本文将会用typescript+react+react-dropzone+express.js实现前后端上传图片。当然是用typescript需要提前下载相应的模块，在这里就不依依介绍了。
第一步，配置tsconfig.js
"compilerOptions": { "outDir": "./public/", "sourceMap": true, "noImplicitAny": true, "module": "commonjs", "target": "es5", "jsx": "react" , "noImplicitAny": false, "suppressImplicitAnyIndexErrors": true }, "files": [ "./views/home/main.tsx" ], "exclude": [ "node_modules" ] }
2.配置webpack
var path = require('path'); var webpack = require('webpack'); var ExtractTextPlugin = require("extract-text-webpack-plugin"); var HtmlWebpackPlugin = require('html-webpack-plugin'); var title = { home: '首页', } module.exports = { entry: { home: [ 'babel-polyfill', './views/home/main.tsx' ], common: ['react','babel-polyfill'] }, output: { path: path.join(__dirname, 'views/wap'), filename: '[name].js', chunkFilename: '[id].build.js?[chunkhash]', publicPath: '/views/wap/', }, module: { loaders: [ { test: /\.tsx?$/, loader: 'ts-loader' }, { test: /\.(less|css)$/, loader: ExtractTextPlugin.extract('style', 'css!less'), }, { test:/\.(js|jsx)?$/, loader:'babel', exclude:/node_modules/, query:{compact:false,presets:['es2015','react','stage-0','stage-1','stage-2']} }, { test: /\.(png|jpg|gif)?$/, loaders: ['url?limit=8192&name=[name]_[sha512:hash:base64:7].[ext]'], }, { test: /\.(eot|woff|ttf|svg)$/, loader: 'file?limit=81920&name=[name]_[sha512:hash:base64:7].[ext]' }, ] }, resolve: { root: ['node_modules'], extensions: ['', '.js', '.jsx', '.html', '.json','.ts', '.tsx'], modulesDirectories: ['node_modules'], alias: {} }, externals: {}, plugins: [ new webpack.DefinePlugin({ 'process.env.NODE_ENV': '"production"' }), new webpack.HotModuleReplacementPlugin(), new ExtractTextPlugin('[name].[contenthash:20].css'), new webpack.optimize.UglifyJsPlugin({ compress: {warnings: false} }), new webpack.optimize.CommonsChunkPlugin('common', 'common.js'), new HtmlWebpackPlugin( { title: "", template: path.join(path.resolve(__dirname),'views/wap/myApp.html'), //模板文件 inject:'body', hash:true, //为静态资源生成hash值 minify:{ //压缩HTML文件 removeComments:false, //移除HTML中的注释 collapseWhitespace:false //删除空白符与换行符 } } ) ] };
3.react-dropzone
import * as Dropzone from 'react-dropzone'; <Dropzone accept="image/jpeg, image/png" onDrop={(accepted, rejected) => { this.setState({ accepted, rejected });this.drop(accepted[0].preview) }} style={{width:"100%",height:"120px",background:"#f2f2f2","padding-top":'90px',"cursor":"pointer","box-sizing":"content-box"}} > </Dropzone>
accept:表示图片的接受类型
onDrop代表图片加载以后触发
accepted:表示加载图片成功后相关信息，打印出来如下:
rejected：表示加载图片失败后，相关信息：
4.图片处理、上传
新建一个drop方法在触发onDrop后。
drop(src : any) : any{ const that = this; let img = src; let image = new Image(); image.crossOrigin = 'Anonymous'; image.src = img; image.onload = function(){ let base64 = that.getBase64Image(image); that.upLoadImg({imgData:base64}) } }
在这里我们使用base64传递，所以我们需要把图片转成base64，定义getBase64Image处理
getBase64Image(img :any) : string { let canvas = document.createElement("canvas"); canvas.width = img.width; canvas.height = img.height; let ctx = canvas.getContext("2d"); ctx.drawImage(img, 0, 0, img.width, img.height); let ext = img.src.substring(img.src.lastIndexOf(".")+1).toLowerCase(); let dataURL = canvas.toDataURL("image/"+ext); return dataURL; }
最终返回的是处理后图片的地址，然后上传
async upLoadImg(params : object) : Promise<any>{ let res = await axios.post('http://localhost:3000/upLoadImg',params); }
5.node部分
router/index.js
var express = require('express'); var router = express.Router(); var rf = require('fs'); var SetImg = require('./controller/uploadImg'); var setImg = new SetImg; router.post('/upLoadImg',setImg.setUploadImg); module.exports = router;
./controller/uploadImg.js
var rf = require('fs'); class SetImg { setUploadImg(req, res, next) { let imgData = req.body.imgData; let base64Data = imgData.replace(/^data:image\/\w+;base64,/, ""); let dataBuffer = new Buffer(base64Data, 'base64'); let timer = Number( new Date() ); rf.writeFile("views/images/artCover"+timer+".png",dataBuffer, function(err) { if(err) { res.json({"code":400,"verson":false,"msg":err}); }else { res.json({"code":100,"verson":true,"url":"views/src/common/images/artCover/"+timer+".png"}); } }); } } module.exports = SetImg;
拿到图片后先进行格式转换，然后将图片写入到本地，返回图片路径。