ETH開發3——以太坊編程接口Web3.js

在進行網站或客戶端開發時，就需要用到web3.js。web3.js庫是一個javascript庫，可以讓你執行很多與區塊鏈進行交互的任務。與Ajax類似，可以使用Web3.js讀寫以太坊區塊鏈。

區塊鏈網絡是一個點對點的對等網絡，網絡由各個節點相互連接構成，智能合約的代碼與數據存儲在區塊鏈中。使用web3.js可以向區塊鏈網絡中某個以太坊節點發出請求，與區塊鏈網絡進行交互。

web3.js使用JSON RPC與Ethereum區塊鏈通信(JSON RPC即JSON遠程調用)，對區塊鏈網絡進行數據讀寫。這有點像使用jQuery ajax庫來讀寫web服務器上的數據。

這里記錄一下Web3.js的常用操作。

一、通過npm安裝

npm install --save web3@0.20

有了這個Web3以太坊編程接口，就可以與以太坊主網進行通信。

二、訪問節點

const Web3 = require('web3')
const rpcURL = '' // RPC URL
const web3 = new Web3(rpcURL)
const address = '' // 賬戶地址
// 讀取address中的余額，余額單位是wei
web3.eth.getBalance(address, (err, wei) => {
    // 余額單位從wei轉換為ether
    balance = web3.utils.fromWei(wei, 'ether')
    console.log("balance: " + balance)
})

三、調用讀取智能合約

const Web3 = require('web3')
const rpcURL = '' // Your RCP URL goes here
const web3 = new Web3(rpcURL)

const abi = [{"constant":true,"inputs":[],"name":"mintingFinished","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_value","type":"uint256"}],"name":"approve","outputs":[],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"_from","type":"address"},{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transferFrom","outputs":[],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[],"name":"unpause","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_amount","type":"uint256"}],"name":"mint","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"paused","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"balanceOf","outputs":[{"name":"balance","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[],"name":"finishMinting","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":false,"inputs":[],"name":"pause","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"owner","outputs":[{"name":"","type":"address"}],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transfer","outputs":[],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_amount","type":"uint256"},{"name":"_releaseTime","type":"uint256"}],"name":"mintTimelocked","outputs":[{"name":"","type":"address"}],"payable":false,"type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"},{"name":"_spender","type":"address"}],"name":"allowance","outputs":[{"name":"remaining","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"newOwner","type":"address"}],"name":"transferOwnership","outputs":[],"payable":false,"type":"function"},{"anonymous":false,"inputs":[{"indexed":true,"name":"to","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Mint","type":"event"},{"anonymous":false,"inputs":[],"name":"MintFinished","type":"event"},{"anonymous":false,"inputs":[],"name":"Pause","type":"event"},{"anonymous":false,"inputs":[],"name":"Unpause","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"owner","type":"address"},{"indexed":true,"name":"spender","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Approval","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"from","type":"address"},{"indexed":true,"name":"to","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Transfer","type":"event"}]
const address = '0xd26114cd6EE289AccF82350c8d8487fedB8A0C07'
const contract = new web3.eth.Contract(abi, address)

contract.methods.totalSupply().call((err, result) => { console.log(result) })
contract.methods.name().call((err, result) => { console.log(result) })
contract.methods.symbol().call((err, result) => { console.log(result) })
contract.methods.balanceOf('0xd26114cd6EE289AccF82350c8d8487fedB8A0C07').call((err, result) => { console.log(result) })

四、准備賬號

> node
> web3.eth.accounts.create()
Thrown:
ReferenceError: web3 is not defined
> const Web3 = require('web3')
undefined
> const web3 = new Web3('https://ropsten.infura.io/v3/YOUR_INFURA_API_KEY')
undefined
> web3.eth.accounts.create()
{ address: '0xf4Ab5314ee8d7AA0eB00b366c52cEEccC62d6B4B',
  privateKey:
   '0xb75e2bcaec74857cf9bb6636d66a04784d4c0fcfd908f4a2bc213428eba5af0d',
  signTransaction: [Function: signTransaction],
  sign: [Function: sign],
  encrypt: [Function: encrypt] }
> web3.eth.accounts.create()
{ address: '0xff96B8B43ECd6C49805747F94747bFfa3A960b69',
  privateKey:
   '0xac0adfdbaeb0770a479e79aac78779d82fdc2f9262e0c8f751ae70fb63ef6196',
  signTransaction: [Function: signTransaction],
  sign: [Function: sign],
  encrypt: [Function: encrypt] }
>

五、執行交易

var Tx     = require('ethereumjs-tx').Transaction
const Web3 = require('web3')
const web3 = new Web3('https://ropsten.infura.io/v3/YOUR_INFURA_API_KEY')

const account1 = '0xf4Ab5314ee8d7AA0eB00b366c52cEEccC62d6B4B' // Your account address 1
const account2 = '0xff96B8B43ECd6C49805747F94747bFfa3A960b69' // Your account address 2

const pk1 = 'b75e2bcaec74857cf9bb6636d66a04784d4c0fcfd908f4a2bc213428eba5af0d' // 實際項目中應該從process.env.PRIVATE_KEY_1中讀取
const pk2 = 'ac0adfdbaeb0770a479e79aac78779d82fdc2f9262e0c8f751ae70fb63ef6196' // 實際項目中應該從process.env.PRIVATE_KEY_2中讀取

const privateKey1 = Buffer.from(pk1, 'hex')
const privateKey2 = Buffer.from(pk2, 'hex')

web3.eth.getTransactionCount(account1, (err, txCount) => {
  // 創建交易對象
  const txObject = {
    nonce:    web3.utils.toHex(txCount),
    to:       account2,
    value:    web3.utils.toHex(web3.utils.toWei('0.1', 'ether')),
    gasLimit: web3.utils.toHex(21000),
    gasPrice: web3.utils.toHex(web3.utils.toWei('10', 'gwei'))
  }

  // 簽署交易
  const tx = new Tx(txObject, { chain: 'ropsten', hardfork: 'petersburg' })
  tx.sign(privateKey1)

  const serializedTx = tx.serialize()
  const raw = '0x' + serializedTx.toString('hex')

  // 廣播交易
  web3.eth.sendSignedTransaction(raw, (err, txHash) => {
    console.log('txHash:', txHash)
    // 可以去ropsten.etherscan.io查看交易詳情
  })
})

 

六、執行部署

var Tx     = require('ethereumjs-tx').Transaction
const Web3 = require('web3')
const web3 = new Web3('https://ropsten.infura.io/v3/YOUR_INFURA_API_KEY')

const account1 = '0xf4Ab5314ee8d7AA0eB00b366c52cEEccC62d6B4B' // Your account address 1
const account2 = '0xff96B8B43ECd6C49805747F94747bFfa3A960b69' // Your account address 2

const pk1 = 'b75e2bcaec74857cf9bb6636d66a04784d4c0fcfd908f4a2bc213428eba5af0d' // 實際項目中應該從process.env.PRIVATE_KEY_1中讀取
const pk2 = 'ac0adfdbaeb0770a479e79aac78779d82fdc2f9262e0c8f751ae70fb63ef6196' // 實際項目中應該從process.env.PRIVATE_KEY_2中讀取

const privateKey1 = Buffer.from(pk1, 'hex')
const privateKey2 = Buffer.from(pk2, 'hex')

web3.eth.getTransactionCount(account1, (err, txCount) => {

  const data = "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"

  // 創建交易對象
  const txObject = {
    nonce:    web3.utils.toHex(txCount),
    gasLimit: web3.utils.toHex(1000000),
    gasPrice: web3.utils.toHex(web3.utils.toWei('10', 'gwei')),
    data: data
  }

  // 簽署交易
  const tx = new Tx(txObject, { chain: 'ropsten', hardfork: 'petersburg' })
  tx.sign(privateKey1)

  const serializedTx = tx.serialize()
  const raw = '0x' + serializedTx.toString('hex')

  // 廣播交易
  web3.eth.sendSignedTransaction(raw, (err, txHash) => {
    console.log('txHash:', txHash)
    // 可以去ropsten.etherscan.io查看交易詳情
  })
})

 七、執行寫函數調用

var Tx     = require('ethereumjs-tx').Transaction
const Web3 = require('web3')
const web3 = new Web3('https://ropsten.infura.io/v3/YOUR_INFURA_API_KEY')

const account1 = '0xf4Ab5314ee8d7AA0eB00b366c52cEEccC62d6B4B' // Your account address 1
const account2 = '0xff96B8B43ECd6C49805747F94747bFfa3A960b69' // Your account address 2

const pk1 = 'b75e2bcaec74857cf9bb6636d66a04784d4c0fcfd908f4a2bc213428eba5af0d' // 實際項目中應該從process.env.PRIVATE_KEY_1中讀取
const pk2 = 'ac0adfdbaeb0770a479e79aac78779d82fdc2f9262e0c8f751ae70fb63ef6196' // 實際項目中應該從process.env.PRIVATE_KEY_2中讀取

const privateKey1 = Buffer.from(pk1, 'hex')
const privateKey2 = Buffer.from(pk2, 'hex')

// 讀取已部署的契約 -- 從Etherscan獲取地址
const contractAddress = '0x30951343d6d80d2c94897f1a81c53cc030aef879'
const contractABI = [
    {
        "constant": false,
        "inputs": [
            {
                "internalType": "string",
                "name": "_value",
                "type": "string"
            }
        ],
        "name": "set",
        "outputs": [],
        "payable": false,
        "stateMutability": "nonpayable",
        "type": "function"
    },
    {
        "constant": true,
        "inputs": [],
        "name": "get",
        "outputs": [
            {
                "internalType": "string",
                "name": "",
                "type": "string"
            }
        ],
        "payable": false,
        "stateMutability": "view",
        "type": "function"
    },
    {
        "inputs": [],
        "payable": false,
        "stateMutability": "nonpayable",
        "type": "constructor"
    }
]

const contract = new web3.eth.Contract(contractABI, contractAddress)

web3.eth.getTransactionCount(account1, (err, txCount) => {

  // 創建交易對象
  const txObject = {
    nonce:    web3.utils.toHex(txCount),
    gasLimit: web3.utils.toHex(8000000),
    gasPrice: web3.utils.toHex(web3.utils.toWei('10', 'gwei')),
    to: contractAddress,
    data: contract.methods.set("qikegu").encodeABI()
  }

  // 簽署交易
  const tx = new Tx(txObject, { chain: 'ropsten', hardfork: 'petersburg' })
  tx.sign(privateKey1)

  const serializedTx = tx.serialize()
  const raw = '0x' + serializedTx.toString('hex')

  // 廣播交易
  web3.eth.sendSignedTransaction(raw, (err, txHash) => {
    console.log('txHash:', txHash)
    // 可以去ropsten.etherscan.io查看交易詳情
  })

})

八、獲取事件

// 獲取事件
contract.getPastEvents(
  'AllEvents',
  {
    fromBlock: 8717848,
    toBlock: 'latest'
  },
).then(function(events) {
    console.log(events)
});

九、區塊查詢

web3.eth.getBlockNumber().then(console.log)
// 查詢最新區塊
web3.eth.getBlock('latest').then(console.log)
// 查詢某個區塊中的指定交易信息
const hash = '0x66b3fd79a49dafe44507763e9b6739aa0810de2c15590ac22b5e2f0a3f502073'
web3.eth.getTransactionFromBlock(hash, 2).then(console.log)

十、常用工具操作

// 根據最近幾個區塊，計算平均Gas價格
web3.eth.getGasPrice().then((result) => {
    console.log("wei: " + result)
    console.log("ether: " + web3.utils.fromWei(result, 'ether'))
})
//評估Gas費
web3.eth.estimateGas({
    to: "0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe",
    data: "0xc6888fa10000000000000000000000000000000000000000000000000000000000000003"
})
.then(console.log);

這個文檔可以的，web3.js – 智能合約對象 | 奇客谷教程 💯 (qikegu.com)