php如何实现无限极分类?无限极分类的三种实现方法（代码详解）

public function judeg($id)
{
   $rs = Db::name('finance_class') -> field('parent_code') -> where('id',$id) -> select();
   $i = 1;
   foreach($rs as $k => $v){
   　　if($v['parent_code'] <> 0){
   　　　　$i += $this -> judeg($v['parent_code']);
      }
   }
   return $i;
}

 public function cid($id,$pid)
 {
    $w['parent_code'] = $id;
    $rs = Db::name('finance_class')
       -> field('id,code,name,parent_code')
       -> where($w)
       -> order('code asc')
       -> select();
    $str = '';
    foreach ($rs as $k => $v) {
        $name = $v['name'];
        $_id = $v['id'];
        $cutOff = '';
        for($i = 0; $i < $this -> judeg($_id); $i++){
        　　$cutOff.='-';
        }
        if($_id == $pid){
        　　$str.='<p>他的id='.$_id.'====他的级别'.$cutOff.$name.'</p>';
        }else{
        　　$str.='<p>他的id='.$_id.'====他的级别'.$cutOff.$name.'</p>';
        }
        $str.=$this->cid($_id,$pid);
    }
    return $str;
37}
public function finance_c()
{
   $w['type'] = '资产类';
   $w['parent_code'] = 0;
   $rs = Db::name('finance_class')
     　　-> field('id,code,name,parent_code')
     　　-> where($w)
        -> select();
   $str = '';
   foreach ($rs as $k => $v){
   　　$str.= '<p>一级name:'.$v['name'].'</p><p><span>立即学习</span>“<a href="https://pan.quark.cn/s/7fc7563c4182" style="text-decoration: underline !important; color: blue; font-weight: bolder;" rel="nofollow" target="_blank">PHP免费学习笔记（深入）</a>”；</p>';
   　　$str.=    $this -> cid($v['id'],0);
   }
   echo $str;
}

public function getVoucherClass()
{
    $lists = Db::name('finance_class')->select();

    $lists = $this->getTree($lists);

    foreach($lists as $value){
    　　echo str_repeat('--', $value['level']), $value['name'].'<br />';
    }
10}

/**
* 递归实现无限极分类
* @param $array 分类数据
* @param $pid 父ID
* @param $level
* @return $list 
*/
function getTree($array, $pid =0, $level = 0){
   static $list = [];
   foreach ($array as $key => $value){
   　　if ($value['parent_code'] == $pid){
      　 $value['level'] = $level;
         $list[] = $value;
         unset($array[$key]);
         $this->getTree($array, $value['id'],$level+1);
      }
   }
   return $list;
30}

 public function index()
    {
       $lists = \think\Db::table('ozyx_finance_class')->select();
       $lists = $this->getTree($lists,0);

       foreach ($lists as $k => $v) {
               $lists_one[$v['type']][]=$v;
       }

       // halt($lists_one);
       $this->assign('lists', $lists_one);

       return view();
    }

    /**
    * 无限极分类
    */
    function getTree($data, $pid)
    {
        $tree = '';
        foreach($data as $k => $v)
        {
          if($v['parent_code'] == $pid)
          {        
               $v['parent_code'] = $this->getTree($data, $v['id']);
               $tree[] = $v;
                  unset($data[$k]);
          }
        }
        return $tree;
    }