安装

npm i @koa/multer

注

安装 npm i @koa/multer 警告如下:

npm warn deprecated @babel/plugin-proposal-export-namespace-from@7.18.9:

This proposal has been merged to the ECMAScript standard and thus this plugin is no longer maintained.

Please use @babel/plugin-transform-export-namespace-from instead.

这个警告说明使用的插件(@babel/plugin-proposal-export-namespace-from)已过时,

该语法已合并到了 ES 标准中, 因此不再需要此插件进行转换

import Koa from 'koa'
import Router from '@koa/router'
import BodyParser from '@koa/bodyparser'
import Cors from '@koa/cors'
import Multer from '@koa/multer'
import path from 'path'

const hostname = "127.0.0.1"
const port = 8008

const app = new Koa()
const router = new Router() //实例化一个 Router 对象

app.use(BodyParser()) //使用 @koa/bodyparser 中间件来解析 post 请求
app.use(Cors()) //允许跨域请求

//配置磁盘存储引擎
const storage = Multer.diskStorage({
    destination: (request, file, callbackFunc) => { //指定文件保存路径
        callbackFunc(null, './upload')
    },
    filename: (request, file, callbackFunc) => { //设置文件名
        callbackFunc(null, Date.now() + path.extname(file.originalname)) 
    },
})

const multer = Multer({  //实例化一个 Multer 对象
    storage, //磁盘存储引擎
    limits: { //限制条件
        fileSize: 2 * 1024 * 1024, // 限制文件大小为2MB
    },
    fileFilter: (request, file, callbackFunc) => { //文件过滤器
        let allowedTypes = ['image/jpeg', 'image/jpg', 'image/png']
        if (allowedTypes.includes(file.mimetype)) {
            callbackFunc(null, true)
        } else {
            callbackFunc(new Error('不支持的文件类型'), false)
        }
    }
})

//上传 http://127.0.0.1:8008/upload
router.post('/upload', multer.single('file'), async ctx => {
    const file = ctx.request.file // 获取上传的文件信息
    if (file) {
        console.log(file)
        ctx.body = "文件上传成功"
    }
})

app.use(async (ctx, next) => { //错误处理中间件
    try {
        await next()
    } catch (err) {
        //console.log('err:', err)
        ctx.status = 500
        ctx.body = 'err: ' + err.message
    }
})

app.use(router.routes()) //路由处理中间件

app.listen(port, hostname, () => {
    console.log(`服务器已启动: http://${hostname}:${port}`)
})