本地开发环境以太坊合约交互实战

操作步骤

所有的操作都是在goland里面使用nodejs调web3库

•编写合约
•编译合约（web3）-用solc编译（拿到bytecode、abi）
•部署合约（web3）
•找到合约实例
•调用合约（set，get操作）

开发环境

//安装淘宝的镜像
npm install -g cnpm --registry=https://registry.npm.taobao.org

//安装指定版本solc
 cnpm install [email protected]

//安装create-react-app
npm install create-react-app -g

//创建空的react项目
create-react-app project

//进入到project中
npm run start

//安装web3
npm i web3 --save

web3模块划分：

•web3-eth：与blockchain合约相关的模块
•web3-shh：与p2p协议广播相关
•web3-bzz：与swarm存储协议相关
•web3-utils：开发者工具相关

a.部署合约时候，需要用到提供abi，即可执行后面的动作，进行部署 b.获取合约实例的时候需要用到这个函数，指定abi，指定address

Ganache用于搭建私有网络。在开发和测试环境下，Ganache提供了非常简便的以太坊私有网络搭建方法，
通过可视化界面可以直观地设置各种参数、浏览查看账户和交易等数据

代码加注解

01-compile

//导入solc编译器
var solc = require('solc')

//读取合约
let fs = require('fs')
let sourceCode = fs.readFileSync('./contracts/SimpleStorage.sol', 'utf-8')


let output = solc.compile(sourceCode, 1)
console.log('output:', output)

console.log('abi:______',output['contracts'][':SimpleStorage']['interface'])

//导出合约
module.exports = output['contracts'][':SimpleStorage']

02-deploy

let {bytecode, interface} = require('./01-compile')

// console.log('bytecode_____',bytecode)
// console.log('interface____',interface)


//1.引入web3

let Web3 = require('web3')

//2.new一个web3实例
let web3 = new Web3()

//3.设置网络
web3.setProvider('http://localhost:7545')

console.log('version:________', web3.version)
console.log('web3-eth.curretProvider_____________', web3.currentProvider)


//此地址需要使用Ganache地址
const account ='0xd4DB91aCBB5Be2a42276567c7473857e14888B53'

//1.拼接合约数据interface
let contract = new web3.eth.Contract(JSON.parse(interface))
//2.拼接bytecode
contract.deploy({
    data: bytecode,//合约的bytecode
    arguments: ['helloworld']//给构造函数传递参数，使用数组
}).send({
    from:account,
    gas:'3000000',
    gasPrice:'1',
}).then(instance =>{
    console.log('address:',instance.options.address)
})

03-instance

//获取合约实例，导出去
//1.引入web3
let Web3 = require('web3')

//2.new一个web3实例
let web3 = new Web3()

//3.设置网络
web3.setProvider('http://localhost:7545')

let abi = [{
    "constant": true,
    "inputs": [],
    "name": "getValue",
    "outputs": [{"name": "", "type": "string"}],
    "payable": false,
    "stateMutability": "view",
    "type": "function"
}, {
    "constant": false,
    "inputs": [{"name": "_str", "type": "string"}],
    "name": "setValue",
    "outputs": [],
    "payable": false,
    "stateMutability": "nonpayable",
    "type": "function"
}, {
    "inputs": [{"name": "_str", "type": "string"}],
    "payable": false,
    "stateMutability": "nonpayable",
    "type": "constructor"
}]
let address = '0x7a0402FDB3de50eBEBe77F0ff72A6b7526e92447' //此处是合约地址
//此处abi已经json对象，不需要进行parse动作
let contractInstance = new web3.eth.Contract(abi, address)
console.log('address__________', contractInstance.options.address)
module.exports = contractInstance

04-interaction

//1.导入合约实例
let instance = require('./03-instance')
const from = '0xd4DB91aCBB5Be2a42276567c7473857e14888B53'

//异步调用，返回值是一个promise
//2.读取数据

//整体封装成函数
//web3和区块链交互的返回值都是promise，可以直接使用async

let test = async () => {

    try {
        let y1 = await instance.methods.getValue().call()

        let res = await instance.methods.setValue('Hello HangTou').send({
            from: from,
            value: 0,
        })

        console.log('res:', res)
        let v2 = await instance.methods.getValue().call()

        console.log('v2:', v2)
    } catch (e) {
        console.log(e)
    }
}

test()

调用结果

git地址 https://github.com/potaxie/web3