php缓存数组到文件

php缓存数组到文件

static function getIDs($kemuid)
 {
  $cachefile="cache/" . $kemuid . ".cache";
  $datas=array();
  if (!file_exists($cachefile)||time() > (filemtime($cachefile) + 14400))
  //缓存不存在或超过4小时
  {
   global $data;
   //读取 id 集
   $query="SELECT sid FROM shiti WHERE skemu = " . intval($kemuid);
   $res = $data->query($query);
   while($r = $data->fetchArray($res))
   {
    $datas[]=$r['sid'];
   }
   //写入缓存
   file_put_contents($cachefile,serialize($datas));
   /*
      $fp= fopen($cachefile, "w");
      fwrite($fp, serialize($datas));
      fclose($fp);

   */
  }
  else
  {
   //读出缓存
   $fp = fopen($cachefile,'r');//读
   $datas = unserialize(fread($fp,filesize($cachefile)));//反序列化，并赋值
  }
  return $datas;
 }