code: public static String createUniqueFileName(String fileName) {
  
          int    index  = fileName.lastIndexOf(".");
          String suffix = fileName.substring(index);
          String uqName = UUIDUtils.getUUID16() + suffix;
          return uqName;
      }
docs: 保留原文件后缀生成唯一文件名
  
  @param fileName
  @return