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[区块链]Web3js 小笔记

Web3js

区块链是一个由区块组成的列表，这些块的内容基本是交易记录，每个交易都有一个附加的交易日志，事件结果存放在交易日志里。合约发出的时间，可以使用合约地址访问

基本使用

入门认知

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))
console.log(web3)

查看 web3 连接的节点信息

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

web3.eth.getNodeInfo().then(console.log)

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查看是否连接到节点

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

web3.eth.net.isListening().then(console.log)

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获取当前连接网络的 id

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

web3.eth.net.getId().then(console.log)

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Provider 相关

查看当前 web3 provider

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

console.log(web3.currentProvider)

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设置/修改 provider

其实就是临时修改为其他的 provider

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

web3.setProvider(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

批处理

批处理请求就是将几个请求打包在一起提交
可以保证交易顺序

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

var abi = [{
        "inputs": [],
        "name": "getNumber",
        "outputs": [{
            "internalType": "uint256",
            "name": "",
            "type": "uint256"
        }],
        "stateMutability": "view",
        "type": "function"
    },
    {
        "inputs": [{
            "internalType": "uint256",
            "name": "_number",
            "type": "uint256"
        }],
        "name": "setNumber",
        "outputs": [],
        "stateMutability": "nonpayable",
        "type": "function"
    }
]
var address = "0x28A6FDdD4925386A5b5D8e339dF9A073fE8e74A4"

var contract = new web3.eth.Contract(abi, address)

function callback1() {
    console.log("callback run 1")
}

function callback2() {
    console.log("callback run 2")
}

// 创建批处理对象
var batch = new web3.BatchRequest()

// 添加事务
batch.add(web3.eth.getBalance.request('0x9EC38bFa98Ff2AF34081544BE0d1aA9C709D8283', 'latest', function(error, res) {
    if (error) {
        console.log("s")
    }
}))

大数据处理工具

以太坊内部总是以 wei 来表示余额（大整数），只有显示余额的时候，才转换为 ether 或其他单位。JavaScript 中默认的数字精度无法确切地表示 wei

webjs 中，自带 BigNumber 库

1 wei = 10 ^ 8

var BigNumber = require("bignumber.js")
var balance = new BigNumber("111111111111111111111111111111111111111111111111111");
console.log(balance)

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转化为十进制显示出来

默认保留小数点 20 位

var BigNumber = require("bignumber.js")
var balance = new BigNumber("111111111111111111111111111111111111111111111111111");
console.log(balance.toString(10))

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检查参数

var BigNumber = require("bignumber.js")
var balance = new BigNumber("111111111111111111111111111111111111111111111111111");
var number = balance.toString(10)

var res = web3.utils.isBigNumber(number)
console.log(res)

res = web3.utils.isBigNumber(balance)
console.log(res)

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数值转换

wei 是最小的以太单位

console.log(web3.utils.fromWei('1', 'ether'))
console.log(web3.utils.fromWei('1', 'finney'))
console.log(web3.utils.fromWei('1', 'szabo'))
console.log(web3.utils.fromWei('1', 'shannon'))

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将给定的以太金额转换为以 wei 为单位的数值
```
console.log(web3.utils.toWei('1', 'ether'))
console.log(web3.utils.toWei('1', 'finney'))
console.log(web3.utils.toWei('1', 'szabo'))
console.log(web3.utils.toWei('1', 'shannon'))
```
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任意值转换为 16 进制字符串
```
数值字符串将解析为数值
文本字符串将解析为 utf8 字符串
```
```
console.log(web3.utils.toHex('234'))
console.log(web3.utils.toHex(234))
```
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16 进制字符串转化为数值字符串
```
console.log(web3.utils.hexToNumberString('0xea'))
```
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杂七杂八转换
```
console.log(web3.utils.asciiToHex('abcdef'))
console.log(web3.utils.hexToBytes('0x616263ea'))
console.log(web3.utils.bytesToHex([97, 98, 99, 234]))
```
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检查是否为地址
```
console.log(web3.utils.isAddress('0x5B38Da6a701c568545dCfcB03FcB875f56beddC4'))
```
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区块操作

获取最新区块号

web3.eth.getBlockNumber().then(console.log)

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指定块编号或块哈希对应的块

// 最新的块
web3.eth.getBlock('latest').then(console.log)

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指定块的交易信息

web3.eth.getTransactionFromBlock('0x7fd5f696177d03b7dd882a93c18f6cfbe3fac8240f2c98f27c08c4586793e620', 0).then(console.log)

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指定账号发出的交易数量

web3.eth.getBlockTransactionCount('0x7fd5f696177d03b7dd882a93c18f6cfbe3fac8240f2c98f27c08c4586793e620').then(console.log)

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账户相关操作

查询账户个数

返回当前节点控制的账户列表

web3.eth.getAccounts().then(console.log)

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创建账户

web3.eth.personal.newAccount('!@abc').then(console.log)

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获得奖励的账户地址

web3.eth.getCoinbase().then(console.log)

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是否正在挖矿

web3.eth.isMining().then(console.log)

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交易相关

查询余额

获取指定块中特定只能账户地址的余额

web3.eth.getBalance(address [, defaultBlock] [, callback])

defaultBlock：表执行到指定的区块时的余额
- 区块号
- 区块的 hash 值
- 字符串 “earliest”、“latest”、“pending”

web3.eth.getBalance('0x956188a6bD41694BdB13AA5CE168543a03B74770', function(error, result) {
    if (error) {
        console.log("something error.")
    } else {
        var balance = result.toString()
        console.log(web3.utils.fromWei(balance, "ether"))
    }
})

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查询平均 gas 价格

获取当前 gas 价格，该价格由最近的若干块的 gas 价格中值决定

web3.eth.getGasPrice().then(console.log)

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发送交易

var transactionObject = {
    from: '0x956188a6bD41694BdB13AA5CE168543a03B74770',
    to: '0x1a3D5055624707B689CA8130f72Abf41c461344B',
    value: web3.utils.toWei('1', 'ether'),
    data: web3.utils.toHex(234)
}

web3.eth.sendTransaction(transactionObject).then(console.log)

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查询交易信息

web3.eth.getTransaction(transactionHash [, callback])	返回具有指定哈希值的交易对象

transactionHash - 交易哈希

web3.eth.getTransaction('0x11e1559508147c7ea2d3e9ce0dfb65be29d42d7a9077f9cef3e80ad64d38b3b8').then(console.log)

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查询交易收据

也就是进区块数据

web3.eth.getTransactionReceipt(hash [,callback])	返回指定交易的收据对象，如果交易处于 pending 状态，则返回 null

查询已经被打包进区块链的信息

web3.eth.getTransactionReceipt('0x11e1559508147c7ea2d3e9ce0dfb65be29d42d7a9077f9cef3e80ad64d38b3b8').then(console.log)

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与合约交互

ABI 简绍

相当于智能合约暴漏出来的标准接口

调用智能合约读函数

通常使用 call（）

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

var abi = [{
        "inputs": [],
        "name": "getNumber",
        "outputs": [{
            "internalType": "uint256",
            "name": "",
            "type": "uint256"
        }],
        "stateMutability": "view",
        "type": "function"
    },
    {
        "inputs": [{
            "internalType": "uint256",
            "name": "_number",
            "type": "uint256"
        }],
        "name": "setNumber",
        "outputs": [],
        "stateMutability": "nonpayable",
        "type": "function"
    }
]

var contractAddress = '0x4E4861f95f4cB129Dae9E739458f1583E1100Dd1'
var myContract = new web3.eth.Contract(abi, contractAddress)

myContract.methods.getNumber().call(function(error, result) {
    console.log(result)
})

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调用智能合约写函数

调用写函数，相当于发送了交易

myContract.methods.setNumber(1234)
    .send({ from: '0x956188a6bD41694BdB13AA5CE168543a03B74770' })
    .on('receipt', function(receipt) {
        console.log(receipt)
})

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执行事件查询

合约部分

pragma solidity >= 0.7.0 <0.9.0;

contract DemoSimple {
    uint number;

    event myEvent(uint name);

    function setNumber(uint _number) public {
        emit myEvent(_number);
        number = _number;
    }

    function getNumber() public view returns(uint) {
        return number;
    }
}

js 部分

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

var abi = [{
        "anonymous": false,
        "inputs": [{
            "indexed": false,
            "internalType": "uint256",
            "name": "name",
            "type": "uint256"
        }],
        "name": "myEvent",
        "type": "event"
    },
    {
        "inputs": [],
        "name": "getNumber",
        "outputs": [{
            "internalType": "uint256",
            "name": "",
            "type": "uint256"
        }],
        "stateMutability": "view",
        "type": "function"
    },
    {
        "inputs": [{
            "internalType": "uint256",
            "name": "_number",
            "type": "uint256"
        }],
        "name": "setNumber",
        "outputs": [],
        "stateMutability": "nonpayable",
        "type": "function"
    }
]

var contractAddress = '0x9af62672FA2a5f749Df1e3EdCE2A4825Adb73dF2'
var myContract = new web3.eth.Contract(abi, contractAddress)

myContract.getPastEvents(
    'AllEvents', {
        fromBlock: 0,
        toBlock: 'latest'
    },
    (error, result) => { console.log(result) }
)

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手工部署合约

let Web3 = require("web3")
let web3 = new Web3(new Web3.providers.HttpProvider("HTTP://127.0.0.1:8545"))

var abi = [{
        "inputs": [{
            "internalType": "bytes32[]",
            "name": "candidateNames",
            "type": "bytes32[]"
        }],
        "stateMutability": "nonpayable",
        "type": "constructor"
    },
    {
        "inputs": [{
            "internalType": "uint256",
            "name": "",
            "type": "uint256"
        }],
        "name": "candidateList",
        "outputs": [{
            "internalType": "bytes32",
            "name": "",
            "type": "bytes32"
        }],
        "stateMutability": "view",
        "type": "function"
    },
    {
        "inputs": [{
            "internalType": "bytes32",
            "name": "candidate",
            "type": "bytes32"
        }],
        "name": "totalVotesFor",
        "outputs": [{
            "internalType": "uint8",
            "name": "",
            "type": "uint8"
        }],
        "stateMutability": "view",
        "type": "function"
    },
    {
        "inputs": [{
            "internalType": "bytes32",
            "name": "candidate",
            "type": "bytes32"
        }],
        "name": "validCandidate",
        "outputs": [{
            "internalType": "bool",
            "name": "",
            "type": "bool"
        }],
        "stateMutability": "view",
        "type": "function"
    },
    {
        "inputs": [{
            "internalType": "bytes32",
            "name": "candidate",
            "type": "bytes32"
        }],
        "name": "voteForCandidate",
        "outputs": [],
        "stateMutability": "nonpayable",
        "type": "function"
    },
    {
        "inputs": [{
            "internalType": "bytes32",
            "name": "",
            "type": "bytes32"
        }],
        "name": "votesReceived",
        "outputs": [{
            "internalType": "uint8",
            "name": "",
            "type": "uint8"
        }],
        "stateMutability": "view",
        "type": "function"
    }
]

var myContract = new web3.eth.Contract(abi)

// deplay 的 字节码
var data = "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"

var candidateNames = ['0x416c696365', '0x4265747479', '0x5365615361']
myContract.deploy({
    data: data,
    arguments: [candidateNames]
}).send({
    from: '0x88F3f579A8f1A84376884286Bd4A7927593834D7',
    gas: 1500000,
    gasPrice: '1000000'
}, function(error, result) {
    console.log(result)
})

[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-mOlQXBWo-1643027019299)(C:\Users\Lenovo\AppData\Local\Temp\1643014387962.png)]