public function has($key)
    {
        $file = $this->getFileName($key);

        if ( !file_exists($file) )
        {
            return false;
        }

        // if cache file expire
        if ( filemtime($file) >= time() )
        {
            static::$keys[$key] = true;

            return true;
        }
        else
        {
            unset(static::$keys[$key]);
            unlink($file);

            return false;
        }
    }
public function has($key)
    {
        $file = $this->getFileName($key);

        if ( !file_exists($file) )
        {
            return false;
        }

        // if cache file expire
        if ( filemtime($file) >= time() )
        {
            static::$keys[$key] = true;

            return true;
        }
        else
        {
            unset(static::$keys[$key]);
            unlink($file);

            return false;
        }
    }
public function has ( $ key ) { $ file = $ this -> getFileName ( $ key ) ; if ( ! file_exists ( $ file ) ) { return false ; } // if cache file expire
 if ( filemtime ( $ file ) >= time ( ) ) { static :: $ keys [ $ key ] = true ; return true ; } else { unset ( static :: $ keys [ $ key ] ) ; unlink ( $ file ) ; return false ; } }
Check has cache key

@param string $key
@return bool
Check has cache key