PHP文件缓存实现方法与技巧

class FileCache {
    private $cacheDir;

    public function __construct($dir = 'cache/') {
        $this->cacheDir = rtrim($dir, '/') . '/';
        if (!is_dir($this->cacheDir)) {
            mkdir($this->cacheDir, 0755, true);
        }
    }

    // 获取缓存
    public function get($key) {
        $file = $this->cacheDir . $key . '.cache';
        if (!file_exists($file)) return false;

        $data = unserialize(file_get_contents($file));
        if ($data['expire'] < time()) {
            unlink($file);
            return false;
        }
        return $data['content'];
    }

    // 设置缓存，$ttl 单位秒
    public function set($key, $value, $ttl = 3600) {
        $data = [
            'content' => $value,
            'expire'  => time() + $ttl
        ];
        $tmpFile = $this->cacheDir . uniqid('tmp_', true);
        $finalFile = $this->cacheDir . $key . '.cache';

        if (file_put_contents($tmpFile, serialize($data))) {
            return rename($tmpFile, $finalFile);
        }
        return false;
    }

    // 删除缓存
    public function delete($key) {
        $file = $this->cacheDir . $key . '.cache';
        return file_exists($file) ? unlink($file) : true;
    }

    // 清除所有过期缓存
    public function gc() {
        foreach (glob($this->cacheDir . '*.cache') as $file) {
            $data = @unserialize(file_get_contents($file));
            if (!$data || $data['expire'] < time()) {
                unlink($file);
            }
        }
    }
}