HarmonyOS base64编解码错误，出现异常数据

编写base64工具类，测试后结果有问题，base64编码结果中出现 【%{public}s】，解码也不对

/**
 * base64编码
 */
public static base64Encode(value: string): string {
  let base64Helper = new util.Base64Helper();
  let textEncoder = util.TextEncoder.create("utf-8");
  return base64Helper.encodeToStringSync(textEncoder.encodeInto(value));
}

/**
 * base64解码
 */
public static base64Decode(value: string): string {
  let base64Helper = new util.Base64Helper();
  let textDecoder = util.TextDecoder.create("utf-8");
  return textDecoder.decodeWithStream(base64Helper.decodeSync(value));
  // return Unit8ArrayUtil.uint8ArrayToString(base64Helper.decodeSync(value));
}
==============
let result = EncryptUtil.base64Encode('{"pageCode":"page_birds_balance_connect"}');
Logger.info("base64Encode--result:" + result);

日志： base64Encode--result:cGFnZV9iaXJkc19iYWxhbmNlX2Nvbm5lY3Q=, %{public}s
  ================
  let result2 = EncryptUtil.base64Decode("eyJwYWdlQ29kZSI6InBhZ2VfYmlyZHNfYmFsYW5jZV9jb25uZWN0In0");
Logger.info("base64Encode--result2:" + result2);

日志：base64Encode--result2:{"pageCode":"page_birds_balance_connect, %{public}s