code: public static String imgToBase64StrWithPrefix(byte[] imageBytes, String formatName) {
          formatName = formatName != null ? formatName : "jpeg";
          return String.format("data:image/%s;base64,%s", formatName, CommonUtils.bytesToBase64Str(imageBytes));
      }
docs: 将指定的图片字节数组进行Base64编码并返回
  
  @param imageBytes 指定的图片字节数组
  @param formatName 图片格式名,如gif,png,jpg,jpeg等,默认为jpeg
  @return 编码后的Base64字符串