如何在流完成管道后呈现响应？

Question

这就是我想要的，服务器是一个文件服务器，当客户端请求某个文件时，它会将该文件流回。我尝试这样做而不是 koi-static，但是 dest.jpg 只包含 'Not found'.

客户代码：

var Koa = require('koa');
var Router = require('koa-router');
const HttpStatus = require('http-status');
const fs = require('fs');
const koaBody = require('koa-body');
const request = require('request');

const tempSaveFile = fs.createWriteStream('dest.jpg');

const writeStream = request.post('http://localhost:3456/getfile/src.jpg').pipe(tempSaveFile);
writeStream.on('finish', () => {
    tempSaveFile.end();
    console.log('Upload successful! ');
});

服务器代码：

var Koa = require('koa');
var Router = require('koa-router');
const HttpStatus = require('http-status');
const fs = require('fs');
const koaBody = require('koa-body');

var app = new Koa();
var router = new Router();
const serve = require('koa-static');

router
    .post([`/getfile/:fileName`],
        (ctx) => {
            const { params: { fileName } } = ctx;
            console.error(`------- server will return ${fileName} --------`);

            const readStream = fs.createReadStream(fileName).pipe(ctx.res);

            readStream.on('finish', () => {
                console.error('---- server finished stream ----');
                ctx.status = HttpStatus.OK;
            });
        })

app.use(router.routes());
app.use(router.allowedMethods());

app.listen(3456);

当我将服务器改成koa-static时，客户端可以成功获取文件，diff一下，看起来是一样的。

我怀疑服务器 returns 在完成之前速度太快，但另一个 post 说这是等待管道完成的方法。 callback to handle completion of pipe 有什么建议么？谢谢！

Answer 1

好的，我添加了异步，现在工作

const multiparty = require('multiparty');
const multer = require('koa-multer');
const request = require('request');

var app = new Koa();
var router = new Router();
const serve = require('koa-static');

const streamEnd = fd => new Promise((resolve, reject) => {
    fd.on('end', () => {console.error('-- 51 --'); resolve(51); });
    fd.on('finish', () => {console.error('-- 53 --'); resolve(53); });
    fd.on('error', reject);
});

router
    .get([`/getfile/:fileName`],
        async (ctx) => {
            const { params: { fileName } } = ctx;
            console.error(`------- server will return ${fileName} --------`);

            if (fs.existsSync(fileName)) {
                const readStream = fs.createReadStream(fileName).pipe(ctx.res);
                await streamEnd(readStream);

                ctx.status = HttpStatus.OK;
            } else {
                console.error(`File ${fileName} doesnot exist`);
                ctx.status = HttpStatus.INTERNAL_SERVER_ERROR;
            }
        })

app.use(serve('./customer'));
app.use(router.routes());
app.use(router.allowedMethods());

app.listen(3456);

如何在流完成管道后呈现响应？

How to render response after stream finished pipe?

node.js

koa