用户类

class User{
    public  $uid;
    public  $userName;
    public  $groupId;
    public  static $Uid;
    public  static $Uname;
    public  static $group_Id;
    private static $_instance;
    private function __construct() {
        if(!isset($_SESSION)){
            session_start();
        }
        if(!empty($_SESSION)){
            $this->uid      =   $_SESSION['userinfo']['id'];
            $this->userName =   $_SESSION['userinfo']['username'];
            $this->groupId  =   $_SESSION['userinfo']['group_id'];
        }
    }
    public static function getInstance(){
        if(!(self::$_instance instanceof self)){
            self::$_instance    =   new self;
            self::$Uid          =   self::$_instance->uid;
            self::$Uname        =   self::$_instance->userName;
            self::$group_Id     =   self::$_instance->groupId;
        }
        return self::$_instance;
    }
    public function __clone() {
        trigger_error('Clone is not allow!',E_USER_ERROR);
    }
}