已经做好的代码，下拉的控制

<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">

    <title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">

  </head>

  <body>
   <form action="form" method="post">
  <table>
   <tr>
  <td>
<select id="sel" onChange="chg()" >
<option value="1" >1</option>
<option value="2">2</option>
<option value="3">3</option>
</select>
</td>
   </tr>
   <tr>
   <td><input type="text"  id ="apid" name="apid" value="1"/></td><td><input type="text"  id ="apid" name="apid" value="2"/></td><td><input type="text"  id ="apid" name="apid" value="3"/></td>
   </tr>
   </table>
   </form>
  </body>
  <script type="text/javascript">
var mycars = new Array()
alert (mycars.length);
mycars[0] = "Saab"
mycars[1] = "Volvo"
mycars[2] = "BMW"
if(mycars.length == 3) {
alert (mycars.length);
var sel=document.getElementById('sel');
var option=sel.options[sel.selectedIndex = 0];
document.getElementsByName("apid")[0].value="46";
}

if(document.getElementById("sel").value=="1"){
document.getElementsByName("apid")[1].style.display="none";
document.getElementsByName("apid")[2].style.display="none";
} else if (document.getElementById("sel").value=="2") {
document.getElementsByName("apid")[2].style.display="none";
}

   function chg(){
if(document.getElementById("sel").value=="1"){
document.getElementsByName("apid")[0].style.display="";
document.getElementsByName("apid")[1].style.display="none";
document.getElementsByName("apid")[2].style.display="none";
}
if(document.getElementById("sel").value=="2"){
document.getElementsByName("apid")[0].style.display="";
document.getElementsByName("apid")[1].style.display="";
document.getElementsByName("apid")[2].style.display="none";
}
if(document.getElementById("sel").value=="3"){
document.getElementsByName("apid")[0].style.display="";
document.getElementsByName("apid")[1].style.display="";
document.getElementsByName("apid")[2].style.display="";
}
  }
  </script>
</html>
--------------------编程问答-------------------- --------------------编程问答--------------------



<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>

<%

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

%>



<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

  <head>

  <base href="<%=basePath%>">

    

  <title>My JSP 'index.jsp' starting page</title>

<meta http-equiv="pragma" content="no-cache">

<meta http-equiv="cache-control" content="no-cache">

<meta http-equiv="expires" content="0">   

<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">

<meta http-equiv="description" content="This is my page">

<!--

<link rel="stylesheet" type="text/css" href="styles.css">

-->

  </head>

   

  <body>

  <form action="form" method="post">

 	 <table>

  <tr>

<td>  

<select id="sel" onChange="chg()" >

<option value="1" >1</option>

<option value="2">2</option>

<option value="3">3</option>

</select>

</td>

  </tr>

  <tr>

  <td><input type="text" id ="apid" name="apid" value="1"/></td><td><input type="text" id ="apid" name="apid" value="2"/></td><td><input type="text" id ="apid" name="apid" value="3"/></td>

  </tr>

 	 </table>

  </form>

  </body>

  <script type="text/javascript">

var mycars = new Array()

alert (mycars.length);

mycars[0] = "Saab"

mycars[1] = "Volvo"

mycars[2] = "BMW"

if(mycars.length == 3) {

alert (mycars.length);

var sel=document.getElementById('sel');

var option=sel.options[sel.selectedIndex = 0];

document.getElementsByName("apid")[0].value="46";

}

  

 	 if(document.getElementById("sel").value=="1"){

document.getElementsByName("apid")[1].style.display="none";

document.getElementsByName("apid")[2].style.display="none";

} else if (document.getElementById("sel").value=="2") {

document.getElementsByName("apid")[2].style.display="none";

}





  function chg(){

if(document.getElementById("sel").value=="1"){

document.getElementsByName("apid")[0].style.display="";

document.getElementsByName("apid")[1].style.display="none";

document.getElementsByName("apid")[2].style.display="none";

}

if(document.getElementById("sel").value=="2"){

document.getElementsByName("apid")[0].style.display="";

document.getElementsByName("apid")[1].style.display="";

document.getElementsByName("apid")[2].style.display="none";

}

if(document.getElementById("sel").value=="3"){

document.getElementsByName("apid")[0].style.display="";

document.getElementsByName("apid")[1].style.display="";

document.getElementsByName("apid")[2].style.display="";

}

  }

  </script>

</html>

补充：Java ,  J2ME