php 无限级分类，超级简单的无限级分类，支持输

<?php
error_reporting(E_ALL ^ E_NOTICE);

class Tree
{
 
  /
   +------------------------------------------------
    生成树型结构所需要的2维数组
   +------------------------------------------------
    @author abc
   +------------------------------------------------
    @var Array
   /
  var $arr = array();
 
  /
   +------------------------------------------------
    生成树型结构所需修饰符号，可以换成图片
   +------------------------------------------------
    @author abc
   +------------------------------------------------
    @var Array
   /
  var $icon = array(' │',' ├',' └');
 
  /
   @aess 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]['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;
  }
 
  /
   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['parentid'] == $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]['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;
  }
 
  /
    -------------------------------------
    得到树型结构
    -------------------------------------
    @author abc
    @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.'&nbsp;',$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.'&nbsp;');
        $number++;
      }
    }
    return $this->ret;
  }
 
  function have($list,$item){
    return(strpos(',,'.$list.',',','.$item.','));
  }
 
  /
   +------------------------------------------------
    格式化数组
   +------------------------------------------------
    @author abc
   +------------------------------------------------
   /
  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.'&nbsp;';
        $this->getArray($id, $sid, $fd);
        $number++;
      }
    }
 
    return $this->ret;
  }
}



$data=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'=>''), 
		 8 => array('id'=>'8','parentid'=>3,'name'=>'三级栏目三'),
		 9 => array('id'=>'9','parentid'=>7,'name'=>'四级分类三'),
     ); 
$tree = new Tree;      
$tree->tree($data);    
 
// 如果使用数组, 请使用 getArray方法 
//$tree->getArray(); 
// 下拉菜单选项使用 get_tree方法 
$html='<select name="tree">'; 
$str = "<option value=\$id \$select>\$spacer\$name</option>"; 
$html .= $tree->get_tree(0,$str,-1).'</select>'; 
echo $html; 
?>