web3j 操作

版权声明：学习中。。。 https://blog.csdn.net/fangdengfu123/article/details/82181091

获取账户的Nonce

public static BigInteger getNonce(Web3j web3j, String addr) {
        try {
            EthGetTransactionCount getNonce = web3j.ethGetTransactionCount(addr, DefaultBlockParameterName.PENDING).send();

            if (getNonce == null){
                throw new RuntimeException("net error");
            }
            return getNonce.getTransactionCount();
        } catch (IOException e) {
            throw new RuntimeException("net error");
        }
    }

获取ETH余额

public static BigDecimal getBalance(Web3j web3j, String address) {
        try {
            EthGetBalance ethGetBalance = web3j.ethGetBalance(address, DefaultBlockParameterName.LATEST).send();
            return Convert.fromWei(new BigDecimal(ethGetBalance.getBalance()),Convert.Unit.ETHER);
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }

获取代币余额

public static BigInteger getTokenBalance(Web3j web3j, String fromAddress, String contractAddress) {

        String methodName = "balanceOf";
        List<Type> inputParameters = new ArrayList<>();
        List<TypeReference<?>> outputParameters = new ArrayList<>();
        Address address = new Address(fromAddress);
        inputParameters.add(address);

        TypeReference<Uint256> typeReference = new TypeReference<Uint256>() {
        };
        outputParameters.add(typeReference);
        Function function = new Function(methodName, inputParameters, outputParameters);
        String data = FunctionEncoder.encode(function);
        Transaction transaction = Transaction.createEthCallTransaction(fromAddress, contractAddress, data);

        EthCall ethCall;
        BigInteger balanceValue = BigInteger.ZERO;
        try {
            ethCall = web3j.ethCall(transaction, DefaultBlockParameterName.LATEST).send();
            List<Type> results = FunctionReturnDecoder.decode(ethCall.getValue(), function.getOutputParameters());
            balanceValue = (BigInteger) results.get(0).getValue();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return balanceValue;
    }

构造交易

// 构造eth交易
Transaction transaction = Transaction.createEtherTransaction(fromAddr, nonce, gasPrice, null, toAddr, value);
// 构造合约调用交易
Transaction transaction = Transaction.createFunctionCallTransaction(fromAddr, nonce, gasPrice, null, contractAddr, funcABI);

估算手续费上限

public static BigInteger getTransactionGasLimit(Web3j web3j, Transaction transaction) {
        try {
            EthEstimateGas ethEstimateGas = web3j.ethEstimateGas(transaction).send();
            if (ethEstimateGas.hasError()){
                throw new RuntimeException(ethEstimateGas.getError().getMessage());
            }
            return ethEstimateGas.getAmountUsed();
        } catch (IOException e) {
            throw new RuntimeException("net error");
        }
    }

转账ETH

public static String transferETH(Web3j web3j, String fromAddr, String privateKey, String toAddr, BigDecimal amount, String data){
        // 获得nonce
        BigInteger nonce = getNonce(web3j, fromAddr);
        // value 转换
        BigInteger value = Convert.toWei(amount, Convert.Unit.ETHER).toBigInteger();

        // 构建交易
        Transaction transaction = Transaction.createEtherTransaction(fromAddr, nonce, gasPrice, null, toAddr, value);
        // 计算gasLimit
        BigInteger gasLimit = getTransactionGasLimit(web3j, transaction);

        // 查询调用者余额，检测余额是否充足
        BigDecimal ethBalance = getBalance(web3j, fromAddr);
        BigDecimal balance = Convert.toWei(ethBalance, Convert.Unit.ETHER);
        // balance < amount + gasLimit ??
        if (balance.compareTo(amount.add(new BigDecimal(gasLimit.toString()))) < 0) {
            throw new RuntimeException("余额不足，请核实");
        }

        return signAndSend(web3j, nonce, gasPrice, gasLimit, toAddr, value, data, chainId, privateKey);
    }

转账代币

public static String transferToken(Web3j web3j, String fromAddr, String privateKey, String toAddr, String contractAddr, long amount) {

        BigInteger nonce = getNonce(web3j, fromAddr);
        // 构建方法调用信息
        String method = "transfer";

        // 构建输入参数
        List<Type> inputArgs = new ArrayList<>();
        inputArgs.add(new Address(toAddr));
        inputArgs.add(new Uint256(BigDecimal.valueOf(amount).multiply(BigDecimal.TEN.pow(18)).toBigInteger()));

        // 合约返回值容器
        List<TypeReference<?>> outputArgs = new ArrayList<>();

        String funcABI = FunctionEncoder.encode(new Function(method, inputArgs, outputArgs));

        Transaction transaction = Transaction.createFunctionCallTransaction(fromAddr, nonce, gasPrice, null, contractAddr, funcABI);
        RawTransaction rawTransaction = RawTransaction.createTransaction(nonce, gasPrice, null, contractAddr, null, funcABI);

        BigInteger gasLimit = getTransactionGasLimit(web3j, transaction);

        // 获得余额
        BigDecimal ethBalance = getBalance(web3j, fromAddr);
        BigInteger tokenBalance = getTokenBalance(web3j, fromAddr, contractAddr);
        BigInteger balance = Convert.toWei(ethBalance, Convert.Unit.ETHER).toBigInteger();

        if (balance.compareTo(gasLimit) < 0) {
            throw new RuntimeException("手续费不足，请核实");
        }
        if (tokenBalance.compareTo(BigDecimal.valueOf(amount).toBigInteger()) < 0) {
            throw new RuntimeException("代币不足，请核实");
        }

        return signAndSend(web3j, nonce, gasPrice, gasLimit, contractAddr, BigInteger.ZERO, funcABI, chainId, privateKey);
    }

对交易签名，并发送交易

public static String signAndSend(Web3j web3j, BigInteger nonce, BigInteger gasPrice, BigInteger gasLimit, String to, BigInteger value, String data, byte chainId, String privateKey) {
        String txHash = "";
        RawTransaction rawTransaction = RawTransaction.createTransaction(nonce, gasPrice, gasLimit, to, value, data);
        if (privateKey.startsWith("0x")){
            privateKey = privateKey.substring(2);
        }

        ECKeyPair ecKeyPair = ECKeyPair.create(new BigInteger(privateKey, 16));
        Credentials credentials = Credentials.create(ecKeyPair);

        byte[] signMessage;
        if (chainId > ChainId.NONE){
            signMessage = TransactionEncoder.signMessage(rawTransaction, chainId, credentials);
        } else {
            signMessage = TransactionEncoder.signMessage(rawTransaction, credentials);
        }

        String signData = Numeric.toHexString(signMessage);
        if (!"".equals(signData)) {
            try {
                EthSendTransaction send = web3j.ethSendRawTransaction(signData).send();
                txHash = send.getTransactionHash();
                System.out.println(JSON.toJSONString(send));
            } catch (IOException e) {
                throw new RuntimeException("交易异常");
            }
        }
        return txHash;
    }

获取代理额度

public static BigInteger getAllowanceBalance(Web3j web3j, String fromAddr, String toAddr, String contractAddress) {
        String methodName = "allowance";
        List<Type> inputParameters = new ArrayList<>();
        inputParameters.add(new Address(fromAddr));
        inputParameters.add(new Address(toAddr));

        List<TypeReference<?>> outputs = new ArrayList<>();
        TypeReference<Uint256> typeReference = new TypeReference<Uint256>() {
        };
        outputs.add(typeReference);

        Function function = new Function(methodName, inputParameters, outputs);
        String data = FunctionEncoder.encode(function);
        Transaction transaction = Transaction.createEthCallTransaction(fromAddr, contractAddress, data);
        EthCall ethCall;
        BigInteger balanceValue = BigInteger.ZERO;
        try {
            ethCall = web3j.ethCall(transaction, DefaultBlockParameterName.LATEST).send();
            List<Type> result = FunctionReturnDecoder.decode(ethCall.getValue(), function.getOutputParameters());
            balanceValue = (BigInteger) result.get(0).getValue();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return balanceValue;
    }