SpringBoot区块链之以太坊开发（整合Web3j）

最近公司需要ETH兑换功能，ETH转账需要区块打包，这个时候就需要区块检测，目前只是简单整合，后面会将区块自动检测代码上传致QQ群 对于区块链开发不太熟悉的童鞋，可以看看：[区块链开发（零）如何开始学习以太坊及区块链](https://blog.csdn.net/sportshark/article/details/52351415) 欢迎大家加企鹅群一起讨论：260532022 首先引入一下依赖pom.xml，主要依赖是 org.web3j ``` 4.0.0org.springframework.bootspring-boot-starter-parent2.1.8.RELEASEcom.xiaobineth-demo0.0.1-SNAPSHOTeth-demoDemo project for Spring Boot1.8org.springframework.bootspring-boot-starter-weborg.springframework.bootspring-boot-devtoolsruntimetrueorg.projectlomboklomboktrueorg.web3jcore3.4.0com.github.briandilley.jsonrpc4jjsonrpc4j1.4.6com.mashape.unirestunirest-java1.4.9org.springframework.bootspring-boot-starter-testtestorg.springframework.bootspring-boot-maven-plugin ``` 接下来在application.yml文件中配置以太坊节点路径，这个节点可以使用测试节点 ``` spring: application: name: xiaobin-eth-demo server: port: 8080 web3j: client-address: http://localhost:8545 ``` 再就是需要将Web3j对象交给Spring进行管理 ``` package com.xiaobin.ethdemo.config; import com.googlecode.jsonrpc4j.JsonRpcHttpClient; import okhttp3.OkHttpClient; import org.springframework.beans.factory.annotation.Value; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.web3j.protocol.Web3j; import org.web3j.protocol.http.HttpService; import java.net.MalformedURLException; import java.net.URL; import java.util.HashMap; import java.util.Map; import java.util.concurrent.TimeUnit; /** * 创建时间： 2019/9/23 23:21 * 备注： * 码农自学交流小群：260532022，欢迎大家的加入，分享学习是一件开心事 **/ @Configuration public class EthConfig { @Value("${web3j.client-address}") private String rpc; @Bean public Web3j web3j() { OkHttpClient.Builder builder = new OkHttpClient.Builder(); builder.connectTimeout(30*1000, TimeUnit.MILLISECONDS); builder.writeTimeout(30*1000, TimeUnit.MILLISECONDS); builder.readTimeout(30*1000, TimeUnit.MILLISECONDS); OkHttpClient httpClient = builder.build(); Web3j web3j = Web3j.build(new HttpService(rpc,httpClient,false)); return web3j; } } ``` Controller测试一下 ``` package com.xiaobin.ethdemo.controller; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; import org.web3j.protocol.Web3j; import org.web3j.protocol.core.methods.response.EthBlockNumber; /** * 创建时间： 2019/9/23 23:32 * 备注： * 码农自学交流小群：260532022，欢迎大家的加入，分享学习是一件开心事 **/ @RestController @RequestMapping("/eth") public class WalletController { @Autowired private Web3j web3j; @GetMapping("height") public long getHeight() { try { EthBlockNumber blockNumber = web3j.ethBlockNumber().send(); long blockHeight = blockNumber.getBlockNumber().longValue(); return blockHeight; } catch (Exception e) { e.printStackTrace(); } return 0; } } ``` 获取当前以太坊节点高度，访问结果图  当然还有更多的方法，这里没有去测试了，大家有空可以自己测测哦 #### 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 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"); } } ``` #### 获取代币余额 ``` public static BigInteger getTokenBalance(Web3j web3j, String fromAddress, String contractAddress) { String methodName = "balanceOf"; List inputParameters = new ArrayList(); List> outputParameters = new ArrayList(); Address address = new Address(fromAddress); inputParameters.add(address); TypeReference typeReference = new TypeReference() { }; 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 results = FunctionReturnDecoder.decode(ethCall.getValue(), function.getOutputParameters()); balanceValue = (BigInteger) results.get(0).getValue(); } catch (IOException e) { e.printStackTrace(); } return balanceValue; } ``` #### 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 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; } ``` 有什么问题或者缺少什么依赖包，可以加QQ群哦 ###### 码农自学交流小群：260532022，欢迎大家的加入，分享学习是一件开心事