socket.io 判断用户在线还是离线

Question

我们可以通过此代码跟踪连接是建立还是断开

console.log('a user connected');
    socket.on('disconnect', function () {
        console.log('user disconnected');
    });

嗯，很好。但是我们如何确定哪些用户已连接或离线。我的客户端是用 PHP/HTML 编写的，所以他们有一个用户 ID。

Answer 1

如果您的客户有特定的用户 ID，他们需要将它们发送到 socket.io 服务器。例如。在客户端你可以做

// Browser (front-end)
<script>
 const socket = io();
 socket.emit('login',{userId:'YourUserID'});
</script>

在服务器上你会放一些类似

的东西

// server (back-end)
const users = {};
io.on('connection', function(socket){
  console.log('a user connected');

  socket.on('login', function(data){
    console.log('a user ' + data.userId + ' connected');
    // saving userId to object with socket ID
    users[socket.id] = data.userId;
  });

  socket.on('disconnect', function(){
    console.log('user ' + users[socket.id] + ' disconnected');
    // remove saved socket from users object
    delete users[socket.id];
  });
});

现在您可以将套接字 ID 与您的用户 ID 配对并使用它。

Answer 2

除了@galethil 的回答，如果用户打开多个选项卡 （套接字连接），每个选项卡 （套接字连接） 具有单个用户的唯一套接字 ID，因此我们需要为特定用户管理套接字 ID 数组，

客户端连接： 支持Socket IO Client v3.x,

<!-- SOCKET LIBRARY IN HTML -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/socket.io/3.0.5/socket.io.js"></script>

const host = "http://yourdomain.com";
// PASS your query parameters
const queryParams = { userId: 123 };
const socket = io(host, {
    path: "/pathToConnection",
    transports: ['websocket'],  // 
    upgrade: false,
    query: queryParams,
    reconnection: false,
    rejectUnauthorized: false
});

socket.once("connect", () => {
    
    // USER IS ONLINE
    socket.on("online", (userId) => {
        console.log(userId, "Is Online!"); // update online status
    });

    // USER IS OFFLINE
    socket.on("offline", (userId) => {
        console.log(userId, "Is Offline!"); // update offline status
    });

});

服务器端连接：支持Socket IO Server v3.x，

依赖关系：

const _ = require("lodash");
const express = require('express');
const app = express();
const port = 3000; // define your port
const server = app.listen(port, () => {
  console.log(`We are Listening on port ${port}...`);
});

连接：

const io = require('socket.io')(server, {
    path: "/pathToConnection"
});
let users = {};
io.on('connection', (socket) => {

  let userId = socket.handshake.query.userId; // GET USER ID
  
  // CHECK IS USER EXHIST 
  if (!users[userId]) users[userId] = [];
  
  // PUSH SOCKET ID FOR PARTICULAR USER ID
  users[userId].push(socket.id);
   
  // USER IS ONLINE BROAD CAST TO ALL CONNECTED USERS
  io.sockets.emit("online", userId);

  // DISCONNECT EVENT
  socket.on('disconnect', (reason) => {

    // REMOVE FROM SOCKET USERS
    _.remove(users[userId], (u) => u === socket.id);
    if (users[userId].length === 0) {
      // ISER IS OFFLINE BROAD CAST TO ALL CONNECTED USERS
      io.sockets.emit("offline", userId);
      // REMOVE OBJECT
      delete users[userId];
    }
   
    socket.disconnect(); // DISCONNECT SOCKET

  });

});

GitHub Demo

Answer 3

我们可以识别服务器中的socket id，谁连接了，谁断开了。所以你可以做这样的事情。如果您在客户端有标识符，则可以使用此设置

客户

socket.emit('login', userId);

服务器端

const users = {};
io.on("connection", (socket) => {

   socket.on("login", (data) => {
      users[socket.id] = data;
    });

  socket.on("disconnecting", (reason) => {
    
    delete users[socket.id]; // remove the user. -- maybe not the exact code
  });
});

希望你明白了。

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