利用github给国外文件下载加速

前言

作为一名程序员，经常需要下载一些编程相关的环境，而国内的网络环境大家都知道，有的文件用浏览器是下载不动的，于是我有了利用github下载文件的想法。

我的demo项目地址：https://github.com/bobowire/wireboy.remote.download （为保护github这片净土，已设置为私有）

参考资料：

NodeJS使用node-fetch下载文件并显示下载进度示例：https://www.jianshu.com/p/4b58711cb72a
nodejs——发送邮件（带附件）：https://www.cnblogs.com/yourstars/p/6728931.html

觉得好玩的，大家可以点个赞~

下载加速原理

使用github的Action远程执行文件下载（下载qt环境速度可以达到3mb/s），然后将下载的文件进行分片，每片15mb，分片后的文件以邮件附件的方式发送到国内邮箱，我们通过下载邮箱中的附件，将分片的附件合并成完整文件，从而实现不FQ、不用下载器也能下载国外文件的目的。

简单点说

github远程下载
文件分片
通过邮箱发到国内
对附件进行合并

使用方法

新建github项目
创建js文件download.js文件，内容请查阅后文
创建workflows/RunDownload.yml文件，内容请查阅后文
修改download.js中的fileURL 变量值，此为文件url地址
在项目github->settings->Secrets中，点击右上方“new responsitory secret”按钮，添加”EMAILPASS”,”SENDEMAIL”,”TOEMAIL”变量（授权码、发送邮箱、目标邮箱）
以上全部完成后，我们每次修改download.js文件的fileURL地址，github都会自动进行一次下载。原理请自行百度“github action”。

注意：

授权码（EMAILPASS）是指“邮箱第三方登录授权码”，如何获取授权码，以QQ邮箱为例，请点击：http://jingyan.baidu.com/article/fedf0737af2b4035ac8977ea.html

github Action文件（RunDownload.yml）

name: Github wireboy.remote.download
 
on:
    push:
        branches:
            - main
    schedule:
     - cron: \'* * * * *\'
jobs:
    build:
        runs-on: ubuntu-latest
 
        steps:
            - name: Checkout codes
              uses: actions/checkout@v2
            - name: Use Node.js
              uses: actions/setup-node@v1
              with:
                node-version: \'12.x\'
            - name: Run
              run: npm install
              
            - run: node download.js
              
              env:
                EMAILPASS: ${{ secrets.EMAILPASS }}
                SENDEMAIL: ${{ secrets.SENDEMAIL }}
                TOEMAIL: ${{ secrets.TOEMAIL }}

源代码（download.js）

const fetch = require("node-fetch");
const fs = require("fs");
const path = require("path");
const progressStream = require(\'progress-stream\');
const nodemailer = require(\'nodemailer\');


//下载 的文件 地址 （https://nodejs.org/dist/v12.18.3/node-v12.18.3-x64.msi）
//vscode地址：https://az764295.vo.msecnd.net/stable/ea3859d4ba2f3e577a159bc91e3074c5d85c0523/VSCodeUserSetup-x64-1.52.1.exe
let fileURL = \'https://az764295.vo.msecnd.net/stable/ea3859d4ba2f3e577a159bc91e3074c5d85c0523/VSCodeUserSetup-x64-1.52.1.exe\';

//分割后文件集合
let attachments = [];
//每个邮件附件最大数量
let perEmailAttachmentMaxCount = 1;
//每个附件最大大小
let attachmentMaxSize = 1024 * 1024 * 45;
//下载保存的文件路径
let fileSavePath = path.join(__dirname, path.basename(fileURL));
//缓存文件路径
let tmpFileSavePath = fileSavePath + ".tmp";
//创建写入流
const fileStream = fs.createWriteStream(tmpFileSavePath).on(\'error\', function (e) {
    console.error(\'error==>\', e)
}).on(\'ready\', function () {
    console.log("开始下载:", fileURL);
}).on(\'finish\', function () {
    //下载完成后重命名文件
    fs.renameSync(tmpFileSavePath, fileSavePath);
    console.log(\'文件下载完成:\', fileSavePath);
    const readstream = fs.createReadStream(fileSavePath);
	let i = 0;
	console.time(\'readtime\');
    let patchIndex = 0;


	readstream.on(\'readable\', () => {
        {
            let chunk = readstream.read(attachmentMaxSize);
            while (null !== chunk) {
                patchIndex = patchIndex + 1;
                // console.log(\'read times:\'+patchIndex)
                // console.log(fileSavePath+\'.email_\'+patchIndex);

                let emailFilePath = fileSavePath+\'.email_\'+patchIndex;
                let emailFile = fs.createWriteStream(emailFilePath);
                emailFile.write(chunk);
                emailFile.end();
                
                attachments.push({
                    filename: patchIndex+\'_\'+path.basename(fileURL),
                    path: emailFilePath,
                });

		        chunk = readstream.read(attachmentMaxSize);
            }
        }
	});
	readstream.on(\'close\', () => {
        console.timeEnd(\'readtime\');
        if(attachments.length > 1)
        {
            attachments.push({
                filename: \'文件分割合并器(SplitMergeFile).exe\',
                path: path.join(__dirname, \'SplitMergeFile.exe\')
            });
        }
        let sendIndex = 1;
        let sendFiles = [];
        let total = attachments.length / perEmailAttachmentMaxCount;
        var i = 0;
        for(i = 0; i < attachments.length; i++)
        {
            sendFiles.push(attachments[i]);
            if(sendFiles.length >= perEmailAttachmentMaxCount)
            {
                sendEmail(sendFiles,sendIndex,total);
                sendFiles = [];
                sendIndex += 1;
            }
        }
        if(sendFiles.length > 0)
        {
            sendEmail(sendFiles,sendIndex,total);
            sendFiles = [];
        }

    });
    
});

var sendEmail = function(sendFiles,patchIndex,total){
    let msg = createEmailMessage(path.basename(fileURL) + \'_Part\' + patchIndex + \'/\' + total, sendFiles);
    console.log(\'Send Mail Part_\' + patchIndex + \'/\' + total + \'   \' + path.basename(fileURL));
    var i;
    for(i = 0; i < msg.attachments.length; i++)
    {
        console.log(msg.attachments[i].path);
    }
    var transporter = createTransporter();
    transporter.sendMail(msg, (error, info) => {
        if (error) {
            console.log(\'Error occurred\');
            console.log(error.message);
            return;
        }
        console.log(path.basename(fileURL) + \'_Part\' + patchIndex + \' sent successfully! \');
        // console.log(\'Server responded with "%s"\', info.response);
        transporter.close();
    });
};

//请求文件
fetch(fileURL, {
    method: \'GET\',
    headers: { \'Content-Type\': \'application/octet-stream\' },
    // timeout: 100,    
}).then(res => {
    //获取请求头中的文件大小数据
    let fsize = res.headers.get("content-length");
    //创建进度
    let str = progressStream({
        length: fsize,
        time: 100 /* ms */
    });
    // 下载进度 
    str.on(\'progress\', function (progressData) {
        //不换行输出
        let percentage = Math.round(progressData.percentage) + \'%\';
        console.log(percentage);
        // process.stdout.write(\'\033[2J\'+);
        // console.log(progress);
        /*
        {
            percentage: 9.05,
            transferred: 949624,
            length: 10485760,
            remaining: 9536136,
            eta: 42,
            runtime: 3,
            delta: 295396,
            speed: 949624
        }
        */
    });
    res.body.pipe(str).pipe(fileStream);
}).catch(e => {
    //自定义异常处理
    console.log(e);
});



var createTransporter = function(){
    return nodemailer.createTransport({
        service: \'smtp.163.com\',
        host: "smtp.163.com",
        secureConnection: true,
        port:465,
        auth: {
            user: process.env.SENDEMAIL,//发送者邮箱
            pass: process.env.EMAILPASS //邮箱第三方登录授权码
        },
        debug: true
    },{
        from: process.env.SENDEMAIL,//发送者邮箱
        headers: {
            \'X-Laziness-level\': 1000
        }
    });
} 

console.log(\'SMTP Configured\');

var createEmailMessage = function(subject,sendFiles){
    var message = {
        // Comma separated lsit of recipients 收件人用逗号间隔
        to: process.env.TOEMAIL,
    
        // Subject of the message 信息主题
        subject:  subject,
    
        // plaintext body
        // text: \'请查阅附件\',
    
        // Html body
        html: \'<p>下载文件成功!</p><p>下载地址：\' + fileURL + \'</p><p>感谢github提供的下载渠道，详见博客《利用github给国外文件下载加速》 - https://www.cnblogs.com/zhuxiaoxiao/p/14280136.html</p>\',
    
        // Apple Watch specific HTML body 苹果手表指定HTML格式
        // watchHtml: \'<b>Hello</b> to myself\',
    
        // An array of attachments 附件
        attachments: sendFiles
        // [
            // String attachment
           //  {
           //      filename: \'notes.txt\',
           //      content: \'Some notes about this e-mail\',
           //      contentType: \'text/plain\' // optional,would be detected from the filename 可选的，会检测文件名
           //  },
           //  // Binary Buffer attchment
           //  {
           //      filename: \'image.png\',
           //      content: Buffer.from(\'iVBORw0KGgoAAAANSUhEUgAAABAAAAAQAQMAAAAlPW0iAAAABlBMVEUAAAD/\' +
           //         \'//+l2Z/dAAAAM0lEQVR4nGP4/5/h/1+G/58ZDrAz3D/McH8yw83NDDeNGe4U\' +
           //         \'g9C9zwz3gVLMDA/A6P9/AFGGFyjOXZtQAAAAAElFTkSuQmCC\', \'base64\'),
           //      cid: \'00001\'  // should be as unique as possible 尽可能唯一
           //  },
            // File Stream attachment
            // {
            //     filename: filename,
            //     path: filepath,
            //     // cid: \'00002\'  // should be as unique as possible 尽可能唯一
            //  }
        // ]
    
    };
    return message;
};