以太坊ERC20代币合约案例

时间:2024-09-22 10:35:02

一.ERC20代币合约与web3调用

  • ERC20代币合约在小白看来觉得很高大上,但其实就是一个代币的定义标准,方便其他dapp统一调用各种代币的方法。如图:

    以太坊ERC20代币合约案例

二.ERC20合约标准

官方链接

contract ERC20 {
//**********9个函数*******
//1.代币的名字,如:"黑马币"
function name() constant public returns (string name);
//2.代币的简称,例如:HMB
function symbol() public constant returns (string symbol);
//3.代币的最小分割量 token使用的小数点后几位。比如如果设置为3,就是支持0.001表示
function decimals() public constant returns (uint8 decimals);
//4.token的总量
function totalSupply() public constant returns (uint totalSupply); //5.余额 返回某个地址(账户)的账户余额
function balanceOf(address _owner) public constant returns (uint balance); /*6.转账 交易代币 从消息发送者账户中往_to账户转数量为_value的token,
从代币合约的调用者地址上转移 _value的数量token到的地址 _to
【注意:并且必须触发Transfer事件】*/
function transfer(address _to, uint _value) public returns (bool success); /*7.两个地址转账
从账户_from中往账户_to转数量为_value的token,与approve方法配合使用
从地址 _from发送数量为 _value的token到地址 _to
【注意:并且必须触发Transfer事件】
transferFrom方法用于允许合约代理某人转移token。条件是from账户必须经过了approve。*/
function transferFrom(address _from, address _to, uint _value) public returns (bool success); //8.批准_spender能从合约调用账户中转出数量为_value的token
function approve(address _spender, uint _value) public returns (bool success);
//9.获取_spender可以从账户_owner中转出token的剩余数量
function allowance(address _owner, address _spender) public constant returns (uint remaining); //**********2个事件*******
//1.发生转账时必须要触发的事件,transfer 和 transferFrom 成功执行时必须触发的事件
event Transfer(address indexed _from, address indexed _to, uint _value);
//2.当函数 approve(address _spender, uint256 _value)成功执行时必须触发的事件
event Approval(address indexed _owner, address indexed _spender, uint _value);
}

三.ERC20代币合约实现

// 此合约实现不记得是哪看到后复制保存的......和官网案例类似
pragma solidity ^0.4.25; interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) public; } contract TokenERC20 {
string public name; // ERC20标准
string public symbol; // ERC20标准
uint8 public decimals = 2; // ERC20标准,decimals 可以有的小数点个数,最小的代币单位。18 是建议的默认值
uint256 public totalSupply; // ERC20标准 总供应量 // 用mapping保存每个地址对应的余额 ERC20标准
mapping (address => uint256) public balanceOf;
// 存储对账号的控制 ERC20标准
mapping (address => mapping (address => uint256)) public allowance; // 事件,用来通知客户端交易发生 ERC20标准
event Transfer(address indexed from, address indexed to, uint256 value); // 事件,用来通知客户端代币被消费 ERC20标准
event Burn(address indexed from, uint256 value); /**
* 初始化构造
*/
function TokenERC20(uint256 initialSupply, string tokenName, string tokenSymbol) public {
totalSupply = initialSupply * 10 ** uint256(decimals); // 供应的份额,份额跟最小的代币单位有关,份额 = 币数 * 10 ** decimals。
balanceOf[msg.sender] = totalSupply; // 创建者拥有所有的代币
name = tokenName; // 代币名称
symbol = tokenSymbol; // 代币符号
} /**
* 代币交易转移的内部实现
*/
function _transfer(address _from, address _to, uint _value) internal {
// 确保目标地址不为0x0,因为0x0地址代表销毁
require(_to != 0x0);
// 检查发送者余额
require(balanceOf[_from] >= _value);
// 确保转移为正数个
require(balanceOf[_to] + _value > balanceOf[_to]); // 以下用来检查交易,
uint previousBalances = balanceOf[_from] + balanceOf[_to];
// Subtract from the sender
balanceOf[_from] -= _value;
// Add the same to the recipient
balanceOf[_to] += _value;
Transfer(_from, _to, _value); // 用assert来检查代码逻辑。
assert(balanceOf[_from] + balanceOf[_to] == previousBalances);
} /**
* 代币交易转移
* 从自己(创建交易者)账号发送`_value`个代币到 `_to`账号
* ERC20标准
* @param _to 接收者地址
* @param _value 转移数额
*/
function transfer(address _to, uint256 _value) public {
_transfer(msg.sender, _to, _value);
} /**
* 账号之间代币交易转移
* ERC20标准
* @param _from 发送者地址
* @param _to 接收者地址
* @param _value 转移数额
*/
function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
require(_value <= allowance[_from][msg.sender]); // Check allowance
allowance[_from][msg.sender] -= _value;
_transfer(_from, _to, _value);
return true;
} /**
* 设置某个地址(合约)可以创建交易者名义花费的代币数。
*
* 允许发送者`_spender` 花费不多于 `_value` 个代币
* ERC20标准
* @param _spender The address authorized to spend
* @param _value the max amount they can spend
*/
function approve(address _spender, uint256 _value) public
returns (bool success) {
allowance[msg.sender][_spender] = _value;
return true;
} /**
* 设置允许一个地址(合约)以我(创建交易者)的名义可最多花费的代币数。
*-非ERC20标准
* @param _spender 被授权的地址(合约)
* @param _value 最大可花费代币数
* @param _extraData 发送给合约的附加数据
*/
function approveAndCall(address _spender, uint256 _value, bytes _extraData)
public
returns (bool success) {
tokenRecipient spender = tokenRecipient(_spender);
if (approve(_spender, _value)) {
// 通知合约
spender.receiveApproval(msg.sender, _value, this, _extraData);
return true;
}
} /**
* 销毁我(创建交易者)账户中指定个代币
*-非ERC20标准
*/
function burn(uint256 _value) public returns (bool success) {
require(balanceOf[msg.sender] >= _value); // Check if the sender has enough
balanceOf[msg.sender] -= _value; // Subtract from the sender
totalSupply -= _value; // Updates totalSupply
Burn(msg.sender, _value);
return true;
} /**
* 销毁用户账户中指定个代币
*-非ERC20标准
* Remove `_value` tokens from the system irreversibly on behalf of `_from`.
*
* @param _from the address of the sender
* @param _value the amount of money to burn
*/
function burnFrom(address _from, uint256 _value) public returns (bool success) {
require(balanceOf[_from] >= _value); // Check if the targeted balance is enough
require(_value <= allowance[_from][msg.sender]); // Check allowance
balanceOf[_from] -= _value; // Subtract from the targeted balance
allowance[_from][msg.sender] -= _value; // Subtract from the sender's allowance
totalSupply -= _value; // Update totalSupply
Burn(_from, _value);
return true;
}
}

四.ERC20代币合约编译

const solc = require('solc');
const path = require('path');
const fs = require('fs'); //1.1 合约代码文件路径
const sourceFilePath = path.resolve(__dirname,'./TokenERC20.sol');
//1.2 合约编译后的文件路径
const bytecodeFilePath = path.resolve(__dirname,'./TokenERC20.bytecode');
//2.读取文件
const source = fs.readFileSync(sourceFilePath,'utf-8');
//3.编译
const result = solc.compile(source,1);
//console.log(result); console.log('1.编译完成:'+sourceFilePath); fs.writeFileSync(bytecodeFilePath,JSON.stringify(result.contracts[':TokenERC20']),'utf-8');
console.log('2.字节文件写入完成:'+bytecodeFilePath); //4.暴露给外部访问
//module.exports=result.contracts[':TokenERC20'];

五.web3调用

//1.1 导入 编译好的 合约的 字节代码 和 abi
const path = require('path');
const fs = require('fs');
//1.2 合约编译后的文件路径
const bytecodeFilePath = path.resolve(__dirname,'./TokenERC20.bytecode');
const bytecodeJsonStr = fs.readFileSync(bytecodeFilePath,'utf-8');
const byteCodeJsonObj = JSON.parse(bytecodeJsonStr);
//const {bytecode,interface} = require('./compilCaiPiao');
const bytecode = byteCodeJsonObj.bytecode;
const interface = byteCodeJsonObj.interface; //2.导入 hd钱包provider
const HDWalletProvider = require("truffle-hdwallet-provider");
//3.助记词(相当于是我们的私钥)
const mnemonic = "jar ... cat beef"; // 12 word mnemonic
//4.创建 provider,可以用来访问 以太坊真实网络节点
const provider = new HDWalletProvider(mnemonic, "https://rinkeby.infura.io/v3/3a60f2b160....",1);//最后的0 是获取 助记词 的第1个地址 //5.创建web对象
const Web3 = require('web3');
const web3= new Web3(provider); async function main(){
console.log('开始与以太网交互......');
const usrAdr = await web3.eth.getAccounts();//0x6c57CD10B4384C605aC748937b6cC1dF6C8eddA9
web3.eth.defaultAccount = usrAdr[0];
console.log('当前调用者的地址:' + web3.eth.defaultAccount); //6.部署合约到 以太网节点
//let contractObj =await deployContract(); //7.调用合约
//7.0 创建 远程智能合约
const contractObj = await new web3.eth.Contract(JSON.parse(interface),'0x46495b091cd3Fcb789cC336c3B5e9041E28555b0');
console.log('获取【合约】对象成功!'); // // 7.1 获取指定地址余额
await getBalanceAt(contractObj,'0x85BCc0F34718e80c332d41C513B72f8640B05249');
//await transferTo(contractObj,'0x83E9e99B7f5018680930baE0C7801555C850D9C5',10000000);
//await approveTo(contractObj,'0x83E9e99B7f5018680930baE0C7801555C850D9C5',1000000000);
await allowanceAt(contractObj,'0x85BCc0F34718e80c332d41C513B72f8640B05249','0x83E9e99B7f5018680930baE0C7801555C850D9C5');
await transferFrom(contractObj,'0x85BCc0F34718e80c332d41C513B72f8640B05249','0x737Df786f6e86625258960970c6752Fd7926F752',1);
await allowanceAt(contractObj,'0x85BCc0F34718e80c332d41C513B72f8640B05249','0x83E9e99B7f5018680930baE0C7801555C850D9C5');
//await getBalanceAt(contractObj,'0x737Df786f6e86625258960970c6752Fd7926F752');
// //7.2 显示合约账户余额
// await showContracMoney(contractObj);
// //查看调用者购买的号码
// await showInvokerLuckNum(contractObj); // 7.3 开奖+
// await withdrawLottery(contractObj); // 7.4 显示买家账户列表
// await showUsrList(contractObj);
// await showContracMoney(contractObj);
// 7.5 重置数据
//await resetContract(contractObj);
//await showManageAddress(contractObj);
//await killContract(contractObj); console.log('结束!'); } //启动
main(); // 1.部署合约
async function deployContract() {
console.log('开始部署合约......');
let contractObj = await new web3.eth.Contract(JSON.parse(interface))
.deploy({
data: bytecode,//TokenERC20(uint256 initialSupply, string tokenName, string tokenSymbol)
arguments: ['1000000000','梦想零钱','DreamCoin']
}).send({
from:web3.eth.defaultAccount,
gas:'1000000'
}); console.log('部署成功,合约地址:【'+contractObj.options.address+'】');
return contractObj;
} // 2.查询余额
async function getBalanceAt(contractObj,usrAdr) {
let usrMoney = await contractObj.methods.balanceOf(usrAdr).call();
console.log('地址【'+usrAdr+'】余额:'+usrMoney);
} //3.将当前调用者的钱 转 money 金额给 usrAdrTo
async function transferTo(contractObj,usrAdrTo, money) {
let result = await contractObj.methods.transfer(usrAdrTo,money).send({
from:web3.eth.defaultAccount,
gas:'1000000'
});
console.log('【'+web3.eth.defaultAccount+'】向【'+usrAdrTo+'】转账【'+money+'】完毕');
console.log('转账完毕~记录如下:')
console.log(result);
} //4.授权(当前调用者授权给 spenderAdr 操作数额为 money 的代币)
async function approveTo(contractObj,spenderAdr, money){
let result = await contractObj.methods.approve(spenderAdr,money).send({
from:web3.eth.defaultAccount,
gas:'1000000'
});
console.log('【'+web3.eth.defaultAccount+'】向【'+spenderAdr+'】授权【'+money+'】完毕!');
//console.log(result);
} //5.查询授权
async function allowanceAt(contractObj,ownerAdr,spenderAdr) {
let result = await contractObj.methods.allowance(ownerAdr,spenderAdr).call();
console.log('查询:【'+ownerAdr+'】给【'+spenderAdr+'】剩余授权余额为:'+result);
} //6.转账(汇款人地址,收款人地址,金额)
async function transferFrom(contractObj,usrAdrFrom, usrAdrTo, money) {
let result = await contractObj.methods.transferFrom(usrAdrFrom,usrAdrTo,money).send({
from:web3.eth.defaultAccount,
gas:'1000000'
});
console.log('【'+usrAdrFrom+'】向【'+usrAdrTo+'】转账【'+money+'】完毕');
//console.log(result);
}