SpringBoot區塊鏈之以太坊開發（整合Web3j）

時間 2019-11-24

標籤 springboot 區塊之以開發整合 web3j web 欄目 Spring 简体版

原文原文鏈接

最近公司須要ETH兌換功能，ETH轉帳須要區塊打包，這個時候就須要區塊檢測，目前只是簡單整合，後面會將區塊自動檢測代碼上傳致QQ羣對於區塊鏈開發不太熟悉的童鞋，能夠看看：區塊鏈開發（零）如何開始學習以太坊及區塊鏈歡迎你們加企鵝羣一塊兒討論：260532022首先引入一下依賴pom.xml，主要依賴是 org.web3jjava

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.8.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.xiaobin</groupId>
    <artifactId>eth-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>eth-demo</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.web3j</groupId>
            <artifactId>core</artifactId>
            <version>3.4.0</version>
        </dependency>

        <dependency>
            <groupId>com.github.briandilley.jsonrpc4j</groupId>
            <artifactId>jsonrpc4j</artifactId>
            <version>1.4.6</version>
        </dependency>
        <dependency>
            <groupId>com.mashape.unirest</groupId>
            <artifactId>unirest-java</artifactId>
            <version>1.4.9</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>複製代碼

接下來在application.yml文件中配置以太坊節點路徑，這個節點能夠使用測試節點git

spring:
  application:
    name: xiaobin-eth-demo
server:
  port: 8080
web3j:
  client-address: http://localhost:8545複製代碼

再就是須要將Web3j對象交給Spring進行管理github

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;
/**
 * 建立時間： 2019/9/23  23:21
 * 備註：
 * 碼農自學交流小羣：260532022，歡迎你們的加入，分享學習是一件開心事
 **/
@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;
    }
}複製代碼

Controller測試一下web

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;


/**
* 建立時間： 2019/9/23  23:32
* 備註：
* 碼農自學交流小羣：260532022，歡迎你們的加入，分享學習是一件開心事
**/
@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;
    }
}複製代碼

獲取當前以太坊節點高度，訪問結果圖spring

固然還有更多的方法，這裏沒有去測試了，你們有空能夠本身測測哦apache

獲取帳戶的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");
        }
    }複製代碼

獲取ETH餘額

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");
        }
    }複製代碼

獲取代幣餘額

public static BigInteger getTokenBalance(Web3j web3j, String fromAddress, String contractAddress) {

        String methodName = "balanceOf";
        List<Type> inputParameters = new ArrayList<>();
        List<TypeReference<?>> outputParameters = new ArrayList<>();
        Address address = new Address(fromAddress);
        inputParameters.add(address);

        TypeReference<Uint256> typeReference = new TypeReference<Uint256>() {
        };
        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<Type> results = FunctionReturnDecoder.decode(ethCall.getValue(), function.getOutputParameters());
            balanceValue = (BigInteger) results.get(0).getValue();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return balanceValue;
    }複製代碼

轉帳ETH

public static String transferETH(Web3j web3j, String fromAddr, String privateKey, String toAddr, BigDecimal amount, String data){
        // 得到nonce
        BigInteger nonce = getNonce(web3j, fromAddr);
        // value 轉換
        BigInteger value = Convert.toWei(amount, Convert.Unit.ETHER).toBigInteger();

        // 構建交易
        Transaction transaction = Transaction.createEtherTransaction(fromAddr, nonce, gasPrice, null, toAddr, value);
        // 計算gasLimit
        BigInteger gasLimit = getTransactionGasLimit(web3j, transaction);

        // 查詢調用者餘額，檢測餘額是否充足
        BigDecimal ethBalance = getBalance(web3j, fromAddr);
        BigDecimal balance = Convert.toWei(ethBalance, Convert.Unit.ETHER);
        // balance < amount + gasLimit ??
        if (balance.compareTo(amount.add(new BigDecimal(gasLimit.toString()))) < 0) {
            throw new RuntimeException("餘額不足，請覈實");
        }

        return signAndSend(web3j, nonce, gasPrice, gasLimit, toAddr, value, data, chainId, privateKey);
    }複製代碼

對交易簽名，併發送交易

public static String signAndSend(Web3j web3j, BigInteger nonce, BigInteger gasPrice, BigInteger gasLimit, String to, BigInteger value, String data, byte chainId, String privateKey) {
        String txHash = "";
        RawTransaction rawTransaction = RawTransaction.createTransaction(nonce, gasPrice, gasLimit, to, value, data);
        if (privateKey.startsWith("0x")){
            privateKey = privateKey.substring(2);
        }

        ECKeyPair ecKeyPair = ECKeyPair.create(new BigInteger(privateKey, 16));
        Credentials credentials = Credentials.create(ecKeyPair);

        byte[] signMessage;
        if (chainId > 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("交易異常");
            }
        }
        return txHash;
    }複製代碼

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