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基于以太坊Ethereum & IPFS的去中心化Ebay区块链项目详情链接
- 【IPFS + 区块链 系列】 入门篇 - IPFS环境配置
- 【IPFS + 区块链 系列】 入门篇 - IPFS+IPNS+个人博客搭建
- 【IPFS + 区块链 系列】 入门篇 - IPFS + Ethereum (上篇)-js-ipfs-api - 数据上传到IPFS
- 【IPFS + 区块链 系列】 入门篇 - IPFS + Ethereum (中篇)-js-ipfs-api - 图片上传到IPFS以及下载
这篇文章通过truffle unbox react
创建项目,安装ipfs-api
,将图片存储到ipfs
,将图片hash
存储到Ethereum
区块链,取数据时先从区块链读取图片hash
,再通过hash
从ipfs
读取数据,解决了区块链大数据存储成本高昂的问题。
阅读本文需要将先学习上面的系列文章,由于本文前端使用了大量的React语法,所以建议学习一些React语法,还需要学习truffle framework。
其实这篇文章的内容就是上面几篇文章的综合结合体,所以在这里我将不再对代码做过多的概述。
import React, {Component} from 'react'
import SimpleStorageContract from '../build/contracts/SimpleStorage.json'
import getWeb3 from './utils/getWeb3'
import './css/oswald.css'
import './css/open-sans.css'
import './css/pure-min.css'
import './App.css'
const ipfsAPI = require('ipfs-api');
const ipfs = ipfsAPI({host: 'localhost', port: '5001', protocol: 'http'});
const contract = require('truffle-contract')
const simpleStorage = contract(SimpleStorageContract)
let account;
// Declaring this for later so we can chain functions on SimpleStorage.
let contractInstance;
let saveImageOnIpfs = (reader) => {
return new Promise(function(resolve, reject) {
const buffer = Buffer.from(reader.result);
ipfs.add(buffer).then((response) => {
console.log(response)
resolve(response[0].hash);
}).catch((err) => {
console.error(err)
reject(err);
})
})
}
class App extends Component {
constructor(props) {
super(props)
this.state = {
blockChainHash: null,
web3: null,
address: null,
imgHash: null,
isWriteSuccess: false
}
}
componentWillMount() {
ipfs.swarm.peers(function(err, res) {
if (err) {
console.error(err);
} else {
// var numPeers = res.Peers === null ? 0 : res.Peers.length;
// console.log("IPFS - connected to " + numPeers + " peers");
console.log(res);
}
});
getWeb3.then(results => {
this.setState({web3: results.web3})
// Instantiate contract once web3 provided.
this.instantiateContract()
}).catch(() => {
console.log('Error finding web3.')
})
}
instantiateContract = () => {
simpleStorage.setProvider(this.state.web3.currentProvider);
this.state.web3.eth.getAccounts((error, accounts) => {
account = accounts[0];
simpleStorage.at('0x66e9bbfe244799149a9c4eb708a34ea7c9ce67e2').then((contract) => {
console.log(contract.address);
contractInstance = contract;
this.setState({address: contractInstance.address});
return;
});
})
}
render() {
return (<div className="App">
{
this.state.address
? <h1>合约地址:{this.state.address}</h1>
: <div/>
}
<h2>上传图片到IPFS:</h2>
<div>
<label id="file">Choose file to upload</label>
<input type="file" ref="file" id="file" name="file" multiple="multiple"/>
</div>
<div>
<button onClick={() => {
var file = this.refs.file.files[0];
var reader = new FileReader();
// reader.readAsDataURL(file);
reader.readAsArrayBuffer(file)
reader.onloadend = function(e) {
console.log(reader);
saveImageOnIpfs(reader).then((hash) => {
console.log(hash);
this.setState({imgHash: hash})
});
}.bind(this);
}}>将图片上传到IPFS并返回图片HASH</button>
</div>
{
this.state.imgHash
? <div>
<h2>imgHash:{this.state.imgHash}</h2>
<button onClick={() => {
contractInstance.set(this.state.imgHash, {from: account}).then(() => {
console.log('图片的hash已经写入到区块链!');
this.setState({isWriteSuccess: true});
})
}}>将图片hash写到区块链:contractInstance.set(imgHash)</button>
</div>
: <div/>
}
{
this.state.isWriteSuccess
? <div>
<h1>图片的hash已经写入到区块链!</h1>
<button onClick={() => {
contractInstance.get({from: account}).then((data) => {
console.log(data);
this.setState({blockChainHash: data});
})
}}>从区块链读取图片hash:contractInstance.get()</button>
</div>
: <div/>
}
{
this.state.blockChainHash
? <div>
<h3>从区块链读取到的hash值:{this.state.blockChainHash}</h3>
</div>
: <div/>
}
{
this.state.blockChainHash
? <div>
<h2>浏览器访问:{"http:https://localhost:8080/ipfs/" + this.state.imgHash}</h2>
<img alt="" style={{
width: 1600
}} src={"http:https://localhost:8080/ipfs/" + this.state.imgHash}/>
</div>
: <img alt=""/>
}
</div>);
}
}
export default App
- 项目下载
$ git clone https://github.com/liyuechun/IPFS-Ethereum-Image.git
$ cd IPFS-Ethereum-Image
$ npm install
- 运行程序
$ ipfs daemon // 终端一
$ npm start // 终端二
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