51工具盒子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
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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。
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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。
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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
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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。
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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。
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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/go1.17.5coinbase: 0x40f074a6c0e40f7c5167718355375c6f2c509690at 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;
@RestControllerpublic 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@Setterpublic 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;
@Configurationpublic 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=1lottery.contract.gas-limit=2000000lottery.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
- https://github.com/Harries/springboot-demo
4.测试
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启动Spring Boot应用
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访问接口http://127.0.0.1:8080/owner
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访问接口http://127.0.0.1:8080/owner/balance
5.引用
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https://www.ibm.com/cn-zh/topics/blockchain
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http://www.liuhaihua.cn/archives/710788.html
