@Override
  public UniformRuleConfigMapping load() {
    for (String extension : SUPPORT_EXTENSIONS) {
      InputStream in = null;
      try {
        in = this.getClass().getResourceAsStream("/" + getFileNameByExt(extension));
        if (in != null) {
          RuleConfigParser parser = PARSER_MAP.get(extension);
          return parser.parse(in);
        }
      } finally {
        if (in != null) {
          try {
            in.close();
          } catch (IOException e) {
            log.error("close file error:{}", e);
          }
        }
      }
    }
    return null;
  }
TODO(zheng): handle the case: multiply rule files.
src/main/java/com/eudemon/ratelimiter/rule/source/FileRuleConfigSource.java