没有人规定一定要使用类，你写成一个函数也可以，每个人的编程习惯、风格、喜好都不一样，关于封装成类是为了使这段程序具有结构条理性，而不是随意放置，关于类中包含的多个方法（vtree、htree）主要应对不同业务场景，vtree为单线纵向结构，而htree为树形结构。
ClassTree.class.php
&$v) {
if(!empty($v['sub'])){
$v['sub']=self::sort($v['sub'],$cols);
}
$sort[$k]=$v[$cols];
}
if(isset($sort))
array_multisort($sort,SORT_DESC,$arr);
return $arr;
}
/**
* 横向分类树
*/
static public function hTree($arr,$pid=0){
foreach($arr as $k => $v){
if($v['pid']==$pid){
$data[$v['id']]=$v;
$data[$v['id']]['sub']=self::hTree($arr,$v['id']);
}
}
return isset($data)?$data:array();
}
/**
* 纵向分类树
*/
static public function vTree($arr,$pid=0){
foreach($arr as $k => $v){
if($v['pid']==$pid){
$data[$v['id']]=$v;
$data+=self::vTree($arr,$v['id']);
}
}
return isset($data)?$data:array();
}
}返回例子：
magento(麦进斗)
下载
Magento是一套专业开源的PHP电子商务系统。Magento设计得非常灵活，具有模块化架构体系和丰富的功能。易于与第三方应用系统无缝集成。Magento开源网店系统的特点主要分以下几大类，网站管理促销和工具国际化支持SEO搜索引擎优化结账方式运输快递支付方式客户服务用户帐户目录管理目录浏览产品展示分析和报表Magento 1.6 主要包含以下新特性：•持久性购物 - 为不同的
Array
(
[4] => Array
(
[id] => 4
[pid] => 0
[name] => 上海
[sort] => 2
)
[5] => Array
(
[id] => 5
[pid] => 4
[name] => 闵行
[sort] => 0
)
[1] => Array
(
[id] => 1
[pid] => 0
[name] => 浙江
[sort] => 0
)
[13] => Array
(
[id] => 13
[pid] => 1
[name] => 金华
[sort] => 1
)
[10] => Array
(
[id] => 10
[pid] => 1
[name] => 宁波
[sort] => 0
)
[6] => Array
(
[id] => 6
[pid] => 10
[name] => 宁海
[sort] => 0
)
)
Array
(
[4] => Array
(
[id] => 4
[pid] => 0
[name] => 上海
[sort] => 2
[sub] => Array
(
[5] => Array
(
[id] => 5
[pid] => 4
[name] => 闵行
[sort] => 0
[sub] => Array
(
)
)
)
)
[1] => Array
(
[id] => 1
[pid] => 0
[name] => 浙江
[sort] => 0
[sub] => Array
(
[13] => Array
(
[id] => 13
[pid] => 1
[name] => 金华
[sort] => 1
[sub] => Array
(
)
)
[10] => Array
(
[id] => 10
[pid] => 1
[name] => 宁波
[sort] => 0
[sub] => Array
(
[6] => Array
(
[id] => 6
[pid] => 10
[name] => 宁海
[sort] => 0
[sub] => Array
(
)
)
)
)
)
)
)public function vTree($arr,$pid=0){
foreach($arr as $k => $v){
if($v['pid']==$pid){
$data[$v['id']]=$v;
$data+=vTree($arr,$v['id']);
}
}
return isset($data)?$data:array();
} 
