Node.js 管道超级代理响应到快速响应
我正试图用express应用程序“代理”某个文件。为什么下面的代码不起作用Node.js 管道超级代理响应到快速响应,node.js,express,superagent,Node.js,Express,Superagent,我正试图用express应用程序“代理”某个文件。为什么下面的代码不起作用 var app = require('express')() var request = require('superagent') app.get('/image', function(req, res, next) { request('http://s3.amazonaws.com/thumbnails.illustrationsource.com/huge.104.520060.JPG') .then
var app = require('express')()
var request = require('superagent')
app.get('/image', function(req, res, next) {
request('http://s3.amazonaws.com/thumbnails.illustrationsource.com/huge.104.520060.JPG')
.then(function(_res) {
_res.pipe(res)
})
})
app.listen(3001, function() {
console.log('listen')
})
当我直接“wget”一个文件时,它可以工作:
$ wget http://s3.amazonaws.com/thumbnails.illustrationsource.com/huge.104.520060.JPG
--2016-07-20 11:44:33-- http://s3.amazonaws.com/thumbnails.illustrationsource.com/huge.104.520060.JPG
Resolving s3.amazonaws.com... 54.231.120.106
Connecting to s3.amazonaws.com|54.231.120.106|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 21026 (21K) [image/jpeg]
Saving to: 'huge.104.520060.JPG'
huge.104.520060.JPG 100%[==============================================================================================>] 20.53K --.-KB/s in 0.1s
2016-07-20 11:44:34 (203 KB/s) - 'huge.104.520060.JPG' saved [21026/21026]
当我调用enpdpoint时,它永远不会结束:
$ wget localhost:3001/image
--2016-07-20 11:45:00-- http://localhost:3001/image
Resolving localhost... 127.0.0.1, ::1
Connecting to localhost|127.0.0.1|:3001... connected.
HTTP request sent, awaiting response...
一些细节:
$ npm -v
3.9.5
$ npm list --depth=0
express-superagent-pipe-file
├── express@4.14.0
└── superagent@2.1.0
superagent的响应对象不应被视为流,因为它可能已经是自动序列化的结果(例如,从JSON到JavaScript对象)。不使用响应对象,而是声明您可以直接将superagent请求通过管道传输到流:
var app = require('express')()
var request = require('superagent')
app.get('/image', function(req, res, next) {
request('http://s3.amazonaws.com/thumbnails.illustrationsource.com/huge.104.520060.JPG')
.pipe(res)
})
app.listen(3001, function() {
console.log('listen')
})
有了承诺,可以通过以下方式下载:
const fs = require('fs');
const path = require('path');
const download = (url) => {
return superagent.get(url)
.then((response) => {
const stream = fs.createWriteStream('file.ext');
return response.pipe(stream);
});
};
谢谢它起作用了。但是
\u res.pipe
函数在这种情况下做什么呢?@kharandziuk它似乎依赖于实现。根据,Node.js中的Response
对象实际上是ReadableStream
,但它是一个私有API,不应该在外部使用。文档中没有任何内容表明响应对象可以用作可读流。如果您仍然想知道\u res.pipe
之后会发生什么,下面是一个很好的注释: