jquery实现树形二级菜单

直接上代码：

[html]
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>jQuery实现的树形列表菜单(Menu Tree) - 分享JavaScript-sharejs.com</title>
<meta name="Copyright" content="JavaScript分享网 http://www.sharejs.com/" />
<meta name="description" content="jQuery实现的树形列表菜单(Menu Tree),JavaScript分享网" />
<meta content="JavaScript,分享,JavaScript代码,Ajax" name="keywords" />

<style type="text/css">
.padding {height:300px;}
This copyright notice must be kept untouched in the stylesheet at
all times.

The original version of this stylesheet and the associated (x)html
is available at http://www.stunicholls.com/menu/jquery-menutree.html
Copyright (c) 2005-2008 Stu Nicholls. All rights reserved.
This stylesheet and the associated (x)html may be modified in any
way to fit your requirements.


#wrap {position:relative; height:200px; width:130px; z-index:100;}
#nav {position:absolute; left:0; top:0;}
#nav,
#nav ul {padding:0; margin:0; list-style:none; font-family:arial, sans-serif; background:#fff; font-weight:bold;}
#nav li a {padding-left:20px; white-space:nowrap;}
#nav li ul li a {padding-left:0;}

#nav ul {padding-left:20px;}
#nav li a {color:#66b; text-decoration:none; font-size:11px;}
#nav li {font-size:13px; line-height:25px; color:#d80; cursor:pointer; width:100%;}
#nav li.down {text-indent:20px;}

#nav li a:hover {text-decoration:underline;}

</style>

<script type="text/javascript" src="http://www.sharejs.com/software/jquery/jquery-1.3.2.min.js"></script>

<script type="text/javascript">
This copyright notice must be untouched at all times.
Copyright (c) 2008 Stu Nicholls - stunicholls.com - all rights reserved.

$(document).ready(function() {

$("ul#nav ul").hide();
$('ul#nav li:has(ul)').each(function(i) {
$(this).children().slideUp(400);
}); www.zzzyk.com

$('li.p1:has(ul)').click(function(event){
        if (this == event.target) {
        current = this;
        $('ul#nav li:has(ul)').each(function(i) {
        if (this != current) {$(this).children().slideUp(400);}
        });
        $(this).children("ul:eq(0)").slideToggle(400);
        }
    });

});

</script>

</head>
<body>

<div id="wrap">
<ul id="nav">
<li><a href="#url">Home</a></li>
<li class="p1 down">Products
    <ul>
        <li><a href="#url">Flashguns</a></li>
        <li><a href="#url">Tripods</a></li>
        <li><a href="#url">Filters</a></li>
    </ul>
</li>
<li class="p1 down">Services
    <ul>
        <li><a href="#url">Printing</a></li>
        <li><a href="#url">Photo Framing</a></li>
        <li><a href="#url">Retouching</a></li>
        <li><a href="#url">Archiving</a></li>
    </ul>
</li>
</ul>
</div>
</body>
</html>
其中的jquery的地址自己得换一个能够找到的，要不没有效果

补充：web前端 , JavaScript ,