以太坊入门（三）用web3j进行以太转账及代币转账

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。