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
编写自己的解决方案，因为现有的不符合我的要求。
包括:
HTTPS下载(http下载时切换包到http) 基于承诺的函数 处理转发路径(状态302) 浏览器头-需要在一些cdn 来自URL的文件名(以及硬编码) 错误处理
打印出来的，更安全。如果你使用的是纯JS(没有Flow，没有TS)，可以随意删除类型，或者转换为.d。ts文件
index.js
import httpsDownload from httpsDownload;
httpsDownload('https://example.com/file.zip', './');
httpsDownload.[js|ts]
import https from "https";
import fs from "fs";
import path from "path";
function download(
url: string,
folder?: string,
filename?: string
): Promise<void> {
return new Promise((resolve, reject) => {
const req = https
.request(url, { headers: { "User-Agent": "javascript" } }, (response) => {
if (response.statusCode === 302 && response.headers.location != null) {
download(
buildNextUrl(url, response.headers.location),
folder,
filename
)
.then(resolve)
.catch(reject);
return;
}
const file = fs.createWriteStream(
buildDestinationPath(url, folder, filename)
);
response.pipe(file);
file.on("finish", () => {
file.close();
resolve();
});
})
.on("error", reject);
req.end();
});
}
function buildNextUrl(current: string, next: string) {
const isNextUrlAbsolute = RegExp("^(?:[a-z]+:)?//").test(next);
if (isNextUrlAbsolute) {
return next;
} else {
const currentURL = new URL(current);
const fullHost = `${currentURL.protocol}//${currentURL.hostname}${
currentURL.port ? ":" + currentURL.port : ""
}`;
return `${fullHost}${next}`;
}
}
function buildDestinationPath(url: string, folder?: string, filename?: string) {
return path.join(folder ?? "./", filename ?? generateFilenameFromPath(url));
}
function generateFilenameFromPath(url: string): string {
const urlParts = url.split("/");
return urlParts[urlParts.length - 1] ?? "";
}
export default download;
其他回答
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。
Vince Yuan的代码很棒，但似乎有问题。
function download(url, dest, callback) {
var file = fs.createWriteStream(dest);
var request = http.get(url, function (response) {
response.pipe(file);
file.on('finish', function () {
file.close(callback); // close() is async, call callback after close completes.
});
file.on('error', function (err) {
fs.unlink(dest); // Delete the file async. (But we don't check the result)
if (callback)
callback(err.message);
});
});
}
编写自己的解决方案，因为现有的不符合我的要求。
包括:
HTTPS下载(http下载时切换包到http) 基于承诺的函数 处理转发路径(状态302) 浏览器头-需要在一些cdn 来自URL的文件名(以及硬编码) 错误处理
打印出来的，更安全。如果你使用的是纯JS(没有Flow，没有TS)，可以随意删除类型，或者转换为.d。ts文件
index.js
import httpsDownload from httpsDownload;
httpsDownload('https://example.com/file.zip', './');
httpsDownload.[js|ts]
import https from "https";
import fs from "fs";
import path from "path";
function download(
url: string,
folder?: string,
filename?: string
): Promise<void> {
return new Promise((resolve, reject) => {
const req = https
.request(url, { headers: { "User-Agent": "javascript" } }, (response) => {
if (response.statusCode === 302 && response.headers.location != null) {
download(
buildNextUrl(url, response.headers.location),
folder,
filename
)
.then(resolve)
.catch(reject);
return;
}
const file = fs.createWriteStream(
buildDestinationPath(url, folder, filename)
);
response.pipe(file);
file.on("finish", () => {
file.close();
resolve();
});
})
.on("error", reject);
req.end();
});
}
function buildNextUrl(current: string, next: string) {
const isNextUrlAbsolute = RegExp("^(?:[a-z]+:)?//").test(next);
if (isNextUrlAbsolute) {
return next;
} else {
const currentURL = new URL(current);
const fullHost = `${currentURL.protocol}//${currentURL.hostname}${
currentURL.port ? ":" + currentURL.port : ""
}`;
return `${fullHost}${next}`;
}
}
function buildDestinationPath(url: string, folder?: string, filename?: string) {
return path.join(folder ?? "./", filename ?? generateFilenameFromPath(url));
}
function generateFilenameFromPath(url: string): string {
const urlParts = url.split("/");
return urlParts[urlParts.length - 1] ?? "";
}
export default download;
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。
const download = (url, path) => new Promise((resolve, reject) => {
http.get(url, response => {
const statusCode = response.statusCode;
if (statusCode !== 200) {
return reject('Download error!');
}
const writeStream = fs.createWriteStream(path);
response.pipe(writeStream);
writeStream.on('error', () => reject('Error writing to file!'));
writeStream.on('finish', () => writeStream.close(resolve));
});}).catch(err => console.error(err));
