# 以太坊入门（三）用web3j进行以太转账及代币转账

- URL: https://wuming.si/blog/1316/
- Author: Aaron
- Published: 2019-07-01
- Language: zh-Hans
- Categories: Technology
- Originally published at: https://blog.wo.ai/archives/1316

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