{$this->readTimes++;$filename = $this->getCacheKey($name);if (!is_file($filename)) {return $default;}$content = file_get_contents($filename);$this->expire = null;if (false !== $content) {$expire = (int) substr($content, 8, 12);if (0 != $expire && time() > filemtime($filename) + $expire) {//缓存过期删除缓存文件$this->unlink($filename);return $default;}