php iframe实现无刷新文件上传（无需ajax)

class upload
{
   public $_file;

   public function __construct( $name =null)
   {
       if(is_null($name) || !isset($_FILES[$name]))
            $name = key($_FILES);
           
       if(!isset($_FILES[$name]))
           throw new Exception("并没有文件上传");
          
       $this->_file  = $_FILES[$name];
      
       if(!is_uploaded_file($this->_file['tmp_name']))
            throw new Exception("异常情况");
       if($this->_file['error'] !== 0)
            throw new Exception("错误代码:".$this->_file['error']);    
   }
   public function moveTo( $new_dir)
   {
       $real_dir = $this->checkDir($new_dir);
       return move_uploaded_file($this->_file['tmp_name'], $real_dir.'/'.$this->_file['name']);
   }
   private function checkDir($dir)
   {
       $real_dir = realpath($dir);
       if($real_dir === false)
           throw new Exception("给定目录{$dir}不存在");
       if(!is_writable($real_dir))
           throw new Exception("给定目录{$dir}不可写");
       return $real_dir;
   }

}

$inputName =  'uploadfile';
 // 即 中的name值，不填也行
$upload = new upload($inputName);
$new_dir = "/www";  // 将文件移动到的路径
$upload->moveTo($new_dir);