Node.JS segment resume download: Implementation method of Nginx configuration file segment download function_node.js

This tag can be configured in Node.JS to implement segmented downloading of files. This article introduces you to Node.JS segmented downloading: how to implement the segmented download function of Nginx configuration files. Friends who need it can refer to it

Html5 provides a new Range tag to implement the file. Download in parts. This tag can be configured in Node.JS to implement segmented downloading of files.

Header tag

Request Request Header: Download the file content after 3744

range: bytes=3744-

Return Response Header: The total file length is 15522643 bytes

accept-ranges': 'bytes'
content-range': 'bytes */15522643'

Nginx configuration

First of all, you need to configure Nginx to support range tag return. It is very simple to add add_header Accept-Ranges bytes; this line can

server {
 listen 80;
 server_name adksdf.com;
 location ~ ^/(img/|js/|css/|upload/|font/|fonts/|res/|icon) {
  add_header Access-Control-Allow-Origin *;
  add_header Accept-Ranges bytes;
  root /var/www/...;
  access_log off;
  expires max;
 }
 ...
}

After enabling, if node The .js side sends request information containing range header, then nginx will return range-related information:

This is a complete Response Header. Note that content-length here is not a file. The total length, but the length of the current range.

{ server: 'nginx',
 date: 'Wed, 24 Jan 2018 02:43:20 GMT',
 'content-type': 'application/zip',
 'content-length': '12420187',
 'last-modified': 'Tue, 16 Jan 2018 12:09:47 GMT',
 connection: 'close',
 etag: '"5a5deb8b-ecdb53"',
 expires: 'Thu, 31 Dec 2037 23:55:55 GMT',
 'cache-control': 'max-age=315360000',
 'access-control-allow-origin': '*',
 'accept-ranges': 'bytes',
 'content-range': 'bytes 3102456-15522642/15522643' }

The total size of the file can be obtained based on the content-range in this header.

Node.JS implementation

This example first detects half of the files downloaded locally, and then creates the file in 'r' read-write mode stream and write the response stream to a file.

Here, range support will be added to the statement file.

var reqOptions = { url: packageUrl, headers: {} }
var filepath  = '/path/to/your/part/file'
var fileOptions = {}
fs.stat(filepath, function(err, states) {
 if (states) {
  //Range: bytes=3744-
  reqOptions.headers['range'] = 'bytes=' + states.size + '-'
  fileOptions = { start: states.size, flags: 'r+' }
 }
 //创建 http 对象方法
 var reqUrl = reqOptions.url
 var urlObj = url.parse(reqUrl)
 var options = {
   hostname : urlObj.hostname
  , port   : urlObj.port
  , path   : urlObj.pathname
  , headers  : reqOptions.headers || {}
 }
 var req = http.request(options, function(res) {
  var receives  = []
  var err     = null
  var statusCode = res.statusCode
  var headers   = res.headers
  var ws = fs.createWriteStream(filepath, fileOptions)
  ws.on('error', function(e) {
   console.log('ws error', e)
  })
  res.on('data', function(chrunk) {
   ws.write(chrunk)
  })
  res.on('error', function(err) {
   ws.end()
  })
  res.on('end', function() {
   ws.end()
  })
 })
 req.on('error', function(e) {
  cb && cb(e, null, {})
 })
 req.end()
 ...
})

Return Header

When requesting nginx may return other status codes, such as Say 206 or 416, the meaning is as follows:

206 Partial Content

Returns part of the file content

416 Requested Range Not Satisfiable

The requested range exceeds File size

The above is what I compiled for everyone. I hope it will be helpful to everyone in the future.

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