Node module request
を使用してアプリケーションファイルをダウンロードするアップデーターを作成しています。使用方法chunk.length
残りのファイルサイズを推定するには?コードの一部を次に示します。
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
});
これにより、必要な合計が得られます。
req.on( 'response', function ( data ) {
console.log( data.headers[ 'content-length' ] );
} );
コンテンツの長さは9404541
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);
});
});
};
Cool node-request-progress モジュールを使用すると、es2015で次のようなことができます。
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'))
「リクエスト」モジュールを使用しており、追加のモジュールを使用せずにダウンロード率を表示する場合は、次のコードを使用できます。
function getInstallerFile (installerfileURL) {
// Variable to save downloading progress
var received_bytes = 0;
var total_bytes = 0;
var outStream = fs.createWriteStream(INSTALLER_FILE);
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 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.");
}
必要なことだけを行うモジュールを作成しました: status-bar 。
var bar = statusBar.create ({ total: res.headers["content-length"] })
.on ("render", function (stats){
websockets.send (stats);
})
req.pipe (bar);
誰かが他のライブラリを使用せずに進行状況を知りたいだけでリクエストしたい場合は、次のメソッドを使用できます:
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
変数は、送信されたすべてのチャンク長の合計を保存し、total_bytes
、進行状況が取得されます。