AES/ECB/PKCS5Padding

String aesEncode(String content, String aesKey) {
    //加密key
    final key = encrypt.Key.fromUtf8(aesKey);
    //偏移量 - 注意这里
    final iv = encrypt.IV.fromSecureRandom(0);

    //设置cbc模式
    final encrypter = encrypt.Encrypter(
        encrypt.AES(key, mode: encrypt.AESMode.ecb, padding: 'PKCS7'));
    //加密
    final encrypted = encrypter.encrypt(content, iv: iv);
    return encrypted.base64;
  }