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ajax读取数据库内容实现二级联动下拉选择菜单示例

2022-2-5 16:59| 发布者: 菜鸟教程小白| 查看: 261| 评论: 0|原作者: [db:作者]|来自: [db:来源]

摘要: 本文为大家介绍下使用ajax技术读取数据库内容并生成二级联动下拉选择菜单，具体实现如下，感兴趣的朋友可以参考下，希望对大家有所帮助

 
<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"); 
List<MyProcess> 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> 