五.sockit.io

• socket.io 是一个 websocket 库，包括了客户端的 js 和服务端的 nodejs，它的目标是构建可以在不同浏览器和移动设备上使用的实时应用。

1.socket.io 的特点

• 易用性：socket.io 封装了服务端和客户端，使用起来非常简单方便。
• 跨平台：socket.io 支持跨平台，这就意味着你有了更多的选择，可以在自己喜欢的平台下开发实时应用。
• 自适应：它会自动根据浏览器从 websocket、ajax 长轮询、iframe 流等等各种方式中选择最佳的方式来实现网络实时应用，非常方便和人性化，而且支持的浏览器最低达 IE5.5。

2.案例一：web 聊天室

2.1 前端部分

• 用 socket.io 实现一个聊天室

chat.html

index.html

2.2 后端部分

安装部署

• 使用 npm 安装 socket.io

npm install socket.io

server.js

let express = require("express")
let app = express()
let path = require("path")
app.use(express.static(__dirname))
app.get("/", (req, res) => {
  res.sendFile(path.resolve(__dirname, "index.html"))
})
let server = require("http").createServer(app)
server.listen(8080)

//http://localhost:80
//ws://localhost:808
let io = require("socket.io")(server)
//监听客户端的连接
const SYSTEM = "系统"
const ALL_USERS = {}

io.on("connection", async (socket) => {
  let username
  let rooms = []
  socket.on("message", async (message) => {
    if (username) {
      let changeNameReg = /^changename:(.+)$/
      let changeNameResult = message.match(changeNameReg)
      let privateReg = /^@(.+) (.+)$/
      let privateResult = message.match(privateReg)
      if (changeNameResult) {
        let newName = changeNameResult[1]
        io.emit("message", {
          username: SYSTEM,
          content: `用户[${username}]改名为[${newName}]`,
          createAt: new Date(),
        })
        let oldSocket = ALL_USERS[username]
        delete ALL_USERS[username]
        username = newName
        ALL_USERS[username] = oldSocket
      } else if (privateResult) {
        let toUser = privateResult[1]
        let toContent = privateResult[2]
        let toScoket = ALL_USERS[toUser]
        if (toSocket) {
          toSocket.emit("message", {
            username,
            content: toContent,
            createAt: new Date(),
          })
        } else {
          socket.emit("message", {
            username: SYSTEM,
            content: `你想私聊的用户名${toUser}不存在`,
            createAt: new Date(),
          })
        }
      } else {
        let doc = {
          username,
          content: message,
        }

        if (rooms.length > 0) {
          rooms.forEach((room) => {
            io.in(room).emit("message", doc)
          })
        } else {
          io.emit("message", doc)
        }
      }
    } else {
      username = message
      ALL_USERS[username] = socket
      io.emit("message", {
        username: SYSTEM,
        content: `欢迎${username}加入聊天室`,
        createAt: new Date(),
      })
    }
  })
  //加入某个房间 一个客户端可以同时在多个房间内
  socket.on("join", (roomName) => {
    let index = rooms.findIndex((item) => item === roomName)
    if (index == -1) {
      socket.join(roomName)
      rooms.push(roomName)
      socket.emit("message", {
        username: SYSTEM,
        content: `你已经成功的加入到了${roomName}房间内`,
        createAt: new Date(),
      })
      socket.broadcast.to(roomName).emit("message", {
        username: SYSTEM,
        content: `${username}已经成功进入了${roomName}房间`,
        createAt: new Date(),
      })
      //告诉 客户端我已经成功的进入了某个房间
      socket.emit("joined", roomName)
    } else {
      socket.emit("message", {
        username: SYSTEM,
        content: `别闹!你已经在这个房间内了`,
        createAt: new Date(),
      })
    }
  })
  //离开某个房间
  socket.on("leave", (roomName) => {
    let index = rooms.findIndex((item) => item === roomName)
    if (index == -1) {
      socket.emit("message", {
        username: SYSTEM,
        content: `别闹！你根本就不在这个房间内`,
        createAt: new Date(),
      })
    } else {
      socket.leave(roomName)
      rooms.splice(index, 1)
      socket.emit("message", {
        username: SYSTEM,
        content: `你已经成功的离开了${roomName}房间`,
        createAt: new Date(),
      })

      socket.broadcast.to(roomName).emit("message", {
        username: SYSTEM,
        content: `${username}已经成功的离开了${roomName}房间`,
        createAt: new Date(),
      })

      socket.emit("leaved", roomName)
    }
  })

  socket.on("getAllMessages", async () => {
    // let messages=await Message.find().sort({createAt:-1}.limit(20));
    // messages.reverse();
    let message = { msg: "ok" }
    socket.emit("allMessages", messages)
  })

  socket.on("room", (roomName) => {
    let sockets = io.sockets.adapter.rooms[roomName].sockets
    let count = Object.keys(sockets)
  })
})