通过请求在 Node.js 中获取下载进度

Question

我正在创建一个使用 Node 模块 request 下载应用程序文件的更新程序。如何使用chunk.length 估算剩余文件大小？这是我的部分代码：

var file_url = 'http://foo.com/bar.zip';
var out = fs.createWriteStream('baz.zip');

var req = request({
    method: 'GET',
    uri: file_url
});

req.pipe(out);

req.on('data', function (chunk) {
    console.log(chunk.length);
});

req.on('end', function() {
    //Do something
});

Answer 1

这应该可以得到你想要的总数：

req.on( 'response', function ( data ) {
    console.log( data.headers[ 'content-length' ] );
} );

我得到9404541的内容长度

Answer 2

function download(url, callback, encoding){
        var request = http.get(url, function(response) {
            if (encoding){
                response.setEncoding(encoding);
            }
            var len = parseInt(response.headers['content-length'], 10);
            var body = "";
            var cur = 0;
            var obj = document.getElementById('js-progress');
            var total = len / 1048576; //1048576 - bytes in  1Megabyte

            response.on("data", function(chunk) {
                body += chunk;
                cur += chunk.length;
                obj.innerHTML = "Downloading " + (100.0 * cur / len).toFixed(2) + "% " + (cur / 1048576).toFixed(2) + " mb\r" + ".<br/> Total size: " + total.toFixed(2) + " mb";
            });

            response.on("end", function() {
                callback(body);
                obj.innerHTML = "Downloading complete";
            });

            request.on("error", function(e){
                console.log("Error: " + e.message);
            });

        });
    };

Answer 3

我写了一个模块来做你想做的事：status-bar。

var bar = statusBar.create ({ total: res.headers["content-length"] })
    .on ("render", function (stats){
      websockets.send (stats);
    })

req.pipe (bar);

Answer 4

使用酷炫的 node-request-progress 模块，你可以在 es2015 中做这样的事情：

import { createWriteStream } from 'fs'
import request from 'request'
import progress from 'request-progress'

progress(request('http://foo.com/bar.zip'))
 .on('progress', state => {

   console.log(state)

   /*
   {
       percentage: 0.5,        // Overall percentage (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)
       }
   }
   */

  })
  .on('error', err => console.log(err))
  .on('end', () => {})
  .pipe(createWriteStream('bar.zip'))

Answer 5

如果有人想知道进度而不使用其他库而只请求，那么您可以使用以下方法：

function downloadFile(file_url , targetPath){
    // Save variable to know progress
    var received_bytes = 0;
    var total_bytes = 0;

    var req = request({
        method: 'GET',
        uri: file_url
    });

    var out = fs.createWriteStream(targetPath);
    req.pipe(out);

    req.on('response', function ( data ) {
        // Change the total bytes value to get progress later.
        total_bytes = parseInt(data.headers['content-length' ]);
    });

    req.on('data', function(chunk) {
        // Update the received bytes
        received_bytes += chunk.length;

        showProgress(received_bytes, total_bytes);
    });

    req.on('end', function() {
        alert("File succesfully downloaded");
    });
}

function showProgress(received,total){
    var percentage = (received * 100) / total;
    console.log(percentage + "% | " + received + " bytes out of " + total + " bytes.");
    // 50% | 50000 bytes received out of 100000 bytes.
}

downloadFile("https://static.pexels.com/photos/36487/above-adventure-aerial-air.jpg","c:/path/to/local-image.jpg");

received_bytes 变量保存每个发送的块长度的总和，并根据total_bytes 检索进度。

Answer 6

如果你正在使用“请求”模块，并且想在不使用任何额外模块的情况下显示下载百分比，可以使用以下代码：

function getInstallerFile (installerfileURL,installerfilename) {

    // Variable to save downloading progress
    var received_bytes = 0;
    var total_bytes = 0;

    var outStream = fs.createWriteStream(installerfilename);
    
    request
        .get(installerfileURL)
            .on('error', function(err) {
                console.log(err);
            })
            .on('response', function(data) {
                total_bytes = parseInt(data.headers['content-length']);
            })
            .on('data', function(chunk) {
                received_bytes += chunk.length;
                showDownloadingProgress(received_bytes, total_bytes);
            })
            .pipe(outStream);
};

function showDownloadingProgress(received, total) {
    var platform = "win32"; // Form windows system use win32 for else leave it empty
    var percentage = ((received * 100) / total).toFixed(2);
    process.stdout.write((platform == 'win32') ? "\033[0G": "\r");
    process.stdout.write(percentage + "% | " + received + " bytes downloaded out of " + total + " bytes.");
}

用法：

getInstallerFile("http://example.com/bar.zip","bar.zip");