springboot web3js 的使用

搜索了很多内容，发现目前很多文章还在引入
1.6.0 版本，这里版本早已更新，虽然release还没有
https://github.com/web3j/web3j-spring-boot-starter

更多信息
http://docs.web3j.io/4.8.7/references/developer_guide/

Maven 依赖

    
      org.web3j
      web3j-spring-boot-starter
      4.0.3
    
    
    
      org.web3j
      core
      5.0.0
    
    
    
      com.squareup.okhttp3
      okhttp
      4.3.1
    
    

    
      
        org.web3j
        web3j-maven-plugin
        4.8.7
        
          
        
      

使用

环境准备

1. ganache
2. metamask
3. 自己搭建的私有链（可选）基于docker的以太坊集群的私有链开发环境

代码仓库

https://gitee.com/simonzz/springboot-web3js-demo.git

• 追加bean

  @Bean
  public Web3j web3j() {
    String ip  = "http://localhost:9545";
    OkHttpClient.Builder builder = new OkHttpClient().newBuilder();
    builder.connectTimeout(30*1000, TimeUnit.MILLISECONDS);
    builder.writeTimeout(30*1000, TimeUnit.MILLISECONDS);
    builder.readTimeout(30*1000, TimeUnit.MILLISECONDS);
    OkHttpClient httpClient = builder.build();
    return Web3j.build(new HttpService(ip,httpClient,false));
  }

• 使用

# 注入 Web3j
  @Autowired
  private Web3j web3j;
# demo 公私钥，可在ganache中取得
  private String fromAddr = "0x9bB1BB52f78B4AA7d913D3afA9F64565407F8103";
  private String fromPrivateKey = "5ee21f66d20976a428e7cd242df1d7775eca1179ad0df6530f7a0ed00f15ac3d";
  private String toAddr = "0xd59728Da828F587196c8e5d58437C7c76c6Fc888";

• 获取GasPrice,价格是以Wei为单位计算的

  public BigInteger getGasPrice() throws IOException {
    EthGasPrice ethGasPrice = web3j.ethGasPrice().send();
    BigInteger gasFee = ethGasPrice.getGasPrice();
    log.info("web3 ethGasPrice: {}", ethGasPrice.getGasPrice().longValue());
    return gasFee;
  }

• 获取公钥资产余额

  public BigInteger getBalance(String fromAddr) throws IOException {
    EthGetBalance ethGetBalance = web3j.ethGetBalance(fromAddr, DefaultBlockParameterName.LATEST)
        .send();
    BigInteger balance = ethGetBalance.getBalance();
    log.info("web3 balance: {}", balance.longValue());
    return balance;
  }

• 获取随机数nonce

  public BigInteger getNonce(String fromAddr) throws IOException {
    EthGetTransactionCount transactionCount = web3j
        .ethGetTransactionCount(fromAddr, DefaultBlockParameterName.LATEST).send();
    BigInteger nonce = transactionCount.getTransactionCount();
    log.info("web3 nonce:{}", nonce.longValue());
    return nonce;
  }

• 创建无签名的transaction

  public void createTransaction(BigDecimal amount) throws IOException {
    BigInteger nonce = getNonce(fromAddr);
    BigInteger ethGasPrice = getGasPrice();
    BigInteger transferAmount = Convert.toWei(amount, Unit.ETHER).toBigInteger();
    log.info("transferAmount:{} = amount:{}", transferAmount, amount);
    Transaction etherTransaction = Transaction
        .createEtherTransaction(fromAddr, nonce, ethGasPrice,
            null, toAddr, transferAmount);
    // 估算gasLimit
    EthEstimateGas ethEstimateGas = web3j.ethEstimateGas(etherTransaction).send();
    log.info("EthEstimateGas: {}", ethEstimateGas.getAmountUsed());
    // 调用查看余额 wei为单位
    BigInteger biBalance = getBalance(fromAddr);
    log.info("balance:{}", biBalance);
    // total amount
    BigInteger totalAmount = transferAmount.add(ethEstimateGas.getAmountUsed());
    log.info("totalAmount:{}", totalAmount);
    if (totalAmount.compareTo(biBalance) >= 0) {
      log.error("余额不足！！");
      return;
    }
    EthSendTransaction send = web3j.ethSendTransaction(etherTransaction).send();
    log.info("no sign result: {}", JSONUtil.toJsonStr(send));

  }

• 发送签名转账

/**
   * 私钥签名转账
   * @param to             接收账户
   * @param transferAmount 转账多少ETH
   * @param privateKey     发起者私钥
   * @param chainId        链ID
   * @throws IOException
   */
  public void signTransactionAndSend(String to,
      BigDecimal transferAmount, String privateKey, Long chainId)
      throws IOException {
    BigInteger nonce = getNonce(fromAddr);
    BigInteger gasPrice = getGasPrice();
    BigInteger gasLimit = Convert.toWei(GAS_LIMIT, Unit.WEI).toBigInteger();
    BigInteger value = Convert.toWei(transferAmount, Unit.ETHER).toBigInteger();
    String txHash = "";
    RawTransaction transaction = RawTransaction
        .createTransaction(nonce, gasPrice, gasLimit, to, value, "");
    // 私钥进行判断 去掉0x
    if (privateKey.startsWith("0x")) {
      privateKey = privateKey.substring(2);
    }

    ECKeyPair ecKeyPair = ECKeyPair.create(new BigInteger(privateKey, 16));
    Credentials credentials = Credentials.create(ecKeyPair);
    byte[] signMessage;
    if (!Objects.isNull(chainId)) {
      signMessage = TransactionEncoder.signMessage(transaction, chainId, credentials);
    } else {
      signMessage = TransactionEncoder.signMessage(transaction, credentials);
    }

    String signData = Numeric.toHexString(signMessage);
    log.info("signData: {}", signData);
    if (!"".equals(signData)) {
      EthSendTransaction send = web3j.ethSendRawTransaction(signData).send();
      log.info("result: {}", JSONUtil.toJsonStr(send));
      txHash = send.getTransactionHash();
    }
    log.info("txHash: {}", txHash);
  }