PHP无限分类代码，支持数组格式化、直接输出菜单两种方式

代码如下：

<?php 
/** 
+------------------------------------------------ 
* 通用的树型类 
+------------------------------------------------ 
* @author [email protected] 
+------------------------------------------------ 
* @date 2010年11月23日10:09:31 
+------------------------------------------------ 
*/ 
class Tree 
{ 

/** 
+------------------------------------------------ 
* 生成树型结构所需要的2维数组 
+------------------------------------------------ 
* @author [email protected] 
+------------------------------------------------ 
* @var Array 
*/ 
var $arr = array(); 

/** 
+------------------------------------------------ 
* 生成树型结构所需修饰符号，可以换成图片 
+------------------------------------------------ 
* @author [email protected] 
+------------------------------------------------ 
* @var Array 
*/ 
var $icon = array('│','├',' └'); 

/** 
* @access private 
*/ 
var $ret = ''; 

/** 
* 构造函数，初始化类 
* @param array 2维数组，例如： 
* array( 
* 1 => array('id'=>'1','parentid'=>0,'name'=>'一级栏目一'), 
* 2 => array('id'=>'2','parentid'=>0,'name'=>'一级栏目二'), 
* 3 => array('id'=>'3','parentid'=>1,'name'=>'二级栏目一'), 
* 4 => array('id'=>'4','parentid'=>1,'name'=>'二级栏目二'), 
* 5 => array('id'=>'5','parentid'=>2,'name'=>'二级栏目三'), 
* 6 => array('id'=>'6','parentid'=>3,'name'=>'三级栏目一'), 
* 7 => array('id'=>'7','parentid'=>3,'name'=>'三级栏目二') 
* ) 
*/ 
function tree($arr=array()) 
{ 
$this->arr = $arr; 
$this->ret = ''; 
return is_array($arr); 
} 

/** 
* 得到父级数组 
* @param int 
* @return array 
*/ 
function get_parent($myid) 
{ 
$newarr = array(); 
if(!isset($this->arr[$myid])) return false; 
$pid = $this->arr[$myid]['pid']; 
$pid = $this->arr[$pid]['pid']; 
if(is_array($this->arr)) 
{ 
foreach($this->arr as $id => $a) 
{ 
if($a['pid'] == $pid) $newarr[$id] = $a; 
} 
} 
return $newarr; 
} 

/** 
* 得到子级数组 
* @param int 
* @return array 
*/ 
function get_child($myid) 
{ 
$a = $newarr = array(); 
if(is_array($this->arr)) 
{ 
foreach($this->arr as $id => $a) 
{ 
if($a['pid'] == $myid) $newarr[$id] = $a; 
} 
} 
return $newarr ? $newarr : false; 
} 

/** 
* 得到当前位置数组 
* @param int 
* @return array 
*/ 
function get_pos($myid,&$newarr) 
{ 
$a = array(); 
if(!isset($this->arr[$myid])) return false; 
$newarr[] = $this->arr[$myid]; 
$pid = $this->arr[$myid]['pid']; 
if(isset($this->arr[$pid])) 
{ 
$this->get_pos($pid,$newarr); 
} 
if(is_array($newarr)) 
{ 
krsort($newarr); 
foreach($newarr as $v) 
{ 
$a[$v['id']] = $v; 
} 
} 
return $a; 
} 

/** 
* ------------------------------------- 
* 得到树型结构 
* ------------------------------------- 
* @author [email protected] 
* @param $myid 表示获得这个ID下的所有子级 
* @param $str 生成树形结构基本代码, 例如: "<option value=\$id \$select>\$spacer\$name</option>" 
* @param $sid 被选中的ID, 比如在做树形下拉框的时候需要用到 
* @param $adds 
* @param $str_group 
*/ 
function get_tree($myid, $str, $sid = 0, $adds = '', $str_group = '') 
{ 
$number=1; 
$child = $this->get_child($myid); 
if(is_array($child)) { 
$total = count($child); 
foreach($child as $id=>$a) { 
$j=$k=''; 
if($number==$total) { 
$j .= $this->icon[2]; 
} else { 
$j .= $this->icon[1]; 
$k = $adds ? $this->icon[0] : ''; 
} 
$spacer = $adds ? $adds.$j : ''; 
$selected = $id==$sid ? 'selected' : ''; 
@extract($a); 
$parentid == 0 && $str_group ? eval("\$nstr = \"$str_group\";") : eval("\$nstr = \"$str\";"); 
$this->ret .= $nstr; 
$this->get_tree($id, $str, $sid, $adds.$k.' ',$str_group); 
$number++; 
} 
} 
return $this->ret; 
} 

/** 
* 同上一方法类似,但允许多选 
*/ 
function get_tree_multi($myid, $str, $sid = 0, $adds = '') 
{ 
$number=1; 
$child = $this->get_child($myid); 
if(is_array($child)) 
{ 
$total = count($child); 
foreach($child as $id=>$a) 
{ 
$j=$k=''; 
if($number==$total) 
{ 
$j .= $this->icon[2]; 
} 
else 
{ 
$j .= $this->icon[1]; 
$k = $adds ? $this->icon[0] : ''; 
} 
$spacer = $adds ? $adds.$j : ''; 

$selected = $this->have($sid,$id) ? 'selected' : ''; 
@extract($a); 
eval("\$nstr = \"$str\";"); 
$this->ret .= $nstr; 
$this->get_tree_multi($id, $str, $sid, $adds.$k.' '); 
$number++; 
} 
} 
return $this->ret; 
} 

function have($list,$item){ 
return(strpos(',,'.$list.',',','.$item.',')); 
} 

/** 
+------------------------------------------------ 
* 格式化数组 
+------------------------------------------------ 
* @author [email protected] 
+------------------------------------------------ 
*/ 
function getArray($myid=0, $sid=0, $adds='') 
{ 
$number=1; 
$child = $this->get_child($myid); 
if(is_array($child)) { 
$total = count($child); 
foreach($child as $id=>$a) { 
$j=$k=''; 
if($number==$total) { 
$j .= $this->icon[2]; 
} else { 
$j .= $this->icon[1]; 
$k = $adds ? $this->icon[0] : ''; 
} 
$spacer = $adds ? $adds.$j : ''; 
@extract($a); 
$a['title'] = $spacer.' '.$a['title']; 
$this->ret[$a['id']] = $a; 
$fd = $adds.$k.' '; 
$this->getArray($id, $sid, $fd); 
$number++; 
} 
} 

return $this->ret; 
} 
} 
?>