socket.io供应了基于事宜的及时双向通信

服务端与客户端衔接

socket.io同时供应了服务端和客户端的API

服务端socket.io必需绑定一个http.Server实例

绑定http.Server

1. 隐式绑定

经由过程实例化时传入端口或实例化后挪用listen或attach函数举行隐式绑定。socket.io内部实例化并监听http.Server

• 实例化时传入端口

let io = require('socket.io')(3000)

• 直接经由过程listen或attach函数绑定。listen与attach同义

let io = require('socket.io')
io.listen(3000) // io.attach(3000) 

1. 显现绑定

能够手动指定http.Server

• 实例化时绑定

let server = require('http').Server();
let io = require('socket.io')(server)

server.listen(3000)

• 经由过程listen或attach绑定

let server = require('http').Server();
let io = require('socket.io')()

io.listen(server) // io.attach(server)

server.listen(3000)

• 能够绑定express或koa等http框架

express

let app = require('express')
let server = require('http').Server(app)
let io = require('socket.io')(server)

app.listen(3000)

koa

let app = require('koa')()
let server = require('http').Server(app.callback())

let io = require('socket.io')(server)

app.listen(3000)

监听衔接状况

当服务器端与客户端衔接胜利时，服务端会监听到connection和connect事宜(connection与connect同义), 客户端会监听到connect事宜, 断开衔接时服务端的对应到客户端的socket与客户端均会均会监听到disconnect事宜

服务端代码

let server = require('http').Server()
let io = require('socket.io')(server)

server.listen(3000);
io.on('connection', socket => {
  console.log('connect')
  socket.on('disconnect', () => {
    console.log('disconnect')
  })
  socket.disconnect()
})

运转后打印

connect
disconnect

客户端代码

let socket = io('http://localhost:3000')
socket.on('connect', () => {
  console.log('connect')
})
socket.on('disconnect', () => {
  console.log('disconnect')
})

运转后打印

connect
disconnect

传输数据

服务器与客户端的socket是一个关联的EventEmitter对象，客户端socket派发的事宜能够通以被服务端的socket吸收，服务器端socket派发的事宜也能够被客户端接收。基于这类机制，能够完成双向交流。

如今模仿如许一种状况：客户端不断发送随机数，当随机数大于0.95时，服务端延时1s后向客户端发送正告以及正告次数

服务端代码

let server = require('http').Server()
let io = require('socket.io')(server)

server.listen(3000);
io.on('connection', socket => {
  socket.on('random', value => {
    console.log(value)
    if (value > 0.95) {
      if (typeof socket.warning === 'undefined') socket.warning = 0
      setTimeout(() => {
        socket.emit('warn', ++socket.warning)
      }, 1000)
    }
  })
})

socket对象能够用来存储状况信息和自定义数据,如socket.warning

客户端代码

let socket = io('http://localhost:3000')
let interval = setInterval(() => {
  socket.emit('random', Math.random())
}, 500)
socket.on('warn', count => {
  console.log('warning count: ' + count)
})
socket.on('disconnect', () => {
  clearInterval(interval)
})

传输流

socket.io能够处置惩罚流

服务端代码

io.on('connection', function (socket) {
  let stream = ss.createStream()
  ss(socket).emit('script', stream)
  fs.createReadStream(__filename).pipe(stream)
})

客户端代码

let socket = io('http://localhost:3000') 
ss(socket).on('script', stream => {
  let buffer = '' 
  stream.on('data', data => {
    buffer += data.toString()
  })
  stream.on('end', () => {
    console.log(buffer)
  })
})

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