ajax读取数据库内容实现二级联动下拉选择菜单示例

PRE class=javascript name="code">/PRE>PRE class=javascript name="code">—————————————————————这是ajax（javascript）代码———————————————————————————/PRE>PRE class=javascript name="code">/PRE>PRE class=javascript name="code">function send_request(callback, urladdress, isReturnData){
var xmlhttp = getXMLHttpRequest();
xmlhttp.onreadystatechange = function(){
if (xmlhttp.readyState == 4) {//readystate 为4即数据传输结束
try{
if(xmlhttp.status == 200){
if(isReturnData isReturnData==true){
callback(xmlhttp.responseText);
}
}else{
callback("抱歉，没找到此页面:"+ urladdress +"");
}
} catch(e){
callback("抱歉，发送请求失败，请重试 " + e);
}
}
}
xmlhttp.open("POST", urladdress, true);
xmlhttp.send(null);
}
function getXMLHttpRequest() {
var xmlhttp;
if (window.XMLHttpRequest) {
try {
xmlhttp = new XMLHttpRequest();
xmlhttp.overrideMimeType("text/html;charset=UTF-8");//设定以UTF-8编码识别数据
} catch (e) {}
} else if (window.ActiveXObject) {
try {
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {
try {
xmlhttp = new ActiveXObject("Msxml2.XMLHttp");
} catch (e) {
try {
xmlhttp = new ActiveXObject("Msxml3.XMLHttp");
} catch (e) {}
}
}
}
return xmlhttp;
}
/PRE>————————————————————————这是客户端表单jsp代码——————————————————————————————BR>
%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>%@ taglib uri="/struts-tags" prefix="s"%>!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">html>head>meta http-equiv="Content-Type"
content="text/html; charset=UTF-8">title>Insert title here/title>script type="text/javascript" src="%=request.getContextPath()%>/js/xmlhttp.js">/script>script type="text/javascript">function getProcess(value) {var process = document.getElementById('process');send_request(function(value2)
{process.innerHTML = value2;}, "getProcessType.action?value="+value, true);}/script>/head>body>div>form action="" method="post" name="form">select name="process" onchange="getProcess(this.value)">option value="0" selected>请选择流程种类/option>option value="Y">业务流程/option>option
value="G">管理流程/option>option value="Z">支持流程/option>/select>div id="process">select name="smallclass">option value="一级流程名称" selected>请选择一级流程名称/OPTION>/select>/div>input type="submit" value="提交">/form>/div>/body>/html>
PRE>/PRE>
BR>
P>PRE class=html name="code">PRE class=html name="code">————————————————————————这是服务端action代码——————————————————————————————/PRE>BR>
P>/P>
PRE>/PRE>
这里是我的业务逻辑，每个逻辑不同，所以这段代码这只是为了把想要显示的内容放在request范围内，然后return到下一个页面.javabean中有我的MyProcess类和它的属性
P>/P>
P>PRE class=java name="code">public String getProcessType(){
HttpServletRequest request=ServletActionContext.getRequest();
String value=request.getParameter("value");
ListMyProcess> MyProcesses= processService.getProcessByType(value);
for(MyProcess p:MyProcesses){
System.out.println(p.getName());
}
request.setAttribute("list",MyProcesses);
return SUCCESS;
}/PRE>PRE class=html name="code">/PRE>PRE class=html name="code">/PRE>PRE class=html name="code">————————————————————————这是服务端jsp代码——————————————————————————————/PRE>PRE class=html name="code">%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
%@ include file="/page/share/taglib.jsp"%>
!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
html>
head>
meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
title>Insert title here/title>
/head>
body>
select name="smallclass">
option value="一级流程名称" selected>请选择一级流程名称/OPTION>
c:forEach items="${list}" var="myprocess">
option value="${myprocess.processID}" >
${myprocess.name}
/option>
/c:forEach>
/select>
/body>
/html>/PRE>BR>
BR>
P>/P>
P>这个过程差不多就这些！/P>
P>BR>
/P>
/PRE>