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
你好,我认为你可以使用child_process模块和curl命令。
const cp = require('child_process');
let download = async function(uri, filename){
let command = `curl -o ${filename} '${uri}'`;
let result = cp.execSync(command);
};
async function test() {
await download('http://zhangwenning.top/20181221001417.png', './20181221001417.png')
}
test()
另外,当你想下载较大、多个文件时,你可以使用集群模块来使用更多的cpu内核。
其他回答
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');
var requestModule=require("request");
requestModule(filePath).pipe(fs.createWriteStream('abc.zip'));
超时解决方案,防止内存泄漏:
下面的代码是基于Brandon Tilley的回答:
var http = require('http'),
fs = require('fs');
var request = http.get("http://example12345.com/yourfile.html", function(response) {
if (response.statusCode === 200) {
var file = fs.createWriteStream("copy.html");
response.pipe(file);
}
// Add timeout.
request.setTimeout(12000, function () {
request.abort();
});
});
当您得到一个错误时,不要创建文件,并倾向于使用超时在X秒后关闭您的请求。
对于那些寻找es6风格的基于承诺的方式的人来说,我猜它会是这样的:
var http = require('http');
var fs = require('fs');
function pDownload(url, dest){
var file = fs.createWriteStream(dest);
return new Promise((resolve, reject) => {
var responseSent = false; // flag to make sure that response is sent only once.
http.get(url, response => {
response.pipe(file);
file.on('finish', () =>{
file.close(() => {
if(responseSent) return;
responseSent = true;
resolve();
});
});
}).on('error', err => {
if(responseSent) return;
responseSent = true;
reject(err);
});
});
}
//example
pDownload(url, fileLocation)
.then( ()=> console.log('downloaded file no issues...'))
.catch( e => console.error('error while downloading', e));
下载.js(即/project/utils/ Download.js)
const fs = require('fs');
const request = require('request');
const download = (uri, filename, callback) => {
request.head(uri, (err, res, body) => {
console.log('content-type:', res.headers['content-type']);
console.log('content-length:', res.headers['content-length']);
request(uri).pipe(fs.createWriteStream(filename)).on('close', callback);
});
};
module.exports = { download };
app.js
...
// part of imports
const { download } = require('./utils/download');
...
// add this function wherever
download('https://imageurl.com', 'imagename.jpg', () => {
console.log('done')
});