Spring Boot集成BlockChain快速入门Demo

1.什么是区块链？

区块链定义： 区块链是一个共享的、不可篡改的账本，旨在促进业务网络中的交易记录和资产跟踪流程。资产可以是有形的（如房屋、汽车、现金、土地），也可以是无形的（如知识产权、专利、版权、品牌）。几乎任何有价值的东西都可以在区块链网络上跟踪和交易，从而降低各方面的风险和成本。 **为什么区块链很重要：**业务运营依靠信息。信息接收速度越快，内容越准确，越有利于业务运营。区块链是用于传递这些信息的理想之选，因为它可提供即时、共享和完全透明的信息，这些信息存储在不可篡改的账本上，只能由获得许可的网络成员访问。区块链网络可跟踪订单、付款、帐户、生产等信息。由于成员之间共享单一可信视图，因此，您可采取端到端方式查看交易的所有细节，从而增强信心，提高效率并获得更多的新机会。

区块链的关键元素

分布式分类账技术：所有网络参与者都可以访问分布式分类账及其不可篡改的交易记录。借助这种共享分类账，交易只记录一次，可消除传统业务网络典型的重复工作。
不可篡改记录：交易记录至共享分类账后，任何参与者都不能更改或篡改交易。如果交易记录中包含错误，则必须添加新交易来撤销错误，然后两笔交易均可见。
智能合约：为了加快交易速度，区块链上存储并自动运行了一组称为智能合约的规则。智能合约可定义企业债券转让的条件，包括支付旅行保险的条款等等。

区块链如何运作

每笔交易发生时，都会记录为一个数据"区块"

这些交易表明资产的流动，资产可以是有形的（产品），也可以是无形的（知识）。数据区块可以记录您选择的信息：人物、事件、时间、地点、价格。它甚至可以记录条件，例如食品运输温度。

每个区块都与其前后的区块相连

随着资产从一地转移至另一地，或所有权易手，这些区块会形成数据链。区块可确认交易的准确时间和顺序，并且区块之间安全地链接在一起，以防止任何区块遭到篡改，或在两个现有区块之间插入一个其他区块。

交易以区块形式组合在一条不可逆的链中：区块链

每添加一个区块都会加强对前一个区块的验证，从而加强整条区块链的验证。区块链篡改会变得容易发现，这就是不可篡改性的关键优势。这可以消除恶意行为者进行篡改的可能性，并建立您预其他网络成员可以信任的交易分类账。

2.环境搭建

Deploy a Custom Ethereum Network

docker run -d --name ethereum -p 8545:8545 -p 30303:30303 ethereum/client-go --http --http.addr="0.0.0.0" --http.api="db,eth,net,web3,personal" --http.corsdomain="*" --dev

view logs

docker logs -f ethereum

Create Account

docker exec -it ethereum geth attach ipc:/tmp/geth.ipc

Welcome to the Geth JavaScript console!

instance: Geth/v1.10.15-unstable-356bbe34/linux-amd64/go1.17.5
coinbase: 0x40f074a6c0e40f7c5167718355375c6f2c509690
at block: 0 (Thu Jan 01 1970 00:00:00 GMT+0000 (UTC))
 datadir:
 modules: admin:1.0 clique:1.0 debug:1.0 eth:1.0 miner:1.0 net:1.0 personal:1.0 rpc:1.0 txpool:1.0 web3:1.0

To exit, press ctrl-d or type exit
> personal.newAccount('ABC')
"0x9b418710ce8438e5fe585b519e8d709e1ea77aca"
> eth.accounts
["0x40f074a6c0e40f7c5167718355375c6f2c509690", "0x9b418710ce8438e5fe585b519e8d709e1ea77aca"]

Send Ethers to Accounts

> eth.sendTransaction({from: eth.accounts[0], to: eth.accounts[1], value: web3.toWei(100000, 'ether')})
"0x48fe4bd2d6db424ecc1f3713809d53e103fa7fc63646f4051a6a280d5f7080ea"
> eth.getBalance(eth.accounts[1])

3.代码工程

实验目标

使用Java对接ethereum网络

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>springboot-demo</artifactId>
        <groupId>com.et</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>Blockchain</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <dependencies>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.web3j</groupId>
            <artifactId>core</artifactId>
            <version>4.0.1</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.9.4</version>
        </dependency>
        <dependency>
            <groupId>org.ethereum</groupId>
            <artifactId>solcJ-all</artifactId>
            <version>0.4.25</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.2</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>
    <build>
    <plugins>
        <plugin>
            <groupId>org.web3j</groupId>
            <artifactId>web3j-maven-plugin</artifactId>
            <version>0.3.7</version>
            <configuration>
                <packageName>org.sgitario.lottery.blockchain.model</packageName>
                <nativeJavaType>true</nativeJavaType>
                <outputFormat>java,bin,abi</outputFormat>
                <soliditySourceFiles>
                    <directory>src/main/resources/contracts</directory>
                    <includes>
                        <include>*.sol</include>
                    </includes>
                </soliditySourceFiles>
                <outputDirectory>
                    <java>src/main/java</java>
                    <bin>src/main/resources/bin/generated</bin>
                    <abi>src/main/resources/abi/generated</abi>
                </outputDirectory>
            </configuration>
        </plugin>
    </plugins>
    </build>
    <repositories>

        <repository>
            <id>nexus-ethereum</id>
            <name>Nexus ethereum</name>
            <layout>default</layout>
            <url>https://dl.bintray.com/ethereum/maven/</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
            <releases>
                <enabled>true</enabled>
            </releases>
        </repository>
    </repositories>
</project>

controller

package com.et.bc.controller;

import com.et.bc.model.Balance;
import com.et.bc.service.LotteryService;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.web3j.protocol.Web3j;
import org.web3j.protocol.core.DefaultBlockParameterName;
import org.web3j.protocol.core.methods.response.EthGetBalance;

import java.io.IOException;
import java.util.List;

@RestController
public class OwnerController {

    @Value("${lottery.contract.owner-address}")
    private String ownerAddress;

    @Autowired
    private Web3j web3j;

    @Autowired
    private LotteryService lotteryService;

    @GetMapping("/owner")
    public String getAddress() {
        return ownerAddress;
    }

    @GetMapping("/owner/balance")
    public Balance getBalance() throws IOException {
        EthGetBalance wei = web3j.ethGetBalance(ownerAddress, DefaultBlockParameterName.LATEST).send();

        return new Balance(wei.getBalance());
    }

    @GetMapping("/owner/lottery/players")
    public List<String> getPlayers() throws Exception {
        return lotteryService.getPlayers(ownerAddress);
    }

    @GetMapping("/owner/lottery/pickWinner")
    public void pickWinner() throws Exception {
        lotteryService.pickWinner(ownerAddress);
    }
}

service

package com.et.bc.service;

import com.et.bc.model.Lottery;
import com.et.bc.model.Player;
import com.et.bc.properties.LotteryProperties;
import org.web3j.protocol.Web3j;
import org.web3j.protocol.core.DefaultBlockParameterName;
import org.web3j.tx.ClientTransactionManager;
import org.web3j.tx.TransactionManager;
import org.web3j.utils.Convert;
import org.web3j.utils.Convert.Unit;

import java.io.IOException;
import java.math.BigInteger;
import java.util.List;

public class LotteryService {

    private final String contractAddress;
    private final Web3j web3j;
    private final LotteryProperties config;

    public LotteryService(String contractAddress, Web3j web3j, LotteryProperties config) {
        this.contractAddress = contractAddress;
        this.web3j = web3j;
        this.config = config;
    }

    public BigInteger getBalance() throws IOException {
        return web3j.ethGetBalance(contractAddress, DefaultBlockParameterName.LATEST).send().getBalance();
    }

    public void join(Player player) throws Exception {
        Lottery lottery = loadContract(player.getAddress());
        lottery.enter(Convert.toWei(player.getEthers(), Unit.ETHER).toBigInteger()).send();
    }

    @SuppressWarnings("unchecked")
    public List<String> getPlayers(String ownerAddress) throws Exception {
        Lottery lottery = loadContract(ownerAddress);
        return lottery.getPlayers().send();
    }

    public void pickWinner(String ownerAddress) throws Exception {
        Lottery lottery = loadContract(ownerAddress);
        lottery.pickWinner().send();
    }

    private Lottery loadContract(String accountAddress) {
        return Lottery.load(contractAddress, web3j, txManager(accountAddress), config.gas());
    }

    private TransactionManager txManager(String accountAddress) {
        return new ClientTransactionManager(web3j, accountAddress);
    }
}

转换器

package com.et.bc.utils;

import org.web3j.utils.Convert;
import org.web3j.utils.Convert.Unit;

import java.math.BigDecimal;
import java.math.BigInteger;

public class ConvertUtils {
    public static BigDecimal toEther(BigInteger wei) {
        return Convert.fromWei(new BigDecimal(wei), Unit.ETHER);
    }
}

注入的属性文件

package com.et.bc.properties;

import lombok.Getter;
import lombok.Setter;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;
import org.web3j.tx.gas.StaticGasProvider;

import java.math.BigInteger;

@Configuration
@ConfigurationProperties(prefix = "lottery.contract")
@Getter
@Setter
public class LotteryProperties {
    private BigInteger gasPrice;
    private BigInteger gasLimit;

    public StaticGasProvider gas() {
        return new StaticGasProvider(gasPrice, gasLimit);
    }
}

配置类

package com.et.bc.config;

import com.et.bc.model.Lottery;
import com.et.bc.properties.LotteryProperties;
import com.et.bc.service.LotteryService;
import okhttp3.OkHttpClient;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.util.StringUtils;
import org.web3j.protocol.Web3j;
import org.web3j.protocol.http.HttpService;
import org.web3j.tx.ClientTransactionManager;
import org.web3j.tx.TransactionManager;

@Configuration
public class LotteryConfiguration {

    private static final Logger LOG = LoggerFactory.getLogger(LotteryConfiguration.class);

    @Value("${lottery.contract.owner-address}")
    private String ownerAddress;

    @Value("${web3j.client-address}")
    private String clientAddress;

    @Autowired
    private LotteryProperties config;

    @Bean
    public Web3j web3j() {
        return Web3j.build(new HttpService(clientAddress, new OkHttpClient.Builder().build()));
    }

    @Bean
    public LotteryService contract(Web3j web3j, @Value("${lottery.contract.address:}") String contractAddress)
            throws Exception {
        if (StringUtils.isEmpty(contractAddress)) {
            Lottery lottery = deployContract(web3j);
            return initLotteryService(lottery.getContractAddress(), web3j);
        }

        return initLotteryService(contractAddress, web3j);
    }

    private LotteryService initLotteryService(String contractAddress, Web3j web3j) {
        return new LotteryService(contractAddress, web3j, config);
    }

    private Lottery deployContract(Web3j web3j) throws Exception {
        LOG.info("About to deploy new contract...");
        Lottery contract = Lottery.deploy(web3j, txManager(web3j), config.gas()).send();
        LOG.info("Deployed new contract with address '{}'", contract.getContractAddress());
        return contract;
    }

    private TransactionManager txManager(Web3j web3j) {
        return new ClientTransactionManager(web3j, ownerAddress);
    }

}

application.properties

web3j.client-address=http://localhost:8545

lottery.contract.owner-address=0x9b418710ce8438e5fe585b519e8d709e1ea77aca

lottery.contract.gas-price=1
lottery.contract.gas-limit=2000000
lottery.contract.address=0x1c0fe20304e76882fe7ce7bb3e2e63dc92ce64de

以上只是一些关键代码，所有代码请参见下面代码仓库

代码仓库

GitHub - Harries/springboot-demo: a simple springboot demo with some components for example: redis,solr,rockmq and so on.

4.测试

启动Spring Boot应用
访问接口http://127.0.0.1:8080/owner
访问接口http://127.0.0.1:8080/owner/balance