一.ERC20代幣合約與web3調用

• ERC20代幣合約在小白看來覺得很高大上，但其實就是一個代幣的定義標準，方便其他dapp統一調用各種代幣的方法。如圖：
  

二.ERC20合約標準

【官方鏈接】

contract ERC20 {//**********9個函數*******//1.代幣的名字，如："黑馬幣"function name() constant public returns (string name);//2.代幣的簡稱，例如：HMBfunction symbol() public constant returns (string symbol);//3.代幣的最小分割量 token使用的小數點后幾位。比如如果設置為3，就是支持0.001表示function decimals() public constant returns (uint8 decimals);//4.token的總量function totalSupply() public constant returns (uint totalSupply);//5.余額 返回某個地址(賬戶)的賬戶余額function balanceOf(address _owner) public constant returns (uint balance);/*6.轉賬 交易代幣 從消息發送者賬戶中往_to賬戶轉數量為_value的token，從代幣合約的調用者地址上轉移 _value的數量token到的地址 _to【注意：并且必須觸發Transfer事件】*/function transfer(address _to, uint _value) public returns (bool success);/*7.兩個地址轉賬從賬戶_from中往賬戶_to轉數量為_value的token，與approve方法配合使用從地址 _from發送數量為 _value的token到地址 _to【注意：并且必須觸發Transfer事件】transferFrom方法用于允許合約代理某人轉移token。條件是from賬戶必須經過了approve。*/function transferFrom(address _from, address _to, uint _value) public returns (bool success);//8.批準_spender能從合約調用賬戶中轉出數量為_value的tokenfunction approve(address _spender, uint _value) public returns (bool success);//9.獲取_spender可以從賬戶_owner中轉出token的剩余數量function allowance(address _owner, address _spender) public constant returns (uint remaining);//**********2個事件*******//1.發生轉賬時必須要觸發的事件,transfer 和 transferFrom 成功執行時必須觸發的事件event Transfer(address indexed _from, address indexed _to, uint _value);//2.當函數 approve(address _spender, uint256 _value)成功執行時必須觸發的事件event Approval(address indexed _owner, address indexed _spender, uint _value); }

三.ERC20代幣合約實現

// 此合約實現不記得是哪看到后復制保存的......和官網案例類似 pragma solidity ^0.4.25;interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) public; }contract TokenERC20 {string public name; // ERC20標準string public symbol; // ERC20標準uint8 public decimals = 2; // ERC20標準，decimals 可以有的小數點個數，最小的代幣單位。18 是建議的默認值uint256 public totalSupply; // ERC20標準 總供應量// 用mapping保存每個地址對應的余額 ERC20標準mapping (address => uint256) public balanceOf;// 存儲對賬號的控制 ERC20標準mapping (address => mapping (address => uint256)) public allowance;// 事件，用來通知客戶端交易發生 ERC20標準event Transfer(address indexed from, address indexed to, uint256 value);// 事件，用來通知客戶端代幣被消費 ERC20標準event Burn(address indexed from, uint256 value);/*** 初始化構造*/function TokenERC20(uint256 initialSupply, string tokenName, string tokenSymbol) public {totalSupply = initialSupply * 10 ** uint256(decimals); // 供應的份額，份額跟最小的代幣單位有關，份額 = 幣數 * 10 ** decimals。balanceOf[msg.sender] = totalSupply; // 創建者擁有所有的代幣name = tokenName; // 代幣名稱symbol = tokenSymbol; // 代幣符號}/*** 代幣交易轉移的內部實現*/function _transfer(address _from, address _to, uint _value) internal {// 確保目標地址不為0x0，因為0x0地址代表銷毀require(_to != 0x0);// 檢查發送者余額require(balanceOf[_from] >= _value);// 確保轉移為正數個require(balanceOf[_to] + _value > balanceOf[_to]);// 以下用來檢查交易，uint previousBalances = balanceOf[_from] + balanceOf[_to];// Subtract from the senderbalanceOf[_from] -= _value;// Add the same to the recipientbalanceOf[_to] += _value;Transfer(_from, _to, _value);// 用assert來檢查代碼邏輯。assert(balanceOf[_from] + balanceOf[_to] == previousBalances);}/*** 代幣交易轉移* 從自己（創建交易者）賬號發送`_value`個代幣到 `_to`賬號* ERC20標準* @param _to 接收者地址* @param _value 轉移數額*/function transfer(address _to, uint256 _value) public {_transfer(msg.sender, _to, _value);}/*** 賬號之間代幣交易轉移* ERC20標準* @param _from 發送者地址* @param _to 接收者地址* @param _value 轉移數額*/function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {require(_value <= allowance[_from][msg.sender]); // Check allowanceallowance[_from][msg.sender] -= _value;_transfer(_from, _to, _value);return true;}/*** 設置某個地址（合約）可以創建交易者名義花費的代幣數。** 允許發送者`_spender` 花費不多于 `_value` 個代幣* ERC20標準* @param _spender The address authorized to spend* @param _value the max amount they can spend*/function approve(address _spender, uint256 _value) publicreturns (bool success) {allowance[msg.sender][_spender] = _value;return true;}/*** 設置允許一個地址（合約）以我（創建交易者）的名義可最多花費的代幣數。*-非ERC20標準* @param _spender 被授權的地址（合約）* @param _value 最大可花費代幣數* @param _extraData 發送給合約的附加數據*/function approveAndCall(address _spender, uint256 _value, bytes _extraData)publicreturns (bool success) {tokenRecipient spender = tokenRecipient(_spender);if (approve(_spender, _value)) {// 通知合約spender.receiveApproval(msg.sender, _value, this, _extraData);return true;}}/*** 銷毀我（創建交易者）賬戶中指定個代幣*-非ERC20標準*/function burn(uint256 _value) public returns (bool success) {require(balanceOf[msg.sender] >= _value); // Check if the sender has enoughbalanceOf[msg.sender] -= _value; // Subtract from the sendertotalSupply -= _value; // Updates totalSupplyBurn(msg.sender, _value);return true;}/*** 銷毀用戶賬戶中指定個代幣*-非ERC20標準* 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 enoughrequire(_value <= allowance[_from][msg.sender]); // Check allowancebalanceOf[_from] -= _value; // Subtract from the targeted balanceallowance[_from][msg.sender] -= _value; // Subtract from the sender's allowancetotalSupply -= _value; // Update totalSupplyBurn(_from, _value);return true;} }

四.ERC20代幣合約編譯

const solc = require('solc'); const path = require('path'); const fs = require('fs');//1.1 合約代碼文件路徑 const sourceFilePath = path.resolve(__dirname,'./TokenERC20.sol'); //1.2 合約編譯后的文件路徑 const bytecodeFilePath = path.resolve(__dirname,'./TokenERC20.bytecode'); //2.讀取文件 const source = fs.readFileSync(sourceFilePath,'utf-8'); //3.編譯 const result = solc.compile(source,1); //console.log(result);console.log('1.編譯完成:'+sourceFilePath);fs.writeFileSync(bytecodeFilePath,JSON.stringify(result.contracts[':TokenERC20']),'utf-8'); console.log('2.字節文件寫入完成:'+bytecodeFilePath);//4.暴露給外部訪問 //module.exports=result.contracts[':TokenERC20'];

五.web3調用

//1.1 導入 編譯好的 合約的 字節代碼 和 abi const path = require('path'); const fs = require('fs'); //1.2 合約編譯后的文件路徑 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.導入 hd錢包provider const HDWalletProvider = require("truffle-hdwallet-provider"); //3.助記詞（相當于是我們的私鑰） const mnemonic = "jar ... cat beef"; // 12 word mnemonic //4.創建 provider，可以用來訪問 以太坊真實網絡節點 const provider = new HDWalletProvider(mnemonic, "https://rinkeby.infura.io/v3/3a60f2b160....",1);//最后的0 是獲取 助記詞 的第1個地址//5.創建web對象 const Web3 = require('web3'); const web3= new Web3(provider);async function main(){console.log('開始與以太網交互......');const usrAdr = await web3.eth.getAccounts();//0x6c57CD10B4384C605aC748937b6cC1dF6C8eddA9web3.eth.defaultAccount = usrAdr[0];console.log('當前調用者的地址:' + web3.eth.defaultAccount);//6.部署合約到 以太網節點//let contractObj =await deployContract();//7.調用合約//7.0 創建 遠程智能合約const contractObj = await new web3.eth.Contract(JSON.parse(interface),'0x46495b091cd3Fcb789cC336c3B5e9041E28555b0');console.log('獲取【合約】對象成功!');// // 7.1 獲取指定地址余額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 顯示合約賬戶余額// await showContracMoney(contractObj);// //查看調用者購買的號碼// await showInvokerLuckNum(contractObj);// 7.3 開獎+// await withdrawLottery(contractObj);// 7.4 顯示買家賬戶列表// await showUsrList(contractObj);// await showContracMoney(contractObj);// 7.5 重置數據//await resetContract(contractObj);//await showManageAddress(contractObj);//await killContract(contractObj);console.log('結束!');}//啟動 main();// 1.部署合約 async function deployContract() {console.log('開始部署合約......');let contractObj = await new web3.eth.Contract(JSON.parse(interface)).deploy({data: bytecode,//TokenERC20(uint256 initialSupply, string tokenName, string tokenSymbol)arguments: ['1000000000','夢想零錢','DreamCoin']}).send({from:web3.eth.defaultAccount,gas:'1000000'});console.log('部署成功，合約地址：【'+contractObj.options.address+'】');return contractObj; }// 2.查詢余額 async function getBalanceAt(contractObj,usrAdr) {let usrMoney = await contractObj.methods.balanceOf(usrAdr).call();console.log('地址【'+usrAdr+'】余額：'+usrMoney); }//3.將當前調用者的錢 轉 money 金額給 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+'】轉賬【'+money+'】完畢');console.log('轉賬完畢~記錄如下：')console.log(result); }//4.授權（當前調用者授權給 spenderAdr 操作數額為 money 的代幣） 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+'】授權【'+money+'】完畢!');//console.log(result); }//5.查詢授權 async function allowanceAt(contractObj,ownerAdr,spenderAdr) {let result = await contractObj.methods.allowance(ownerAdr,spenderAdr).call();console.log('查詢：【'+ownerAdr+'】給【'+spenderAdr+'】剩余授權余額為：'+result); }//6.轉賬（匯款人地址，收款人地址，金額） 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+'】轉賬【'+money+'】完畢');//console.log(result); }

轉載于:https://www.cnblogs.com/jameszou/p/10131443.html

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