我们可以通过这段代码来追踪连接是建立还是断开
console.log('a user connected');
socket.on('disconnect', function () {
console.log('user disconnected');
});
嗯，没关系。但是我们如何确定哪些用户连接或离线。我的客户是用PHP/HTML写的，所以他们有一个用户ID。
【问题讨论】：
标签： node.js websocket socket.io real-time
如果您的客户端有特定的用户 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
<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
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。
【讨论】：
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） 对单个用户都有唯一的套接字ID 怎么办？ ，所以我们需要管理特定用户的套接字 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'], // https://stackoverflow.com/a/52180905/8987128
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，
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}...`);
});
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
});
});
【讨论】：
我们可以识别服务器中的socket id，谁是连接的，谁是断开的。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
});
});
希望你能明白。
【讨论】：