区块链探索|[Near Protocol] Near开发Demo浅析-Gamble Game Near（二）（Dapp）区块链|vue.js

[Near Protocol] Near开发Demo浅析-Gamble Game Near Dapp接着上一期继续分享
源代码在Github上可以找到，以下是Dapp链接：

https://github.com/Yang94J/Gamble_Game_Near_Front

简介
本项目依托Vue，搭建前端应用，调用near-api-js与部署好的合约进行交互，完成掷骰子功能。环境搭建

Prerequisite : 系统中应当已经安装好Nodejs，Vue3
项目搭建：

vue create gamble_gamble_near_front

最终代码框架如下：

区块链探索|[Near Protocol] Near开发Demo浅析-Gamble Game Near（二）（Dapp）

文章图片

主要对/components/GambleGame.vue、App.vue、config.js、main.js、store.js、.env、package.json及vue.config.js进行介绍。
代码解析
package.json
以下是package.json重点部分

"dependencies": { "@rollup/plugin-inject": "^4.0.4", "buffer": "^6.0.3", "core-js": "^3.8.3", "near-api-js": "^0.44.2", "vue": "^3.2.13", "vuex": "^4.0.2" },

此处指明了对buffer、near-api-js、vue、vuex等依赖（尤其是buffer，必须要引入并显式声明，否则工程会出现类似Can't find variable: Buffer之类的错误）
.env

VUE_APP_CONTRACT_NAME=gamble_game1.XXX.testnet

指明dapp所需调用的合约名称（测试网）
main.js

import { createApp } from 'vue' import App from './App.vue' import store from './store'import { Buffer } from "buffer"; global.Buffer = Buffer; createApp(App).use(store).mount('#app')

请注意此处显式声明了global.Buffer
config.js

const CONTRACT_NAME = process.env.VUE_APP_CONTRACT_NAME;

从.env文件中读取合约名称

case 'testnet': return { networkId: 'testnet', nodeUrl: 'https://rpc.testnet.near.org', contractName: CONTRACT_NAME, walletUrl: 'https://wallet.testnet.near.org', helperUrl: 'https://helper.testnet.near.org', explorerUrl: 'https://explorer.testnet.near.org', };

根据用户输入环境，选择对应的网络配置（此处为测试网）。
store.js
store.js存储数据到本地浏览器，获取缓存等，可以参考该链接

state: { contract: null, currentUser: null, wallet: null, nearConfig: null },

存储状态包括合约、当前用户、钱包和near配置

mutations: { setupNear(state, payload) { state.contract = payload.contract; state.currentUser = payload.currentUser; state.wallet = payload.wallet; state.nearConfig = payload.nearConfig; } }

设置state对象

async initNear({ commit }) { const nearConfig = getConfigurations('testnet'); const near = await nearApi.connect({ deps: { keyStore: new nearApi.keyStores.BrowserLocalStorageKeyStore() }, ...nearConfig }); const wallet = new nearApi.WalletConnection(near); console.log(wallet)let currentUser; if (wallet.getAccountId()) { currentUser = { accountId: wallet.getAccountId(), balance: (await wallet.account().state()).amount, balanceInNear : (await wallet.account().state()).amount / (10 ** 24), } }console.log(currentUser)const contract = await new nearApi.Contract(wallet.account(), process.env.VUE_APP_CONTRACT_NAME || 'gamble_game1.young_cn.testnet', { viewMethods: ['get_maximum_gamble_price'], changeMethods: ['gamble','sponsor'], sender: wallet.getAccountId() }); console.log(contract); // Commit and send to mutation. commit('setupNear', { contract, currentUser, wallet, nearConfig }); } }

此处initNear函数获取测试网配置，生成合约、钱包信息（需要用户登录）、用户信息等。
GambleGame.vue

Dice Gamble game

根据当前用户情况，生成登入登出按钮

Hi, {{currentUser.accountId}}, your balance is {{currentUser.balanceInNear}} Near

显示当前用户id，当前余额（CurrentUser信息参见store.js）

Maximum : {{gambleLimit}} Near

显示当前最大投注量，通过refresh函数访问智能合约刷新最大投注量

Gamble:

投注按钮，调用gamblegame方法进行投注

Sponsor:

赞助按钮，调用sponsorus方法进行赞助

async created(){ console.log("created") console.log(sessionStorage.getItem('gambleLimit')) if (sessionStorage.getItem('gambleLimit')) { this.gambleLimit = sessionStorage.getItem('gambleLimit') } },

用created钩子函数来自动获取最大投注量（否则数据将丢失）

async mounted() { var that= this console.log("Mount") setInterval( () => { console.log("refresh") that.refresh() },3000 ) },

使用mounted钩子函数来设置自动更新最大投注量-考虑合约的并发。

signIn() { this.wallet.requestSignIn( this.nearConfig.contractName, 'Near Gamble Game' ); }, signOut() { this.wallet.signOut(); window.location.replace(window.location.origin + window.location.pathname) },

signIn和signOut方法调用near.api.js实现与钱包的交互

async gamblegame(){ try{ await this.contract.gamble( {}, this.gas, Big(this.gamble).times(10**24).toFixed() ); }catch (e) { console.log(e); } }, async sponsorus(){ try{ await this.contract.sponsor( {}, this.gas, Big(this.sponsor).times(10**24).toFixed() ); }catch (e) { console.log(e); alert('Something went wrong! Check the console.'); } }, async refresh(){ this.gambleLimit = await this.contract.get_maximum_gamble_price() this.gambleLimit = this.gambleLimit / (10 ** 24) sessionStorage.setItem('gambleLimit',this.gambleLimit) } }

gambleGame、sponsorus和refresh都是异步方法。具体contract方法信息在store.js里通过以下进行声明：