Example analysis of how to use static variables in PHP

public static $endpoint,$accessKeyId,$accessKeySecret,$bucket;

protected function _initialize() {
  self::$endpoint = C('OSS_ENDPOINT');
  self::$accessKeyId = C('OSS_ACCESS_ID');
  self::$accessKeySecret = C('OSS_ACCESS_KEY');
  self::$bucket = C('OSS_TEST_BUCKET');
}

public static function getOssClient()
{
  try {
   $ossClient = new OssClient(self::$accessKeyId, self::$accessKeySecret, self::$endpoint, false);
  } catch (OssException $e) {
   printf(__FUNCTION__ . "creating OssClient instance: FAILED\n");
   printf($e->getMessage() . "\n");
   return null;
  }
  return $ossClient;
}