麻烦给个树形结构最简单的例子


<html>
<head>
<style type="text/css">
<!--
.style2 {
color: #C2C6D5
}

a,A:link,a:visited,a:active {
color: #C2C6D5;
text-decoration: none;
font-family: Verdana, Tahoma;
font-size: 12px
}

A:hover {
color: #ff0000;
text-decoration: none;
font-family: Verdana, Tahoma;
font-size: 12px
}

p,tr,td,ul,li {
color: #000000;
font-family: Verdana, Tahoma;
font-size: 12px
}

.header1,h1 {
color: #ffffff;
background: #4682B4;
font-weight: bold;
font-family: Verdana, Tahoma;
font-size: 13px;
margin: 0px;
padding: 2px;
}

.header2,h2 {
color: #000000;
background: #DBEAF5;
font-weight: bold;
font-family: Verdana, Tahoma;
font-size: 12px;
}

.intd {
color: #000000;
font-family: Verdana, Tahoma;
font-size: 12px;
padding-left: 15px;
padding-right: 15px;
}

.ctrl {
font-family: Verdana, Tahoma, sans-serif;
font-size: 12px;
width: 100%;
}

form {
margin: 2px;
}

.menuP {
color: #C2C6D5;
font-family: Verdana, Tahoma;
font-size: 12px;
}

.menuP a {
text-decoration: underline;
}
-->
</style>
</head>
<body>

<table cellspacing="0" cellpadding="0" border="0">
<tbody>
<tr>
<td nowrap="">
<a onmouseout="trees[0].tmH(3)" onmouseover="trees[0].tmJ(3)"
href="javascript: trees[0].tmB(3)"> <img border="0"
align="absbottom" name="j_img0_3" src="images/minusbottom.gif" />
</a>
<a id="i_txt0_3" class="t0i" onmouseout="trees[0].tmH(3)"
onmouseover="trees[0].tmJ(3)" ondblclick="trees[0].tmB(3)"
onclick="return trees[0].tmG(3)" target="mainFrame"
href="SearchStudent.php?menu_id=44"> <img class="t0im"
border="0" align="absbottom" name="i_img0_3"
src="images/folderopen.gif" /> Student </a>
</td>
</tr>
</tbody>
</table>
<div id="i_div0_3" style="display: block;">
<table cellspacing="0" cellpadding="0" border="0">
<tbody>
<tr>
<td nowrap="">
<img border="0" align="absbottom" src="images/line.gif" />
<img border="0" align="absbottom" src="images/joinbottom.gif" />
<a id="i_txt0_4" class="t0i" onmouseout="trees[0].tmH(4)"
onmouseover="trees[0].tmJ(4)" ondblclick="trees[0].tmB(4)"
onclick="return trees[0].tmG(4)" target="mainFrame"
href="SearchStudent.php?menu_id=3"> <img class="t0im"
border="0" align="absbottom" name="i_img0_4"
src="images/page.gif" /> Search verified </a>
</td>
</tr>
</tbody>
</table>
<table cellspacing="0" cellpadding="0" border="0">
<tbody>
<tr>
<td nowrap="">
<img border="0" align="absbottom" src="images/line.gif" />
<img border="0" align="absbottom" src="images/join.gif" />
<a id="i_txt0_5" class="t0i" onmouseout="trees[0].tmH(5)"
onmouseover="trees[0].tmJ(5)" ondblclick="trees[0].tmB(5)"
onclick="return trees[0].tmG(5)" target="mainFrame"
href="student_new.php?menu_id=4"> <img class="t0im"
border="0" align="absbottom" name="i_img0_5"
src="images/page.gif" /> New student </a>
</td>
</tr>
</tbody>
</table>
</div> </body>
我是从我做的一个网站中截取下来的。里面的图片可能无法正常显示，但是原理你看就应该明白了。^_^