Truffle 快速构建 DApp

2020-01-14 18:07:42 阅读：574 来源： 互联网

标签：function const web3 gas DApp 构建 truffle Truffle ETH

简单介绍

官网传送门 Truffle是针对基于以太坊的Solidity语言的一套开发框架。本身基于Javascript，使用以太坊虚拟机（EVM）的世界一流的开发环境，用于区块链的测试框架和资产管道，旨在简化开发人员的生活。

安装truffle

安装前提：

预装nodejs

1.全局安装

npm install -g truffle

建立软链接

ln -s   /opt/node-v10.16.0-linux-x64/bin/truffle   /usr/local/bin/truffle

2.单个项目安装

npm install truffle

3.查看版本号

truffle version

4.安装成功

构建应用

快速开始 https://www.trufflesuite.com/docs/truffle/quickstart

创建项目

mkdir  simple-dapp

初始化项目

truffle init

Note: You can use the truffle unbox <box-name> command to download any of the other Truffle Boxes.

Note: To create a bare Truffle project with no smart contracts included, use truffle init.

本次采用基于webpack的box来构建

truffle unbox webpack

项目目录结构：

app/:Diretory for app
contracts/: Directory for Solidity contracts
migrations/: Directory for scriptable deployment files
test/: Directory for test files for testing your application and contracts
truffle-config.js: Truffle configuration file

创建合约：位于contracts文件夹下

pragma solidity >=0.4.21 <0.7.0;
contract Voting {
    //候选人得票数目
    mapping (bytes32=>uint8) public votesReceived;
    //候选人
    bytes32[] public candidateList;
    //构造器
    constructor(bytes32[] memory candidateNames) public {
        candidateList = candidateNames;
    }
    //查询投票数目
    function totalVotesFor(bytes32 candidate) view public returns (uint8){
        //非空校验
        require(validCandidate(candidate));
        return votesReceived[candidate];
    }
    //投票
    function VotingTo(bytes32 candidate) public {
        //非空校验
        require(validCandidate(candidate));
        //add
        votesReceived[candidate]+=1;
    }
    //校验
    function validCandidate(bytes32 candidate) view public returns (bool){
        for(uint i = 0;i<candidateList.length;i++){
            if(candidateList[i]==candidate){
                return true;
            }
        }
        return false;
    }
}

View Code

创建迁移文件：位于migrations文件夹下

const voting = artifacts.require('../contracts/Voting.sol')
module.exports = function (deployer) {
    deployer.deploy(voting,['Mikey','Leo','Don'].map(x=>web3.utils.asciiToHex(x)),{gas:2900000});
}

3_deploy_voting.js

编译智能合约

truffle compile

生成json文件

启动truffle的开发者模式

truffle develop

部署智能合约

migrate

Starting migrations...
======================
> Network name:    'develop'
> Network id:      5777
> Block gas limit: 0x6691b7


1_initial_migration.js
======================

   Deploying 'Migrations'
   ----------------------
   > transaction hash:    0x5d23f5f2452d41a20ee56b238efb21c9c81cb04e0105c874e5a26528538476e5
   > Blocks: 0            Seconds: 0
   > contract address:    0xD97313Cb13D2d39Bd8CD2CB6f3606aaCB89fa1Ad
   > block number:        13
   > block timestamp:     1578995366
   > account:             0x9c29d178Ba516574E372e3cf5Eda833359F4114F
   > balance:             99.96269208
   > gas used:            263741
   > gas price:           20 gwei
   > value sent:          0 ETH
   > total cost:          0.00527482 ETH


   > Saving migration to chain.
   > Saving artifacts
   -------------------------------------
   > Total cost:          0.00527482 ETH


2_deploy_contracts.js
=====================

   Deploying 'ConvertLib'
   ----------------------
   > transaction hash:    0x71bc728418b983c24aa541ffebffc8b2eafa53f1f5754e8a800a8f5688947069
   > Blocks: 0            Seconds: 0
   > contract address:    0x7caC31cFfE12a8A4D7F7bD83a97e3AF0E99206CE
   > block number:        15
   > block timestamp:     1578995366
   > account:             0x9c29d178Ba516574E372e3cf5Eda833359F4114F
   > balance:             99.95973214
   > gas used:            105974
   > gas price:           20 gwei
   > value sent:          0 ETH
   > total cost:          0.00211948 ETH


   Linking
   -------
   * Contract: MetaCoin <--> Library: ConvertLib (at address: 0x7caC31cFfE12a8A4D7F7bD83a97e3AF0E99206CE)

   Deploying 'MetaCoin'
   --------------------
   > transaction hash:    0x36bef9d0355bfcf5fd0fad5fd69574b9be37117b92883f03d1e76877cc07e045
   > Blocks: 0            Seconds: 0
   > contract address:    0xaAd2C9659fec947A764b244E37A281d219fb0a21
   > block number:        16
   > block timestamp:     1578995366
   > account:             0x9c29d178Ba516574E372e3cf5Eda833359F4114F
   > balance:             99.9529182
   > gas used:            340697
   > gas price:           20 gwei
   > value sent:          0 ETH
   > total cost:          0.00681394 ETH


   > Saving migration to chain.
   > Saving artifacts
   -------------------------------------
   > Total cost:          0.00893342 ETH


3_initial_voting.js
===================

   Deploying 'Voting'
   ------------------
   > transaction hash:    0x0a5c69ce8595788ef70513f2533af7f7a2c230525d50d68abaf30e49fed2c2ff
   > Blocks: 0            Seconds: 0
   > contract address:    0xdafBED4742Ff4b2bC17f0908D2E97DfA644B5417
   > block number:        18
   > block timestamp:     1578995366
   > account:             0x9c29d178Ba516574E372e3cf5Eda833359F4114F
   > balance:             99.94517058
   > gas used:            360358
   > gas price:           20 gwei
   > value sent:          0 ETH
   > total cost:          0.00720716 ETH


   > Saving migration to chain.
   > Saving artifacts
   -------------------------------------
   > Total cost:          0.00720716 ETH


Summary
=======
> Total deployments:   4
> Final cost:          0.0214154 ETH


truffle(develop)>

输出结果

部署成功

构建DApp

import Web3 from "web3";
import metaCoinArtifact from "../../build/contracts/MetaCoin.json";

const App = {
  web3: null,
  account: null,
  meta: null,

  start: async function() {
    const { web3 } = this;

    try {
      // get contract instance
      const networkId = await web3.eth.net.getId();
      const deployedNetwork = metaCoinArtifact.networks[networkId];
      this.meta = new web3.eth.Contract(
        metaCoinArtifact.abi,
        deployedNetwork.address,
      );

      // get accounts
      const accounts = await web3.eth.getAccounts();
      this.account = accounts[0];

      this.refreshBalance();
    } catch (error) {
      console.error("Could not connect to contract or chain.");
    }
  },

  refreshBalance: async function() {
    const { getBalance } = this.meta.methods;
    const balance = await getBalance(this.account).call();

    const balanceElement = document.getElementsByClassName("balance")[0];
    balanceElement.innerHTML = balance;
  },

  sendCoin: async function() {
    const amount = parseInt(document.getElementById("amount").value);
    const receiver = document.getElementById("receiver").value;

    this.setStatus("Initiating transaction... (please wait)");

    const { sendCoin } = this.meta.methods;
    await sendCoin(receiver, amount).send({ from: this.account });

    this.setStatus("Transaction complete!");
    this.refreshBalance();
  },

  setStatus: function(message) {
    const status = document.getElementById("status");
    status.innerHTML = message;
  },
};

window.App = App;

window.addEventListener("load", function() {
  if (window.ethereum) {
    // use MetaMask's provider
    App.web3 = new Web3(window.ethereum);
    window.ethereum.enable(); // get permission to access accounts
  } else {
    console.warn(
      "No web3 detected. Falling back to http://127.0.0.1:8545. You should remove this fallback when you deploy live",
    );
    // fallback - use your fallback strategy (local node / hosted node + in-dapp id mgmt / fail)
    App.web3 = new Web3(
      new Web3.providers.HttpProvider("http://127.0.0.1:8545"),
    );
  }

  App.start();
});

index.js

ICode9