使用truffle开发智能合约

使用truffle开发智能合约

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。

安装

npm install -g truffle

创建工程

truffle init会帮我们创建一个空工程。

D:\Android_Code\2018\blockchain
λ mkdir HelloDapp && cd HelloDapp

D:\Android_Code\2018\blockchain\HelloDapp
λ truffle.cmd init
Downloading...
Unpacking...
Setting up...
Unbox successful. Sweet!

Commands:

  Compile:        truffle compile
  Migrate:        truffle migrate
  Test contracts: truffle test

D:\Android_Code\2018\blockchain\HelloDapp
λ ls
contracts/  migrations/  test/  truffle-config.js  truffle.js

编写工程

这里推荐使用Goland或idea系列作为编辑器, 打开HelloDapp目录。然后下载Intellij-Solidity插件,就能支持Solidity语言。 具体操作步凑为: File->Settings->Plugins->Browse Respositories->Intellij-Solidity->Install。

1. 在contracts目录下新建Hello.sol文件。

pragma solidity ^0.4.23;

contract Hello {

	function print() public pure returns(string) {
		return "Hello World";
	}

	function add(uint n1, uint n2) public pure returns(uint) {
		return n1 + n2;
	}
}

2. 在test木下新建TestHello.sol文件。

pragma solidity ^0.4.23;

import "../contracts/Hello.sol";
import "truffle/Assert.sol";

contract TestHello {

	function testAdd() public {
		Hello hello = new Hello();
		uint result = hello.add(1, 20);
		Assert.equal(result, 21, "TestAdd");
	}

	function testPrint() public {
		Hello hello = new Hello();
	    string memory result = hello.print();
		Assert.equal(result, "Hello World", "TestPrint");
	}
}

注意方法名必须以test开头。否则单元测试不会执行该函数。

3. 在migrations目录下新建2_deploy_hello.js文件。

var Hello = artifacts.require("./Hello.sol");

module.exports = function(deployer) {
    deployer.deploy(Hello);
};

测试

在命令行执行truffle test

D:\Android_Code\2018\blockchain\HelloDapp
λ truffle.cmd test
Compiling .\contracts\Hello.sol...
Compiling .\contracts\Migrations.sol...
Compiling .\test\TestHello.sol...
Compiling truffle/Assert.sol...


  TestHello
    √ testAdd (80ms)
    √ testPrint (102ms)


  2 passing (1s)


D:\Android_Code\2018\blockchain\HelloDapp
λ truffle.cmd test
Compiling .\contracts\Hello.sol...
Compiling .\contracts\Migrations.sol...
Compiling .\test\TestHello.sol...
Compiling truffle/Assert.sol...


  TestHello
    √ testAdd (78ms)
    √ testPrint (101ms)


  2 passing (919ms)

如果只测试单个文件,也可以执行

truffle.cmd test ./test/TestHello.sol

编译

D:\Android_Code\2018\blockchain\HelloDapp
λ truffle.cmd compile
Compiling .\contracts\Hello.sol...
Compiling .\contracts\Migrations.sol...
Writing artifacts to .\build\contracts

会在工程的build目录下生成对应合约的.json文件,里面描述了合约的具体信息。如果有语法错误会输出错误提示。

部署合约

如果想部署合约,我们需要连接上一条区块链。Truffle内置了一条私链用于测试。它只能在本地电脑上使用,不能与以太坊主链交互。

我们可以使用 truffle.cmd develop命令创建私链,并与其交互。

D:\Android_Code\2018\blockchain\HelloDapp
λ truffle.cmd develop
Truffle Develop started at http://127.0.0.1:9545/

Accounts:
(0) 0x627306090abab3a6e1400e9345bc60c78a8bef57
(1) 0xf17f52151ebef6c7334fad080c5704d77216b732
(2) 0xc5fdf4076b8f3a5357c5e395ab970b5b54098fef
(3) 0x821aea9a577a9b44299b9c15c88cf3087f3b5544
(4) 0x0d1d4e623d10f9fba5db95830f7d3839406c6af2
(5) 0x2932b7a2355d6fecc4b5c0b6bd44cc31df247a2e
(6) 0x2191ef87e392377ec08e7c08eb105ef5448eced5
(7) 0x0f4f2ac550a1b4e2280d04c21cea7ebd822934b5
(8) 0x6330a553fc93768f612722bb8c2ec78ac90b3bbc
(9) 0x5aeda56215b167893e80b4fe645ba6d5bab767de

Private Keys:
(0) c87509a1c067bbde78beb793e6fa76530b6382a4c0241e5e4a9ec0a0f44dc0d3
(1) ae6ae8e5ccbfb04590405997ee2d52d2b330726137b875053c36d94e974d162f
(2) 0dbbe8e4ae425a6d2687f1a7e3ba17bc98c673636790f1b8ad91193c05875ef1
(3) c88b703fb08cbea894b6aeff5a544fb92e78a18e19814cd85da83b71f772aa6c
(4) 388c684f0ba1ef5017716adb5d21a053ea8e90277d0868337519f97bede61418
(5) 659cbb0e2411a44db63778987b1e22153c086a95eb6b18bdf89de078917abc63
(6) 82d052c865f5763aad42add438569276c00d3d88a2d062d36b2bae914d58b8c8
(7) aa3680d5d48a8283413f7a108367c7299ca73f553735860a87b08f39395618b7
(8) 0f62d96d6675f32685bbdb8ac13cda7c23436f63efbb9d07700d8669ff12b7c4
(9) 8d5366123cb560bb606379f90a0bfd4769eecc0557f1b362dcae9012b548b1e5

Mnemonic: candy maple cake sugar pudding cream honey rich smooth crumble sweet treat

⚠️  Important ⚠️  : This mnemonic was created for you by Truffle. It is not secure.
Ensure you do not use it on production blockchains, or else you risk losing funds.

truffle(develop)>

默认使用端口9545创建了一条测试链,并且为了方便测试,创建了10个账号。然后进入了truffle交互模式里。

接着使用migrate命令。部署合约到连上

truffle(develop)> migrate
Using network 'develop'.

Running migration: 1_initial_migration.js
  Deploying Migrations...
  ... 0x65c8b0cad9b8ea585a216fbf5e214386373e490ae7737176f01f7dcb7f8b4d00
  Migrations: 0x8cdaf0cd259887258bc13a92c0a6da92698644c0
Saving successful migration to network...
  ... 0xd7bc86d31bee32fa3988f1c1eabce403a1b5d570340a3a9cdba53a472ee8c956
Saving artifacts...
Running migration: 2_deploy_hello.js
  Deploying Hello...
  ... 0x4664bd718a7d9ef33ad9cbffcee02e38d80d0d4103e68b796e3e95c1f5bc0fc4
  Hello: 0x345ca3e014aaf5dca488057592ee47305d9b3e10
Saving successful migration to network...
  ... 0xf36163615f41ef7ed8f4a8f192149a0bf633fe1a2398ce001bf44c43dc7bdda0
Saving artifacts...
truffle(develop)>

这就成功部署到链上了,并且显示了交易id和合约地址。 其中0x345ca3e014aaf5dca488057592ee47305d9b3e10就是Hello合约的地址, 0x4664bd718a7d9ef33ad9cbffcee02e38d80d0d4103e68b796e3e95c1f5bc0fc4就是交易id。

与合约交互

truffle(develop)> Hello.address
'0x345ca3e014aaf5dca488057592ee47305d9b3e10'
truffle(develop)> Hello.deployed().then(inst => {HelloInst = inst});
undefined
truffle(develop)> HelloInst.print();
'Hello World'
truffle(develop)> Hello.deployed().then(function(inst) {HelloInst = inst;});
undefined
truffle(develop)> HelloInst.print();
'Hello World'
truffle(develop)> HelloInst.add(10, 200);
BigNumber { s: 1, e: 2, c: [ 210 ] }
truffle(develop)> HelloInst.add(1, 30).then(val => val.toNumber());
31
truffle(develop)> HelloInst.address
'0x345ca3e014aaf5dca488057592ee47305d9b3e10'

支持es6的箭头写法简化了不少。Hello.address和HelloInst.address都输了合约的地址

注意:

1.如果合约里写有构造函数

contract Hello {
    function Hello() public {
        
    }
}

如果是使用了新的版本编译器。可能会报错Warning: Defining constructors as functions with the same name as the contract is deprecated. Use "constructor(...) { ... }" instead. 最新版语言编译需要这么写:

contract Hello {
    constructors() public {
        
    }
}

2.修改了代码再执行migrate并不会生效,它只会部署没有部署过的合约。强制重新部署,可执行 migrate --reset。如果只想部署某一个合约,可执行migrate -f 2

3.执行truffle,不是truffle.cmd。会优先执行到当前工程目录下truffle.js配置文件。所以执行truffle.cmd可以避免这个问题。

4.truffle交互模式下,可少输入truffle。比如系统命令下执行truffle migrate,在truffle模式下只用输入migrate即可。连按2次ctrl+c或输入.exit可退出交互模式。

编辑于 2018-05-23