Skip to main content
Version: 4.x

结束语


结束语

最终服务器代码

index.js
const express = require('express');
const { createServer } = require('node:http');
const { join } = require('node:path');
const { Server } = require('socket.io');
const sqlite3 = require('sqlite3');
const { open } = require('sqlite');
const { availableParallelism } = require('node:os');
const cluster = require('node:cluster');
const { createAdapter, setupPrimary } = require('@socket.io/cluster-adapter');

if (cluster.isPrimary) {
const numCPUs = availableParallelism();
for (let i = 0; i < numCPUs; i++) {
cluster.fork({
PORT: 3000 + i
});
}

return setupPrimary();
}

async function main() {
const db = await open({
filename: 'chat.db',
driver: sqlite3.Database
});

await db.exec(`
CREATE TABLE IF NOT EXISTS messages (
id INTEGER PRIMARY KEY AUTOINCREMENT,
client_offset TEXT UNIQUE,
content TEXT
);
`);

const app = express();
const server = createServer(app);
const io = new Server(server, {
connectionStateRecovery: {},
adapter: createAdapter()
});

app.get('/', (req, res) => {
res.sendFile(join(__dirname, 'index.html'));
});

io.on('connection', async (socket) => {
socket.on('chat message', async (msg, clientOffset, callback) => {
let result;
try {
result = await db.run('INSERT INTO messages (content, client_offset) VALUES (?, ?)', msg, clientOffset);
} catch (e) {
if (e.errno === 19 /* SQLITE_CONSTRAINT */ ) {
callback();
} else {
// nothing to do, just let the client retry
}
return;
}
io.emit('chat message', msg, result.lastID);
callback();
});

if (!socket.recovered) {
try {
await db.each('SELECT id, content FROM messages WHERE id > ?',
[socket.handshake.auth.serverOffset || 0],
(_err, row) => {
socket.emit('chat message', row.content, row.id);
}
)
} catch (e) {
// something went wrong
}
}
});

const port = process.env.PORT;

server.listen(port, () => {
console.log(`server running at http://localhost:${port}`);
});
}

main();

最终客户端代码

index.html
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width,initial-scale=1.0">
<title>Socket.IO chat</title>
<style>
body { margin: 0; padding-bottom: 3rem; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif; }

#form { background: rgba(0, 0, 0, 0.15); padding: 0.25rem; position: fixed; bottom: 0; left: 0; right: 0; display: flex; height: 3rem; box-sizing: border-box; backdrop-filter: blur(10px); }
#input { border: none; padding: 0 1rem; flex-grow: 1; border-radius: 2rem; margin: 0.25rem; }
#input:focus { outline: none; }
#form > button { background: #333; border: none; padding: 0 1rem; margin: 0.25rem; border-radius: 3px; outline: none; color: #fff; }

#messages { list-style-type: none; margin: 0; padding: 0; }
#messages > li { padding: 0.5rem 1rem; }
#messages > li:nth-child(odd) { background: #efefef; }
</style>
</head>
<body>
<ul id="messages"></ul>
<form id="form" action="">
<input id="input" autocomplete="off" /><button>Send</button>
</form>
<script src="/socket.io/socket.io.js"></script>
<script>
let counter = 0;

const socket = io({
ackTimeout: 10000,
retries: 3,
auth: {
serverOffset: 0
}
});

const form = document.getElementById('form');
const input = document.getElementById('input');
const messages = document.getElementById('messages');

form.addEventListener('submit', (e) => {
e.preventDefault();
if (input.value) {
const clientOffset = `${socket.id}-${counter++}`;
socket.emit('chat message', input.value, clientOffset);
input.value = '';
}
});

socket.on('chat message', (msg, serverOffset) => {
const item = document.createElement('li');
item.textContent = msg;
messages.appendChild(item);
window.scrollTo(0, document.body.scrollHeight);
socket.auth.serverOffset = serverOffset;
});
</script>
</body>
</html>

家庭作业

以下是改进应用的一些想法:

英:Here are some ideas to improve the application:

  • 当有人连接或断开连接时,向已连接的用户广播消息。
  • 添加对昵称的支持。
  • 不要向发送该消息的用户发送相同的消息。 而是,只要他们按下 Enter 键,就直接附加消息。
  • 添加 “{user} 正在打字” 功能。
  • 显示谁在线。
  • 添加私有消息。
  • 分享你的改进!

获取这个例子

你可以在 GitHub 此处 上找到它。

英:You can find it on GitHub here.

git clone https://github.com/socketio/chat-example.git

下一步

请查看:

英:Please check out: