1 简介

web3j是一个高度模块化,响应式的,类型安全的Java和Android库,可以用于和以太坊网络上的节点以及智能合约进行交互
Web3j使你与以太坊网络进行交互,不需要额外的去写与以太坊平台交互的代码开销。

1.1 特性

  • 完整地实现了Ethereum中HTTP和IPC上的JSON-RPC客户端API
  • 支持ethereum钱包
  • 可以自动生成封装好的Java类型的智能合约(支持Solidity和Truffle定义的格式),可以通过Java代码进行合约的创建,部署,以及调用。
  • 可以添加过滤器的响应式函数API
  • 支持Ethereum Name Service(ENS)
  • 支持个人创建的Ethereum网络和个人的Geth客户端API
  • 支持Alchemy和Infura,所以无需自己运行以太坊客户端
  • 支持ERC20和ERC721 Token标准
  • 包括上述许多场景的全面的集成测试
  • 命令行工具
  • 可适配Android
  • 可以通过web3j-quorm支持JP Morgan的Quorum

1.2 依赖

Web3j具有五个运行时依赖

2 使用SpringBoot+Web3j搭建环境

2.1 Etherum环境

通过Web3j与以太坊进行交互前提条件是需要有Ethereum环境,搭建Ethherum环境可以通过多种方式,本文仅列出常用的两个:

  • Ganache
  • Docker

2.2 新建Springboot项目

首先在https://start.spring.io/ 上面初始化一个Springboot项目,导入Idea,或者直接在Idea上面创建。

2.3 导入Web3j

打开pom.xml文件,添加以下依赖:

        <!-- https://mvnrepository.com/artifact/org.web3j/core -->
        <dependency>
            <groupId>org.web3j</groupId>
            <artifactId>web3j-spring-boot-starter</artifactId>
            <version>4.0.3</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.web3j/core -->
        <dependency>
            <groupId>org.web3j</groupId>
            <artifactId>core</artifactId>
            <version>4.8.4</version>
        </dependency>
        <dependency>
            <groupId>com.squareup.okhttp3</groupId>
            <artifactId>okhttp</artifactId>
            <version>4.3.1</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

2.4 基本配置

接下来打开application.properties文件,添加以下内容:

# 应用名称
spring.application.name=ethereum-client
#访问端口
server.port=8081
#以太坊交互地址 如果以太坊环境搭建在本地就locallhost,否则使用对应的ip地址,端口默认使用8545
web3j.client-address=http://localhost:8545

3 基本使用

必要的配置已完成,接下来可以与Etherum交互了。这里列出常见的几个功能,文章最后给出完整的代码。

3.1 获取最新的区块号

EthBlockNumber ethBlockNumber = web3j.ethBlockNumber().sendAsync().get();
BigInteger blockNumber = ethBlockNumber.getBlockNumber();

3.2 获取所有账户信息

EthAccounts ethAccounts = web3j.ethAccounts().sendAsync().get();
List<String> accounts = ethAccounts.getAccounts();

3.3 查询Gas价格

EthGasPrice ethGasPrice = web3j.ethGasPrice().sendAsync().get();
BigInteger gasPrice = ethGasPrice.getGasPrice();

3.4 获取ChainId

EthChainId ethChainId = web3j.ethChainId().sendAsync().get();
BigInteger chainId = ethChainId.getChainId();

3.5 获取CoinBase

EthCoinbase ethCoinbase = web3j.ethCoinbase().sendAsync().get();
String coinBase = ethCoinbase.getAddress();

3.6 根据区块号获取区块信息

DefaultBlockParameterNumber defaultBlockParameterNumber = new DefaultBlockParameterNumber(blockNumber);
EthBlock ethBlock = web3j.ethGetBlockByNumber(defaultBlockParameterNumber,true).sendAsync().get();
EthBlock.Block block = ethBlock.getBlock();

3.7 根据区块号获取当前区块所有交易信息

DefaultBlockParameterNumber defaultBlockParameterNumber = new DefaultBlockParameterNumber(blockNumber);
EthBlock ethBlock = web3j.ethGetBlockByNumber(defaultBlockParameterNumber,true).sendAsync().get();
List<EthBlock.TransactionResult> transactionResults = ethBlock.getBlock().getTransactions();

3.8 根据交易哈希值获取交易信息

EthTransaction transaction = web3j.ethGetTransactionByHash(txHash).sendAsync().get();
Optional<Transaction> optionalTransaction = transaction.getTransaction();

4 账户相关

还可以通过私钥或者Key文件查询当前账户下的Ether余额。

4.1 查询Ether余额

BigInteger blockNumber = web3j.ethBlockNumber().sendAsync().get().getBlockNumber();
DefaultBlockParameterNumber defaultBlockParameterNumber = new DefaultBlockParameterNumber(blockNumber);
//根据请求参数获取余额
EthGetBalance ethGetBalance  = web3j.ethGetBalance(credentials.getAddress(),defaultBlockParameterNumber).sendAsync().get();

5 源代码

/**
 * @description 获取区块链信息
 * @author newonexd
 * @date 2022/6/22 21:14
 */
@RestController
@RequestMapping("/chainInfo")
public class BlockChainInfoController {

    private static final Logger logger = LoggerFactory.getLogger(BlockChainInfoController.class);


    @Autowired
    private Web3j web3j;

    /**
     * @description 获取最新的区块号
     * @author newonexd
     * @date 2022/6/22 21:11
     *
     * * @return BigInteger
     */
    @GetMapping("/blockNumber")
    public BigInteger doGetLatestBlockNumber()throws Exception{
        EthBlockNumber ethBlockNumber = web3j.ethBlockNumber().sendAsync().get();
        BigInteger blockNumber = ethBlockNumber.getBlockNumber();
        logger.info("BlockNumber: {}",blockNumber);
        return blockNumber;
    }

    /**
     * @description 获取所有账户
     * @author newonexd
     * @date 2022/6/22 21:11
     *
     * * @return List<String>
     */
    @GetMapping("/accounts")
    public List<String> doGetAllAccounts()throws Exception{
        EthAccounts ethAccounts = web3j.ethAccounts().sendAsync().get();
        List<String> accounts = ethAccounts.getAccounts();
        logger.info("Accounts: {}",accounts);
        return accounts;
    }

    /**
     * @description 获取Gas价格
     * @author newonexd
     * @date 2022/6/22 21:11
     *
     * * @return BigInteger
     */
    @GetMapping("/gasPrice")
    public BigInteger doGetEthGasPrice()throws Exception{
        EthGasPrice ethGasPrice = web3j.ethGasPrice().sendAsync().get();
        BigInteger gasPrice = ethGasPrice.getGasPrice();
        logger.info("Ethereum Gas Price: {}",gasPrice);
        return gasPrice;
    }

    /**
     * @description 获取链Id
     * @author newonexd
     * @date 2022/6/22 21:12
     *
     * * @return BigInteger
     */
    @GetMapping("/chainId")
    public BigInteger doGetChainId()throws Exception{
        EthChainId ethChainId = web3j.ethChainId().sendAsync().get();
        BigInteger chainId = ethChainId.getChainId();
        logger.info("Ethereum Chain Id: {}",chainId);
        return chainId;
    }


    /**
     * @description 获取CoinBase
     * @author newonexd
     * @date 2022/6/22 21:12
     *
     * * @return String
     */
    @GetMapping("/coinbase")
    public String doGetCoinBase()throws Exception{
        EthCoinbase ethCoinbase = web3j.ethCoinbase().sendAsync().get();
        String coinBase = ethCoinbase.getAddress();
        logger.info("Ethereum CoinBase Address: {}",coinBase);
        return coinBase;
    }


    /**
     * @description 根据区块号获取区块信息
     * @author newonexd
     * @date 2022/6/22 21:12
     * @param blockNumber  区块号
     * @return String
     */
    @GetMapping("/getBlockInfo")
    public String doGetAll(@RequestParam(value="blockNumber")Long blockNumber)throws Exception{
        DefaultBlockParameterNumber defaultBlockParameterNumber = new DefaultBlockParameterNumber(blockNumber);
        EthBlock ethBlock = web3j.ethGetBlockByNumber(defaultBlockParameterNumber,true).sendAsync().get();
        EthBlock.Block block = ethBlock.getBlock();
        Gson gson = new Gson();
        String info = gson.toJson(block);
        logger.info(info);
        return info;
    }


    /**
     * @description 根据区块号获取所有交易
     * @author newonexd
     * @date 2022/6/22 21:13
     * @param blockNumber 区块号
     * @return String
     */
    @GetMapping("/getTransactionByBlockNumber")
    public String doGetTransactionInfoByBlockNumber(@RequestParam(value="blockNumber")Long blockNumber)throws Exception{
        DefaultBlockParameterNumber defaultBlockParameterNumber = new DefaultBlockParameterNumber(blockNumber);
        EthBlock ethBlock = web3j.ethGetBlockByNumber(defaultBlockParameterNumber,true).sendAsync().get();
        List<EthBlock.TransactionResult> transactionResults = ethBlock.getBlock().getTransactions();
        List<Transaction> txInfos = new ArrayList<>();

        transactionResults.forEach(txInfo->{
            Transaction transaction = (Transaction)txInfo;
            txInfos.add(transaction);
        });
        Gson gson = new Gson();
        String transactionInfo = gson.toJson(txInfos);
        logger.info(transactionInfo);
        return transactionInfo;
    }


    /**
     * @description 根据交易哈希值获取交易信息
     * @author newonexd
     * @date 2022/6/22 21:13
     * @param txHash 交易哈希值
     * @return String
     */
    @GetMapping("/getTransactionInfoByHash")
    public String doGetTransactionInfoByHash(@RequestParam(value="txHash")String txHash)throws Exception{
        EthTransaction transaction = web3j.ethGetTransactionByHash(txHash).sendAsync().get();
        Optional<Transaction> optionalTransaction = transaction.getTransaction();
        StringBuilder txInfo = new StringBuilder();
        if(optionalTransaction.isPresent()){
            Transaction transactionInfo = optionalTransaction.get();
            Gson gson = new Gson();
            txInfo.append(gson.toJson(transactionInfo));
        }
        logger.info(txInfo.toString());
        return txInfo.toString();
    }
}

内容来源于网络如有侵权请私信删除

文章来源: 博客园

原文链接: https://www.cnblogs.com/cbkj-xd/p/16410053.html

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