在 ERC20 Dart 上创建 USDT 钱包

Question

我想自己了解如何用飞镖语言生成 USDT ERC20 钱包。我找到了web3dart 库。但是，使用bip39 库提供的 12 词短语生成 koschel 需要什么？而且我不明白，有必要写智能合约吗？我想看一个如何生成钱包的小代码示例。非常感谢。

更新：

我似乎设法生成了一个钱包。但是如何在 ERC20 上准确地制作 USDT？

var random = Random.secure();
var mnemonic = 'obvious width mechanic wheat cargo toe bike seek spirit jungle enlist thumb';
String mnemonicToSeedHex = bip39.mnemonicToSeedHex(mnemonic);
EthPrivateKey credentials = EthPrivateKey.fromHex(mnemonicToSeedHex);
Wallet wallet = Wallet.createNew(credentials, mnemonic, random);
var address = await credentials.extractAddress();
dev.log(address.hex);

Answer 1

由于USDT是erc-20代币，您可以使用erc-20 abi进行合约交互。

final _erc20ContractAbi = web3.ContractAbi.fromJson(
        '[{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"owner","type":"address"},{"indexed":true,"internalType":"address","name":"spender","type":"address"},{"indexed":false,"internalType":"uint256","name":"value","type":"uint256"}],"name":"Approval","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"from","type":"address"},{"indexed":true,"internalType":"address","name":"to","type":"address"},{"indexed":false,"internalType":"uint256","name":"value","type":"uint256"}],"name":"Transfer","type":"event"},{"inputs":[{"internalType":"address","name":"owner","type":"address"},{"internalType":"address","name":"spender","type":"address"}],"name":"allowance","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"spender","type":"address"},{"internalType":"uint256","name":"amount","type":"uint256"}],"name":"approve","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"account","type":"address"}],"name":"balanceOf","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"decimals","outputs":[{"internalType":"uint8","name":"","type":"uint8"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"name","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"symbol","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"totalSupply","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"recipient","type":"address"},{"internalType":"uint256","name":"amount","type":"uint256"}],"name":"transfer","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"sender","type":"address"},{"internalType":"address","name":"recipient","type":"address"},{"internalType":"uint256","name":"amount","type":"uint256"}],"name":"transferFrom","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"nonpayable","type":"function"}]',
        'Erc20');

现在编写一个类来与 abi 中的每个函数进行交互。您需要传递合约地址、web3client（infura 或任何其他）和 chainID（以太坊主网为 1）

class ERC20 extends web3.GeneratedContract {
  ERC20({
    required web3.EthereumAddress address,
    required web3.Web3Client client,
    int? chainId,
  }) : super(web3.DeployedContract(_erc20ContractAbi, address), client,
            chainId);

现在你可以像这样在类中编写 balanceOf 方法来获取你的 USDT 余额，

Future<BigInt> balanceOf(
    web3.EthereumAddress account, {
    web3.BlockNum? atBlock,
  }) async {
    final function = self.abi.functions[2];
    assert(checkSignature(function, '70a08231'));
    final params = [account];
    final response = await read(function, params, atBlock);
    return (response[0] as BigInt);
  }

转入USDT代币的功能，

Future<String> transfer(
    web3.EthereumAddress recipient,
    BigInt amount, {
    required web3.Credentials credentials,
    web3.Transaction? transaction,
  }) async {
    final function = self.abi.functions[7];
    assert(checkSignature(function, 'a9059cbb'));
    final params = [recipient, amount];
    return write(credentials, transaction, function, params);
  }

查看我在 Medium 上的文章 Crypto-wallet app using flutter，了解如何构建自己的 erc-20 代币并使用 Flutter 移动应用构建可以转移代币的钱包。