Tag: 以太坊

上章讲到账户的查询，本章讲述账户转账。

1. 以太坊转账 We3j web3j = Web3j.build(new HttpService(ConstantLibs.WEB3_ADDRESS)); Credentials credentials = WalletTool.loadCredentials(fromAddress); EthGetTransactionCount ethGetTransactionCount = web3j.ethGetTransactionCount( fromAddress, DefaultBlockParameterName.LATEST).sendAsync().get(); BigInteger nonce = ethGetTransactionCount.getTransactionCount(); RawTransaction rawTransaction = RawTransaction.createEtherTransaction( nonce, Convert.toWei("18", Convert.Unit.GWEI).toBigInteger(), Convert.toWei("45000", Convert.Unit.WEI).toBigInteger(), toAddress, new BigInteger(amount)); byte[] signedMessage = TransactionEncoder.signMessage(rawTransaction, credentials); String hexValue = Numeric.toHexString(signedMessage); EthSendTransaction ethSendTransaction = web3.ethSendRawTransaction(hexValue).sendAsync().get(); if (ethSendTransaction.hasError()) { log.info("transfer error:", ethSendTransaction.getError().getMessage()); } else { String transactionHash = ethSendTransaction.getTransactionHash(); log.info("Transfer transactionHash:" + transactionHash); }
2. 以太坊代币转账 Web3j web3j = Web3j.build(new HttpService(ConstantLibs.WEB3_ADDRESS)); Credentials credentials = WalletTool.loadCredentials(fromAddress); EthGetTransactionCount ethGetTransactionCount = web3j.ethGetTransactionCount( fromAddress, DefaultBlockParameterName.LATEST).sendAsync().get(); BigInteger nonce = ethGetTransactionCount.getTransactionCount(); Function function = new Function( "transfer", Arrays.asList(new Address(toAddress), new Uint256(new BigInteger(amount))), Arrays.asList(new TypeReference<Type>() { })); String encodedFunction = FunctionEncoder.encode(function); RawTransaction rawTransaction = RawTransaction.createTransaction(nonce, Convert.toWei("18", Convert.Unit.GWEI).toBigInteger(), Convert.toWei("100000", Convert.Unit.WEI).toBigInteger(), contractAddress, encodedFunction); byte[] signedMessage = TransactionEncoder.signMessage(rawTransaction, credentials); String hexValue = Numeric.toHexString(signedMessage); log.debug("transfer hexValue:" + hexValue); EthSendTransaction ethSendTransaction = web3.ethSendRawTransaction(hexValue).sendAsync().get(); if (ethSendTransaction.hasError()) { log.info("transfer error:", ethSendTransaction.getError().getMessage()); } else { String transactionHash = ethSendTransaction.getTransactionHash(); log.info("Transfer transactionHash:" + transactionHash); }

代币转账和以太转账的区别在于，to地址是合约地址，而input是有三部分数据构成：transfer方法的哈希+收款人的地址+转账金额。此处比较难理解的正是Function部分，设置好参数以后，调用rawTransaction就可以了。

本站始发，转载于 https://www.jianshu.com/p/8ae984e6bafc

以太坊的开发，基本都是go语言和nodejs的天下，web3j出现给java开发人员提供了很大的便利。本文会对一些以太坊的基本操作用java语言来实现。

本章会讲述通过web3j进行账户余额的查询。

1. 以太余额查询
   以太的余额查询比较简单，直接调用web3j的ethGetBalance就可以。 Web3j web3j = Web3j.build(new HttpService(ConstantLibs.WEB3_ADDRESS)); EthGetBalance ethGetBalance = web3j.ethGetBalance( address, DefaultBlockParameterName.LATEST).sendAsync().get(); BigInteger balance = ethGetBalance.getBalance();
2. 通证的余额查询
   代币的查询就比较复杂一些，研究了好长时间，最后发现每个代币合约都会实现balanceOf方法，可以通过这个方法来查询通证的余额。 Web3j web3j = Web3j.build(new HttpService(ConstantLibs.WEB3_ADDRESS)); Function function = new Function( "balanceOf", Arrays.asList(new Address(address)), // Solidity Types in smart contract functions Arrays.asList(new TypeReference<Type>() { })); String encodedFunction = FunctionEncoder.encode(function); org.web3j.protocol.core.methods.response.EthCall response = web3j.ethCall( org.web3j.protocol.core.methods.request.Transaction.createEthCallTransaction(address, contract, encodedFunction), DefaultBlockParameterName.LATEST) .sendAsync().get(); String returnValue = response.getValue(); //返回16进制余额 returnValue = returnValue.substring(2); BigInteger balance = new BigInteger(returnValue, 16);

本站始发，转载于https://www.jianshu.com/p/0f3e65622d65