koa --- 使用koa-multer上传文件+elementUI

核心代码

const upload = require('koa-multer') ({dest: './public/images'});
router.post('/upload', upload.single('file'), ctx=>{console.log('file', ctx.req.file);console.log('body', ctx.req.body);ctx.body = '上传成功';
})

目录结构如下

在这里插入图片描述

基本思路

1.通过浏览器访问url: http://localhost:3000/upload
2.服务器(koa)监听到对应的路由,调用路由处理函数
3.使用nunjucks模板引擎进行渲染,并返回给浏览器
4.浏览器渲染完毕后显示出来.
5.点击上传文件->上传
6.服务端监听到上传的POST请求,进行相应的处理并将处理结果返回给前端

总体代码

/upload.js

const koa = require('koa');
const app = new koa();
const router = new require('koa-router')();
const multer = require('koa-multer');
const nunjucks = require('koa-nunjucks-2');
const path = require('path');
const fs = require('fs');// nunjucks的配置
app.use(nunjucks({ext: 'html',path: __dirname,nunjucksConfig: {trimBlocks: true}
}));// upload的配置
const upload = multer({dest: 'uploads/'
});const types = upload.single('avatar');
router.get('/upload', async (ctx, next) => {await ctx.render('upload')
})router.post('/profile', types, async  (ctx, next) => {const { originalname, path: out_path, mimetype} = ctx.req.file;let newName = out_path + path.parse(originalname).ext;let err = fs.renameSync(out_path, newName);let result;if(err){result = JSON.stringify(err);} else {result = `<h1>upload success</h1>`;}ctx.body = result;
});app.use(router.routes());app.listen(3000, async () => {console.log('Server is running at http://localhost:3000');
})

/upload.html

<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><title>Document</title>
</head><body><form method="post" action="/profile" enctype="multipart/form-data">选择图片: <input name="avatar" id="upfile" type="file" /><input type="submit" value="提交" /></form>
</body></html>

Element-ui组件(前端)文件上传

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta http-equiv="X-UA-Compatible" content="ie=edge"><script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script><script src="https://unpkg.com/element-ui/lib/index.js"></script><link rel="stylesheet" href="https://unpkg.com/element-ui/lib/theme-chalk/index.css"><style>.avatar-uploader .el-upload{border: 1px dashed #d9d9d9;border-radius: 6px;cursor: pointer;position: relative;}.avatar-uploader-icon{font-size: 28px;color: #8c939d;width: 178px;height: 178px;line-height: 178px;text-align: center;}.avatar{width: 178px;height: 178px;display: block;}</style><title>文件上传</title>
</head>
<body><div id="app"><!-- ajax方式上传--><el-uploadclass="avatar-uploader"action="http://localhost:3000/users/upload":show-file-list="false":on-success="handleAvatarSuccess":before-upload="beforeAvatarUpload"><img v-if="imageUrl" :src="imageUrl" class="avatar" /><i v-else class="el-icon-plus avatar-uploader-icon"></i></el-upload></div><script>var app = new Vue({el:"#app",data(){return {imageUrl:""};},methods: {handleAvatarSuccess(res, file){this.$message.success("上传头像成功");this.imageUrl = URL.createObjectURL(file.raw);},beforeAvatarUpload(file) {const isJPG = file.type === 'image/jpeg';const isLt2M = file.size / 1024 / 1024 < 2;if(!isJPG){this.$message.error("上传头像图片只能是 JPG 格式!");}if(!isLt2M){this.$message.error("上传头像图片大小不能超过 2MB!");}return isJPG && isLt2M;}},})</script>
</body>
</html>