分享下web3j 常见用法

转账

fun sendEthTransaction(privateKey: String,toAddress: String,amount: BigDecimal) {//chainIdval chainId:Long = 1//url 可以从https://chainlist.org/里面获取可用节点//eth转账，bnb同理，但需发送到bnb对应节点val url = "https://xxx"val web3j = Web3j.build(HttpService(url))val credentials = Credentials.create(privateKey)val count =web3j.ethGetTransactionCount(credentials.address, DefaultBlockParameterName.LATEST).send()val nonce = count.transactionCountval gasPrice = Convert.toWei("20", Convert.Unit.GWEI).toBigInteger()val gasLimit = BigInteger.valueOf(21000)val value = Convert.toWei(amount, Convert.Unit.ETHER).toBigInteger()val rawTransaction = RawTransaction.createEtherTransaction(nonce, gasPrice, gasLimit, toAddress, value)val signedMessage = TransactionEncoder.signMessage(rawTransaction, chainId,credentials)val hexValue = Numeric.toHexString(signedMessage)logDebug("签名后的数据 $hexValue")val ethSendTransaction = web3j.ethSendRawTransaction(hexValue).send()if (ethSendTransaction.hasError()) {println("发送 ETH 交易时出错: ${ethSendTransaction.error.message}")} else {println("ETH 交易哈希: ${ethSendTransaction.transactionHash}")}}

    fun sendErc20USDTTransaction(privateKey: String,toAddress: String,amount: BigInteger) {//erc20 usdt 合约地址val contractAddress = "0xdAC17F958D2ee523a2206206994597C13D831ec7"val url = "https://xxx"val web3j = Web3j.build(HttpService(url))val credentials = Credentials.create(privateKey)val count = web3j.ethGetTransactionCount(credentials.address, DefaultBlockParameterName.LATEST).send()val nonce = count.transactionCountval gasPrice = Convert.toWei("20", Convert.Unit.GWEI).toBigInteger()val gasLimit = BigInteger.valueOf(200000)val function = Function("transfer",listOf(Address(toAddress), Uint256(amount)),emptyList())val data = FunctionEncoder.encode(function)val rawTransaction = RawTransaction.createTransaction(nonce, gasPrice, gasLimit, contractAddress, data)val signedMessage = TransactionEncoder.signMessage(rawTransaction, credentials)val hexValue = Numeric.toHexString(signedMessage)val ethSendTransaction = web3j.ethSendRawTransaction(hexValue).send()if (ethSendTransaction.hasError()) {println("发送 ERC - 20 代币交易时出错: ${ethSendTransaction.error.message}")} else {println("ERC - 20 代币交易哈希: ${ethSendTransaction.transactionHash}")}}