HarmonyOS 鸿蒙Next如何处理base64解码含不支持字符The input string contains unsupported characters

根据报错信息提示：输入字符串包含不支持的字符，可以先把字符串处理一下，参考以下demo

// 字符串转成字节流
function stringToUint8Array(str: string) {
  return new Uint8Array(buffer.from(str, 'utf-8').buffer);
}

// 字节流转成可理解的字符串
function uint8ArrayToString(array: Uint8Array): string {
  // 将UTF-8编码转换成Unicode编码
  let out: string = "";
  let index: number = 0;
  let len: number = array.length;
  while (index < len) {
    let character = array[index++];
    switch (character >> 4) {
      case 0:
      case 1:
      case 2:
      case 3:
      case 4:
      case 5:
      case 6:
      case 7:
        out += String.fromCharCode(character); 
        break;
      case 12:
      case 13:
        out += String.fromCharCode(((character & 0x1F) << 6) | (array[index++] & 0x3F));
        break;
      case 14:
        out += String.fromCharCode(((character & 0x0F) << 12) | ((array[index++] & 0x3F) << 6) | ((array[index++] & 0x3F) << 0));
        break;
      default:
        break;
    }
  }
  return out;
}

function doDecryption(encodeString: string) {
  let base64_ = new util.Base64Helper();
  let decodeArr: Uint8Array = base64_.decodeSync(encodeString);
  let decodeStr = uint8ArrayToString(decodeArr);

  log.info('doEncrypted, decodeArr: ' + decodeArr);
  log.info('doEncrypted, decodeStr: ' + decodeStr);
}