如何在不使用第三方库的情况下使用Node.js下载文件?
我不需要什么特别的东西。我只想从给定的URL下载文件,然后将其保存到给定的目录。
如何在不使用第三方库的情况下使用Node.js下载文件?
我不需要什么特别的东西。我只想从给定的URL下载文件,然后将其保存到给定的目录。
当前回答
如果您正在使用express,请使用res.download()方法。否则使用fs模块。
app.get('/read-android', function(req, res) {
var file = "/home/sony/Documents/docs/Android.apk";
res.download(file)
});
(or)
function readApp(req,res) {
var file = req.fileName,
filePath = "/home/sony/Documents/docs/";
fs.exists(filePath, function(exists){
if (exists) {
res.writeHead(200, {
"Content-Type": "application/octet-stream",
"Content-Disposition" : "attachment; filename=" + file});
fs.createReadStream(filePath + file).pipe(res);
} else {
res.writeHead(400, {"Content-Type": "text/plain"});
res.end("ERROR File does NOT Exists.ipa");
}
});
}
其他回答
现代版本(ES6, Promise, Node 12。X +)适用于https/http。它还支持重定向302和301。我决定不使用第三方库,因为它可以很容易地使用标准Node.js库。
// download.js
import fs from 'fs'
import https from 'https'
import http from 'http'
import { basename } from 'path'
import { URL } from 'url'
const TIMEOUT = 10000
function download (url, dest) {
const uri = new URL(url)
if (!dest) {
dest = basename(uri.pathname)
}
const pkg = url.toLowerCase().startsWith('https:') ? https : http
return new Promise((resolve, reject) => {
const request = pkg.get(uri.href).on('response', (res) => {
if (res.statusCode === 200) {
const file = fs.createWriteStream(dest, { flags: 'wx' })
res
.on('end', () => {
file.end()
// console.log(`${uri.pathname} downloaded to: ${path}`)
resolve()
})
.on('error', (err) => {
file.destroy()
fs.unlink(dest, () => reject(err))
}).pipe(file)
} else if (res.statusCode === 302 || res.statusCode === 301) {
// Recursively follow redirects, only a 200 will resolve.
download(res.headers.location, dest).then(() => resolve())
} else {
reject(new Error(`Download request failed, response status: ${res.statusCode} ${res.statusMessage}`))
}
})
request.setTimeout(TIMEOUT, function () {
request.abort()
reject(new Error(`Request timeout after ${TIMEOUT / 1000.0}s`))
})
})
}
export default download
感谢安德烈·特卡琴科,我修改了他的要点
将其包含在另一个文件中并使用
const download = require('./download.js')
const url = 'https://raw.githubusercontent.com/replace-this-with-your-remote-file'
console.log('Downloading ' + url)
async function run() {
console.log('Downloading file')
try {
await download(url, 'server')
console.log('Download done')
} catch (e) {
console.log('Download failed')
console.log(e.message)
}
}
run()
这里还有另一种方法来处理它没有第三方依赖,也搜索重定向:
var download = function(url, dest, cb) {
var file = fs.createWriteStream(dest);
https.get(url, function(response) {
if ([301,302].indexOf(response.statusCode) !== -1) {
body = [];
download(response.headers.location, dest, cb);
}
response.pipe(file);
file.on('finish', function() {
file.close(cb); // close() is async, call cb after close completes.
});
});
}
说到处理错误,监听请求错误甚至更好。我甚至会通过检查响应代码来验证。这里认为只有200个响应代码成功,但其他代码可能很好。
const fs = require('fs');
const http = require('http');
const download = (url, dest, cb) => {
const file = fs.createWriteStream(dest);
const request = http.get(url, (response) => {
// check if response is success
if (response.statusCode !== 200) {
return cb('Response status was ' + response.statusCode);
}
response.pipe(file);
});
// close() is async, call cb after close completes
file.on('finish', () => file.close(cb));
// check for request error too
request.on('error', (err) => {
fs.unlink(dest, () => cb(err.message)); // delete the (partial) file and then return the error
});
file.on('error', (err) => { // Handle errors
fs.unlink(dest, () => cb(err.message)); // delete the (partial) file and then return the error
});
};
尽管这段代码相对简单,但我建议使用request模块,因为它处理更多http不支持的协议(你好,HTTPS!)。
可以这样做:
const fs = require('fs');
const request = require('request');
const download = (url, dest, cb) => {
const file = fs.createWriteStream(dest);
const sendReq = request.get(url);
// verify response code
sendReq.on('response', (response) => {
if (response.statusCode !== 200) {
return cb('Response status was ' + response.statusCode);
}
sendReq.pipe(file);
});
// close() is async, call cb after close completes
file.on('finish', () => file.close(cb));
// check for request errors
sendReq.on('error', (err) => {
fs.unlink(dest, () => cb(err.message)); // delete the (partial) file and then return the error
});
file.on('error', (err) => { // Handle errors
fs.unlink(dest, () => cb(err.message)); // delete the (partial) file and then return the error
});
};
编辑:
要使它与https兼容,请更改
const http = require('http');
to
const http = require('https');
我更喜欢request(),因为你可以同时使用http和https。
request('http://i3.ytimg.com/vi/J---aiyznGQ/mqdefault.jpg')
.pipe(fs.createWriteStream('cat.jpg'))
不要忘记处理错误!下面的代码是基于Augusto Roman的回答。
var http = require('http');
var fs = require('fs');
var download = function(url, dest, cb) {
var file = fs.createWriteStream(dest);
var request = http.get(url, function(response) {
response.pipe(file);
file.on('finish', function() {
file.close(cb); // close() is async, call cb after close completes.
});
}).on('error', function(err) { // Handle errors
fs.unlink(dest); // Delete the file async. (But we don't check the result)
if (cb) cb(err.message);
});
};