session_start(): Cannot start session when headers already sent

            // 读取session驱动
            $class = false !== strpos($config['type'], '\\') ? $config['type'] : '\\think\\session\\driver\\' . ucwords($config['type']);

            // 检查驱动类
            if (!class_exists($class) || !session_set_save_handler(new $class($config))) {
                throw new ClassNotFoundException('error session handler:' . $class, $class);
            }
        }
        if ($isDoStart) {
            session_start();
            self::$init = true;
        } else {
            self::$init = false;
        }
    }

    /**
     * session自动启动或者初始化
     * @return void