        <option value="1">北京</option>  
        <option value="2">上海</option>  
        <option value="3">天津</option>  
    </select>  
    <select id="area">  
    </select>  
  </body>  
</html> 
package cn.h
linuxjishu/13830.html target=_blank class=infotextkey>awk.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 Option extends HttpServlet {  
  
    public void doGet(HttpServletRequest request, HttpServletResponse response)  
            throws ServletException, IOException {  
        response.setContentType("text/xml");  
        response.setHeader("Cache-Control", "no-cache");  
        response.setContentType("text/html; charset=utf-8");   
        String JSON_text = "";  
        String city = (String) request.getParameter("index");  
        System.out.println("城市号:"+city);  
        if(city.equals("1")){  
            JSON_text = "[{optionValue:'011',optionDisplay:'海淀区'},{optionValue:'012',optionDisplay:'东城区'},{optionValue:'013',optionDisplay:'西城区'}]";  
        }else if(city.equals("2")){  
            JSON_text = "[{optionValue:'21',optionDisplay:'闵行区'},{optionValue:'22',optionDisplay:'宝山区'},{optionValue:'23',optionDisplay:'浦东区'}]";  
        }else if(city.equals("3")){  
            JSON_text = "[{optionValue:'31',optionDisplay:'和平区'},{optionValue:'32',optionDisplay:'南开区'},{optionValue:'33',optionDisplay:'塘沽区'}]";  
        }  
          
        PrintWriter out = null;  
        try{  
            out = response.getWriter();  
        } catch (IOException ex) {  
            ex.printStackTrace();  
        }  
        out.write(JSON_text);  
        out.close();  
    }  
  
    public void doPost(HttpServletRequest request, HttpServletResponse response)  
            throws ServletException, IOException {  
  
        doGet(request, response);  
    }  
  
}