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数据加载中……

Ajax实现二级联动菜单

index.jsp:
<%@ page language="java" pageEncoding="UTF-8"%>
<html>
    
<head>
        
<title>二级菜单联动演示</title>
        
<script type="text/javascript">
    
var req;
    window.onload
=function()
    
{//页面加载时的函数
    }

    
    
function Change_Select(){//当第一个下拉框的选项发生改变时调用该函数
      var province = document.getElementById('province').value;
      
var url = "select?id="+ escape(province);
      
if(window.XMLHttpRequest){
        req 
= new XMLHttpRequest();
      }
else if(window.ActiveXObject){
        req 
= new ActiveXObject("Microsoft.XMLHTTP");
      }

      
if(req){
        req.open(
"GET",url,true);
         
//指定回调函数为callback
        req.onreadystatechange = callback;
        req.send(
null);
      }

    }

    
//回调函数
    function callback(){
      
if(req.readyState ==4){
        
if(req.status ==200){
          parseMessage();
//解析XML文档
        }
else{
          alert(
"不能得到描述信息:" + req.statusText);
        }

      }

    }

    
//解析返回xml的方法
    function parseMessage(){
      
var xmlDoc = req.responseXML.documentElement;//获得返回的XML文档
      var xSel = xmlDoc.getElementsByTagName('select');
      
//获得XML文档中的所有<select>标记
      var select_root = document.getElementById('city');
      
//获得网页中的第二个下拉框
      select_root.options.length=0;
      
//每次获得新的数据的时候先把每二个下拉框架的长度清0
      
      
for(var i=0;i<xSel.length;i++){
        
var xValue = xSel[i].childNodes[0].firstChild.nodeValue;
        
//获得每个<select>标记中的第一个标记的值,也就是<value>标记的值
        var xText = xSel[i].childNodes[1].firstChild.nodeValue;
        
//获得每个<select>标记中的第二个标记的值,也就是<text>标记的值
        
        
var option = new Option(xText, xValue);
        
//根据每组value和text标记的值创建一个option对象
        
        
try{
          select_root.add(option);
//将option对象添加到第二个下拉框中
        }
catch(e){
        }

      }

    }
        
  
</script>
    
</head>

    
<body>
        
<div align="center">
            
<form name="form1" method="post" action="">
                
<table width="70%" border="0" cellspacing="0" cellpadding="0">
                    
<tr>
                        
<td align="center">
                            二级联动示例
                        
</td>
                    
</tr>
                    
<tr>
                        
<td>
                            
<select name="province" id="province" onChange="Change_Select()">
                                
<!--第一个下拉菜单-->
                                
<option value="0">
                                    请选择
                                
</option>
                                
<option value="1">
                                    北京
                                
</option>
                                
<option value="2">
                                    天津
                                
</option>
                                
<option value="3">
                                    山东
                                
</option>
                            
</select>
                            
<select name="city" id="city">
                                
<!--第二个下拉菜单-->
                                
<option value="0">
                                    请选择
                                
</option>
                            
</select>
                        
</td>
                    
</tr>
                    
<tr>
                        
<td>
                        
</td>
                    
<tr>
                
</table>
            
</form>
        
</div>
    
</body>
</html>

SelectServlet:
package com;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/***
 * 
 * 
@author zdw
 *
 
*/

public class SelectServlet extends HttpServlet
{

    
private static final long serialVersionUID = 1L;

    
public SelectServlet()
    
{
        
super();
    }


    
public void destroy()
    
{
        
super.destroy();
    }


    
public void doGet(HttpServletRequest request, HttpServletResponse response)
            
throws ServletException, IOException
    
{
//        response.setCharacterEncoding("GBK");
        response.setContentType("text/xml");
        response.setHeader(
"Cache-Control""no-cache");
        request.setCharacterEncoding(
"GBK");
        response.setCharacterEncoding(
"UTF-8");
        String targetId 
= request.getParameter("id").toString();
        System.out.println(targetId);
        
// 获得请求中参数为id的值
        String xml_start = "<selects>";
        String xml_end 
= "</selects>";
        String xml 
= "";

        
if (targetId.equalsIgnoreCase("0"))
        
{
            xml 
= "<select><value>0</value><text>请选择</text></select>";
        }
 else if (targetId.equalsIgnoreCase("1"))
        
{
            xml 
= "<select><value>1</value><text>昌平</text></select>";
            xml 
+= "<select><value>2</value><text>丰台</text></select>";
            xml 
+= "<select><value>3</value><text>海淀</text></select>";
            xml 
+= "<select><value>4</value><text>朝阳</text></select>";
        }
 else if (targetId.equalsIgnoreCase("2"))
        
{
            xml 
= "<select><value>1</value><text>塘沽区</text></select>";
            xml 
+= "<select><value>2</value><text>汉沽区</text></select>";
            xml 
+= "<select><value>3</value><text>大港区</text></select>";
            xml 
+= "<select><value>4</value><text>东丽区</text></select>";
        }
 else
        
{// 如果是3,则返回下面的字符
            xml = "<select><value>1</value><text>济南</text></select>";
            xml 
+= "<select><value>2</value><text>青岛</text></select>";
            xml 
+= "<select><value>3</value><text>淄博</text></select>";
            xml 
+= "<select><value>4</value><text>枣庄</text></select>";
        }


        String last_xml 
= xml_start + xml + xml_end;
        response.getWriter().write(last_xml);

    }


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


    
public void init() throws ServletException
    
{
    }


}


web.xml:
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"
    xmlns:xsi
="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation
="http://java.sun.com/xml/ns/j2ee 
    http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
>
    
<servlet>
        
<servlet-name>SelectServlet</servlet-name>
        
<servlet-class>com.SelectServlet</servlet-class>
    
</servlet>

    
<servlet-mapping>
        
<servlet-name>SelectServlet</servlet-name>
        
<url-pattern>/select</url-pattern>
    
</servlet-mapping>
    
<welcome-file-list>
        
<welcome-file>index.jsp</welcome-file>
    
</welcome-file-list>
</web-app>
源码下载


posted on 2008-05-29 09:12 々上善若水々 阅读(11328) 评论(3)  编辑  收藏 所属分类: AJAX

评论

# re: Ajax实现二级联动菜单[未登录]  回复  更多评论   

呵呵,纯手写。
不用Ajax框架。不错!
2008-05-30 17:56 |

# re: Ajax实现二级联动菜单  回复  更多评论   

哥们,你这从Servlet里返回的数据是乱码呀
2008-08-27 21:06 | 麦田守望者

# re: Ajax实现二级联动菜单  回复  更多评论   

你试过了吗?这个例子在我这运行并不乱码。
2008-08-29 07:00 | 々上善若水々

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