> For the complete documentation index, see [llms.txt](https://how2realize.gitbook.io/project/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://how2realize.gitbook.io/project/zen-yang-shi-xian-de/kai-fa-yi-tai-fang-dapp.md).
# 开发以太坊DAPP--水果机
## 原理
* 使用 truffle 框架，solidity语言进行智能合约的开发和部署
* 使用 web3.js 来进行页面与智能合约的交互
* 使用 ganache-cli 作为测试链进行测试
* 使用metamask作为钱包
## 机器环境
* Win10
* Node.js
## 编写智能合约
```javascript
npm isntall -g ganache-cli
npm install -g solc
npm install -g truffle
truffle init
npm install --save truffle-contract
npm install --save web3
cd a dir
touch ./contracts/SlotMachine.sol
```
{% code title="SlotMachine.sol" %}
```typescript
// 声明编译器版本号
pragma solidity ^0.4.4;
// 智能合约类
contract SlotMachine {
address public slotMachineFunds;
// 每个硬币的价格
uint256 public coinPrice = 0.1 ether;
// 合约所有者的地址
address owner;
// 游戏开始的事件
event Rolled(address sender, uint rand1, uint rand2, uint rand3);
// 存放地址到余额的映射
mapping (address => uint) pendingWithdrawals;
// 权限装饰器，只有合约所有者才有权限
modifier onlyOwner() {
require(owner == msg.sender);
_;
}
function SlotMachine() {
owner = msg.sender;
}
//游戏逻辑，payable表示每次游戏都要给coinPrice的钱
function oneRoll() payable {
require(msg.value >= coinPrice);
uint rand1 = randomGen(msg.value);
uint rand2 = randomGen(msg.value + 10);
uint rand3 = randomGen(msg.value + 20);
uint result = calculatePrize(rand1, rand2, rand3);
Rolled(msg.sender, rand1, rand2, rand3);
pendingWithdrawals[msg.sender] += result;
}
// 查看合约的余额
function contractBalance() constant returns(uint) {
return this.balance;
}
// 计算游戏结果
function calculatePrize(uint rand1, uint rand2, uint rand3) constant returns(uint) {
if(rand1 == 5 && rand2 == 5 && rand3 == 5) {
return coinPrice * 30;
} else if (rand1 == 6 && rand2 == 5 && rand3 == 6) {
return coinPrice * 20;
} else if (rand1 == 4 && rand2 == 4 && rand3 == 4) {
return coinPrice * 15;
} else if (rand1 == 3 && rand2 == 3 && rand3 == 3) {
return coinPrice * 12;
} else if (rand1 == 2 && rand2 == 2 && rand3 == 2) {
return coinPrice * 10;
} else if (rand1 == 1 && rand2 == 1 && rand3 == 1) {
return coinPrice * 5;
} else if ((rand1 == rand2) || (rand1 == rand3) || (rand2 == rand3)) {
return coinPrice;
} else {
return 0;
}
}
// 退票出钱
function withdraw() {
uint amount = pendingWithdrawals[msg.sender];
pendingWithdrawals[msg.sender] = 0;
msg.sender.transfer(amount);
}
// 查看用户余额
function balanceOf(address user) constant returns(uint) {
return pendingWithdrawals[user];
}
// 设置游戏硬币的价格
function setCoinPrice(uint _coinPrice) onlyOwner {
coinPrice = _coinPrice;
}
function() onlyOwner payable {
}
function cashout(uint _amount) onlyOwner {
msg.sender.transfer(_amount);
}
// 生成随机数
function randomGen(uint seed) private constant returns (uint randomNumber) {
return (uint(sha3(block.blockhash(block.number-1), seed )) % 6) + 1;
}
}
```
{% endcode %}
## 编写迁移脚本
{% code title="migrations/2\_deploy\_contracts.js" %}
```typescript
var SlotMachine = artifacts.require('./SlotMachine');
module.exports = (deployer) => {
deployer.deploy(SlotMachine);
}
```
{% endcode %}
## 配置truffle.js文件
{% code title="truffle.js" %}
```typescript
module.exports = {
networks: {
development: {
host: "localhost",
port: 8545,
network_id: "*"
}
}
};
```
{% endcode %}
## 启动ganache-cli测试链
* ganache-cli
* 记录账号信息
## 迁移部署合约
* `truffle migrate`
## 启动前端
* npm install && npm run dev
## GitHub地址
*
## 效果展示
