用ajax技术读取数据库内容实现二级联动下拉选择菜单

来源:互联网 发布:java验证码生成代码 编辑:程序博客网 时间:2024/05/22 09:50
—————————————————————这是ajax(javascript)代码———————————————————————————
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;}
————————————————————————这是客户端表单jsp代码——————————————————————————————
<%@ 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>

————————————————————————这是服务端action代码——————————————————————————————

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

public String getProcessType(){HttpServletRequest request=ServletActionContext.getRequest();String value=request.getParameter("value");List<MyProcess> MyProcesses= processService.getProcessByType(value);for(MyProcess p:MyProcesses){System.out.println(p.getName());}request.setAttribute("list",MyProcesses);return SUCCESS;}
————————————————————————这是服务端jsp代码——————————————————————————————
<%@ 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>


这个过程差不多就这些!


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