区块链钱包之创建以太坊离线交易（ETH交易）

Posted 2021-06-02 陳英傑

（一）区块链钱包之生成助记词
（二）区块链钱包之创建钱包地址
（三）区块链钱包之加密算法简介
（四）区块链钱包之创建比特离线交易（BTC交易）
（五）区块链钱包之创建以太坊交易（ETH交易）

导入Gralde依赖：

org.web3j:core:4.6.0-android

我们做BTC和ETH都需要导入库，最终导入如下：

api 'org.bouncycastle:bcpkix-jdk15to18:1.68'
// bouncycastle:bcprov-xxx在web3j和bitcoinj中都有
// api 'org.bouncycastle:bcprov-jdk15to18:1.68'
api group: 'org.bitcoinj', name: 'bitcoinj-core', version: '0.15.10' // 包含org.bouncycastle:bcprov-jdk15to18:1.68
api('org.web3j:core:4.6.0-android') {
    // 剔除 org.bouncycastle:bcprov-jdk15on:1.60
    exclude group: 'org.bouncycastle', module: 'bcprov-jdk15on'
}

创建以太交易如下：

// 首先需要创建凭证：

public Credentials getCredentials(List<String> keywords) {
	Credentials credentials = null;
    WalletAddressModel model = FaxMsnPlugin.getMF().getModel(WalletAddressModel.class);
    List<WalletAddressModel.Item> items = model.findByType(CoinType.ETH.type);
    if (!ArrayUtils.isEmpty(items)) {
       WalletAddressModel.Item item = items.get(0);
       if (item != null) {
          DeterministicKey key = FaxWalletUtils.generateKeyByPath(keywords, item.realPath);
          String privateKeyAsHex = key.getPrivateKeyAsHex();
          credentials = Credentials.create(privateKeyAsHex);
       }
    }
    return credentials;
}

	// 创建一般交易
	public String createTransaction(List<String> keywords, String destinationAddress, long nonce, long gasPrice, long gasLimit, BigDecimal value) {
      String hexStr = "";
      try {
        if (credentials != null) {
          BigInteger nonceBig = BigInteger.valueOf(nonce);
          BigInteger gasPriceBig = BigInteger.valueOf(gasPrice);
          BigInteger gasLimitBig = BigInteger.valueOf(gasLimit);
          RawTransaction transaction = RawTransaction.createEtherTransaction(nonceBig, gasPriceBig, gasLimitBig, destinationAddress, value.toBigInteger());
          byte[] bytes = TransactionEncoder.signMessage(transaction, credentials);
          hexStr = Numeric.toHexStringNoPrefix(bytes);
        }
      } catch (Exception e) {
        e.printStackTrace();
      }
      return hexStr;
	}

	// 根据合约地址创建交易
	public String createContractTransaction(List<String> keywords, String destinationAddress, long nonce, long gasPrice, long gasLimit, BigDecimal value, String contractAddress) {
	      String result = "";
      try {
        if (credentials != null) {
          BigInteger nonceBig = BigInteger.valueOf(nonce);
          BigInteger gasPriceBig = BigInteger.valueOf(gasPrice);
          BigInteger gasLimitBig = BigInteger.valueOf(gasLimit);
          String data = "0xa9059cbb" +
            Numeric.toHexStringNoPrefixZeroPadded(Numeric.toBigInt(destinationAddress), 64) +
            Numeric.toHexStringNoPrefixZeroPadded(value.toBigInteger(), 64);
          RawTransaction transaction = RawTransaction.createTransaction(nonceBig, gasPriceBig, gasLimitBig, contractAddress, data);
          byte[] bytes = TransactionEncoder.signMessage(transaction, credentials);
          result = Numeric.toHexStringNoPrefix(bytes);
        }
      } catch (Exception e) {
        e.printStackTrace();
      }
      return result;
	}

希望我的分享能帮助到大家