$name = substr($name, 0, 2) . DS . substr($name, 2);
        }
        if ($this->options['prefix']) {
            $name = $this->options['prefix'] . DS . $name;
        }
        $filename = $this->options['path'] . $name . '.php';
        $dir      = dirname($filename);

        if ($auto && !is_dir($dir)) {
            mkdir($dir, 0777, true);
        }
        return $filename;
    }

    /**
     * 判断缓存是否存在
     * @access public
     * @param string $name 缓存变量名
     * @return bool