- 论坛徽章:
- 0
|
级联菜单在web项目中经常我们会用到,现在大概有这么2中思路,
用javascript 脚本将要级联的数据做成一个数组,在选择第一级的时候,级联第2级的数据。这种在数据量不大,关系不是很复杂时很管用。
运用Ajax的异步访问。
js部分:
var XMLHttpReq;
var currentSort;
//创建XMLHttpRequest对象
function createXMLHttpRequest() {
if(window.XMLHttpRequest) { //Mozilla 浏览器
XMLHttpReq = new XMLHttpRequest();
}
else if (window.ActiveXObject) { // IE浏览器
try {
XMLHttpReq = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
try {
XMLHttpReq = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {}
}
}
}
//发送请求函数
function sendRequest(url) {
createXMLHttpRequest();
XMLHttpReq.open("GET", url, true);
XMLHttpReq.onreadystatechange = processResponse;//指定响应函数
XMLHttpReq.send(null); // 发送请求
}
// 处理返回信息函数
function processResponse() {
if (XMLHttpReq.readyState == 4) { // 判断对象状态
if (XMLHttpReq.status == 200) { // 信息已经成功返回,开始处理信息
updateMenu();
} else { //页面不正常
alert(XMLHttpReq.status+"您所请求的页面有异常。");
}
}
}
//更新菜单函数
function updateMenu() {
var res=XMLHttpReq.responseXML.getElementsByTagName("res")
/**下面是用innerHTML输出控件内容的一般用法**/
//var subMenu = "";
//for(var i = 0; i res.length; i++) {
// subMenu = subMenu + " " + res.firstChild.data + "";
//}
//currentSort.innerHTML = subMenu;
var list = document.all.list;
list.options.length=0;
list.add(new Option("---请选择---",""));
for(var i=0;ires.length;i++){
list.add(new Option(res.firstChild.data,res.firstChild.data));
}
}
// 创建级联菜单函数
function showSubMenu(obj) {
//currentSort =document.getElementById(obj);
//currentSort.parentNode.style.display = "";
sendRequest("/LQweb/MenuAjaxServlet?id=" + obj);
/**下面这一句的作用是:每次选择后回到第一个选项**/
//document.all.mli.options[0].selected=true;
}
jsp文件部分:
jsp:useBean id="depts"
class="com.mei.DataToGetDepts">/jsp:useBean>部门:select
onchange="showSubMenu(this.options[this.options.selectedIndex].value)"
name="mli" style="width:150px">
option value=''>---请选择---/option>
c:forEach var="item" items="${depts.depts}">
option value="${item.id}">${item.department }/option>
/c:forEach>
/select>
br />
姓名:select name="list" id="list2" onchange="this.location()"
style="width:150px">
option name="">---请选择---/option>
/select>
servlet部分:
package com.mei;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.hibernate.Session;
import org.hibernate.criterion.Expression;
import com.mei.hibernate.HDept;
import com.mei.hibernate.HUser;
import com.mei.hibernate.HibernateUtil;
/**
* Servlet implementation class for Servlet: MenuAjaxServlet
*
*/
public class MenuAjaxServlet extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet {
/**
*
*/
private static final long serialVersionUID = -3352981617371090766L;
/* (non-Java-doc)
* @see javax.servlet.http.HttpServlet#HttpServlet()
*/
public MenuAjaxServlet() {
super();
}
/* (non-Java-doc)
* @see javax.servlet.http.HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
process(request,response);
}
/* (non-Java-doc)
* @see javax.servlet.http.HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
process(request,response);
}
private void process(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{
String str=request.getParameter("id");
Integer id=new Integer(str);
HibernateUtil.beginTransaction();
Session session=HibernateUtil.getSession();
HDept dept=(HDept) session.load(HDept.class, id);
List list=session.createCriteria(HUser.class).add(Expression.eq("department",dept)).list();
Iterator it=list.iterator();
response.setContentType("text/xml; charset=UTF-8");
response.setHeader("Cache-Control", "no-cache");
ServletOutputStream out= response.getOutputStream();
out.println("");
while(it.hasNext()){
HUser user=(HUser)it.next();
out.println(""+user.getName()+"");
}
out.println("");
out.close();
}
}
本文来自ChinaUnix博客,如果查看原文请点:http://blog.chinaunix.net/u2/63956/showart_717948.html |
|