下载文件

 var res = await axios.get(url,{responseType : "stream"});

示例：

在koa2的get请求里从别处下载文件后直接转回给前端

const Koa = require('koa');
const Router = require('koa2-router')
const axios = require('axios')

const app = new Koa();
const router = new Router();
const port = 3000;

router.get('/download',async (ctx, next) => {
  const url = <url from other website>
  var res = await axios.get(url,{responseType : "stream"});
  ctx.set("Content-Type", res.headers['content-type']);
  ctx.response.body = res.data;
});


app.use(router);

app.listen(port,() => {
    console.log(`web app started, listening at ${port}`);
});

上传文件

?示例：从别的网络下载文件后，再上传到另外一个网站上

const axios = require('axios');
const FormData = require('form-data')


const upload = async () => {
    var url = <the url from other website>;
    var res = await axios.get(url,{responseType : "stream"});
   
    const formData = new FormData();
    formData.append("test",'test');
    formData.append("file",res.data,fileName);
    await  axios.post(<uploadUrl>, formData, {
            headers: formData.getHeaders(),
            maxBodyLength: Infinity 
     });
}

参考：? ??Send a File With Axios in Node.js - Maxim OrlovEverything you need to know about sending files with axios in Node.js — from creating a form to setting the right headers.https://maximorlov.com/send-a-file-with-axios-in-nodejs/