如何使用php创建无限级树型菜单 【通用的树型类】

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')
          )

var $icon = array('│','├','└');
var $ret = '';
var $html='';

function tree($arr=array())
    {
       $this->arr = $arr;
       $this->ret = '';
       return is_array($arr);
    }

function get_parent($myid)
    {
        $newarr = array();
        if(!isset($this->arr[$myid])) return false;
        $pid = $this->arr[$myid]['parentID'];
        $pid = $this->arr[$pid]['parentID'];
        if(is_array($this->arr))
        {
            foreach($this->arr as $id => $a)
            {
                if($a['parentID'] == $pid) $newarr[$id] = $a;
            }
        }
        return $newarr;
    }

function get_child($myid)
    {
        $a = $newarr = array();
        if(is_array($this->arr))
        {
            foreach($this->arr as $id => $a)
            {
                if(@$a['parentID'] == $myid) {
                    $newarr[$id] = $a;
                }
            }
        }
        return $newarr ? $newarr : false;
    }

function get_pos($myid,&$newarr)
    {
        $a = array();
        if(!isset($this->arr[$myid])) return false;
        $newarr[] = $this->arr[$myid];
        $pid = $this->arr[$myid]['parentID'];
        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;
    }

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 = $a["id"]==$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;
    }

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.','));
    }

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['name'] = $spacer.' '.$a['name'];
                $this->ret[$a['id']] = $a;
                $fd = $adds.$k.' ';
                $this->getArray($id, $sid, $fd);
                $number++;
            }
        }
 
        return $this->ret;
    }

public function arrToTree($data,$pid){
        $tree = array();
        foreach($data as $k => $v){
            if($v['parentID'] == $pid){
                $v['parentID'] = $this->arrToTree($data,$v['id']);
                $tree[] = $v;
            }
        }   
        return $tree;
    }

public function outToHtml($tree){
        $html = '';
        foreach($tree as $t){
            if(empty($t['parentID'])){
                $html .= "<li><a href=\"javascript:\" onclick=\"$.bringBack({id:'$t[id]',name:'$t[name]'})\">$t[name]</a></li>";
            }else{
                $html .='<li><a href="javascript:">'.$t['name'].'</a><ul>';
                $html .= $this->outToHtml($t['parentID']);
                $html  = $html.'</ul></li>';
            }
        } 
        return $html;
    }

$tree = new tree;
 $tree->tree($categorys);
 echo "<select name=\"f_id\" >";
 echo "<option value='0' >添加一级分类</option>";
 //get_tree(父ID,格式化字符窜,默认选中哪个分类,修饰前缀,父级分类样式) 前面两个必填，后面三个可选
 $data .= $tree->get_tree(0, "<option value='\$id' \$selected>\$spacer\$name</option>\n", 0, '' , "<optgroup label='\$name'></optgroup>");
 echo $data;
 echo "</select>";