在NodeJS中下载大文件的方法是什么？

Question

以下服务器代码对于5GB文件使用 wget http://localhost:11146/base/bigFile.zip正常工作，但未使用客户端代码。

服务器端代码。

var http = require("http"); 
var fs = require("fs"); 
var filename = "base/bigFile.zip"; 

var serv = http.createServer(function (req, res) { 
    var stat = fs.statSync(filename); 
    res.writeHeader(200, {"Content-Length": stat.size}); 
    var fReadStream = fs.createReadStream(filename); 
    fReadStream.on('data', function (chunk) { 
     if(!res.write(chunk)){ 
      fReadStream.pause(); 
     } 
    }); 
    fReadStream.on('end', function() { 
     res.end(); 
    }); 
    res.on("drain", function() { 
     fReadStream.resume(); 
    }); 
}); 

serv.listen(1114); 

使用请求模块

客户端代码。这段代码有什么问题？

var request = require('request') 
request('http:/localhost:11146/base/bigFile.zip', function (error, response, body) { 
    console.log('error:', error); // Print the error if one occurred 
    console.log('statusCode:', response && response.statusCode); // Print the response status code if a response was received 
    console.log('body:', body); // Print the HTML for the Google homepage. 
}); 

误差为上述客户端代码低于 -

error: Error: Invalid protocol 
    at Request.init (/Users/air/Projects/node_modules/request/request.js:338:51) 
    at new Request (/Users/air/Projects//node_modules/request/request.js:105:8) 
    at request (/Users/air/Projects/Vertico/Vertico-CLI/node_modules/request/index.js:53:11) 
    at Object.<anonymous> (/Users/air/Projects/req.js:2:1) 
    at Module._compile (module.js:569:30) 
    at Object.Module._extensions..js (module.js:580:10) 
    at Module.load (module.js:503:32) 
    at tryModuleLoad (module.js:466:12) 
    at Function.Module._load (module.js:458:3) 
    at Function.Module.runMain (module.js:605:10) 
statusCode: undefined 
body: undefined 

我修改客户端使用wget壳进程，而不是请求包，该代码是下面，问题是 - 我无法看到wget的良好下载进度，任何解决此代码的方法，以便我可以在子进程中看到进度条。

const fs = require('fs'); 
    const child_process = require('child_process'); 

    var workerProcess = child_process.spawn('wget', ['-O','fdsf.zip', 'http://localhost:11146/base/bigFile.zip']); 

    workerProcess.stdout.on('data', function (data) { 
    console.log('stdout: ' + data); 
    }); 

    workerProcess.stderr.on('data', function (data) { 
    //console.log('stderr: ' + data); 
    }); 

    workerProcess.on('close', function (code) { 
     console.log('Download Completed' + code); 
    }); 

所以最后我想知道如何使用被写入的NodeJS客户端代码下载文件？

Answer 1

最简单的方法是使用request模块

在这里，你试图在内存中存储整个结果和控制台日志它。 5GB非常大，要么增加Node.js内存限制（不推荐），要么必须使用流。见streaming example下面从request NPM文件：

const fs = require('fs'); 
const request = require('request'); 
request('http://google.com/doodle.png').pipe(fs.createWriteStream('doodle.png')) 

必须通过管道的响应，使无论是1MB或1GB或者1TB，只有文件的一小部分会在内存中，它会被写入到磁盘尽快。你可以使用相同的方法使用Node.js内置的函数，但是实现将很困难，并且像request模块在那里时重新发明*一样。

对于下载与进步可以使用request-progress模块request模块一起，见下面的例子（taken from their documentation）：

var fs = require('fs'); 
var request = require('request'); 
var progress = require('request-progress'); 

// The options argument is optional so you can omit it 
progress(request('https://az412801.vo.msecnd.net/vhd/VMBuild_20141027/VirtualBox/IE11/Windows/IE11.Win8.1.For.Windows.VirtualBox.zip'), { 
    // throttle: 2000,     // Throttle the progress event to 2000ms, defaults to 1000ms 
    // delay: 1000,      // Only start to emit after 1000ms delay, defaults to 0ms 
    // lengthHeader: 'x-transfer-length' // Length header to use, defaults to content-length 
}) 
.on('progress', function (state) { 
    // The state is an object that looks like this: 
    // { 
    //  percent: 0.5,    // Overall percent (between 0 to 1) 
    //  speed: 554732,    // The download speed in bytes/sec 
    //  size: { 
    //   total: 90044871,  // The total payload size in bytes 
    //   transferred: 27610959 // The transferred payload size in bytes 
    //  }, 
    //  time: { 
    //   elapsed: 36.235,  // The total elapsed seconds since the start (3 decimals) 
    //   remaining: 81.403  // The remaining seconds to finish (3 decimals) 
    //  } 
    // } 
    console.log('progress', state); 
}) 
.on('error', function (err) { 
    // Do something with err 
}) 
.on('end', function() { 
    // Do something after request finishes 
}) 
.pipe(fs.createWriteStream('IE11.Win8.1.For.Windows.VirtualBox.zip')); 

Answer 2

var request = require('request') 
request('http:/localhost:11146/base/bigFile.zip', function (error, response, body) { 
    console.log('error:', error); // Print the error if one occurred 
    console.log('statusCode:', response && response.statusCode); // Print the response status code if a response was received 
    console.log('body:', body); // Print the HTML for the Google homepage. 
}); 

应该是http://localhost:11146/base/bigFile.zip代替http:/localhost:11146/base/bigFile.zip

Answer 3

我代码版本。

var fs = require('fs'); 
var request = require('request'); 
var progress = require('request-progress'); 
var url = 'http://localhost:4181'; 
var filename = 's.zip'; 
var pre = '----'; 

downloadManager = function(url,filename){ 
    progress(request(url), { 
    throttle:500 
    }) .on('progress', function (state) { 
     process.stdout.write(pre+''+ (Math.round(state.percent*100))+"%"); 
    }) 
    .on('error', function (err) { 
     console.log('error :('+err); 
    }) 
    .on('end', function() { 
     console.log(pre+'100% \n Download Completed'); 
    }) 
    .pipe(fs.createWriteStream(filename)); 
}; 


downloadManager(url,filename);