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以太坊ERC20代币合约案例

以太坊ERC20代币合约案例

作者: 前端老邹_伯通 | 来源:发表于2018-11-12 22:26 被阅读46次

    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:


      ERC20标准的用途

    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);
    }
    

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          本文标题:以太坊ERC20代币合约案例

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