Express.js - app.listen 与 server.listen [英] Express.js - app.listen vs server.listen

问题描述

这可能是一个非常基本的问题，但我就是不明白.使用 Express.js 创建应用程序和启动应用程序侦听端口 1234 有什么区别，例如:

This may be a very basic question but I simply don't get it. What is the difference between creating an app using Express.js and starting the app listening on port 1234, for example:

var express = require('express');
var app = express();

//app.configure, app.use etc

app.listen(1234);

并添加一个 http 服务器:

and adding an http server:

var express = require('express');
var http = require('http');

var app = express();
var server = http.createServer(app);

//app.configure, app.use etc

server.listen(1234);

有什么区别?
如果我导航到 http://localhost:1234，我会得到相同的输出.

What's the difference?
If I navigate to http://localhost:1234, thus I get the same output.

推荐答案

第二种形式(自己创建一个 HTTP 服务器，而不是让 Express 为你创建一个)对于重用 HTTP 服务器很有用，例如在同一个 HTTP 服务器实例中运行 socket.io:

The second form (creating an HTTP server yourself, instead of having Express create one for you) is useful if you want to reuse the HTTP server, for example to run socket.io within the same HTTP server instance:

var express = require('express');
var app     = express();
var server  = require('http').createServer(app);
var io      = require('socket.io').listen(server);
...
server.listen(1234);

然而，app.listen() 也返回 HTTP 服务器实例，所以通过一些重写，你可以实现类似的东西，而无需自己创建 HTTP 服务器:

However, app.listen() also returns the HTTP server instance, so with a bit of rewriting you can achieve something similar without creating an HTTP server yourself:

var express   = require('express');
var app       = express();

// app.use/routes/etc...

var server    = app.listen(3033);
var io        = require('socket.io').listen(server);

io.sockets.on('connection', function (socket) {
  ...
});

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