文章目录
- 演示
- 大纲
- 基础 WebSocket
- 前端: 添加心跳机制
- 前端: 尝试重新连接
- 历史代码
还没有写完，bug 是有的，我在想解决办法了…
演示
大纲
- 基础的 webSocket 连接
- 前后端：添加心跳机制
- 后端无心跳反应，前端尝试重新连接
- 设置重新连接次数，超过最大尝试次数之后，不再尝试重新连接
基础 WebSocket
前端的基础就是这些，大概的效果是这样的
<body><button onclick="reConnect()">1. 重建连接</button><button onclick="sendMessage()">2. 发消息</button><button onclick="stopConnect()">3. 断开连接</button>
</body>
<script>let ws = null // 使用null来标记当前没有活动的 WebSocket 连接function createNewWebSocket() {if (ws && ws.readyState !== WebSocket.CLOSED) {ws.close() // 确保关闭旧的连接}ws = new WebSocket('ws://localhost:8080')ws.onopen = function (evt) {console.log('Connection open ...')}ws.onmessage = function (evt) {console.log('Received Message: ' + evt.data)}ws.onclose = function (evt) {console.log('Connection closed.')}}function sendMessage() {if (ws) ws.send(`前端发送:>> ${new Date()}`)}function stopConnect() {if (ws) ws.close()}function reConnect() {createNewWebSocket()}
</script>
后端的代码基本不变，所以我直接把心跳也做好
后端的心跳就是：拿到前端的值，如果是ping的话，就返回一个pong，其他逻辑保持不变
const http = require('http')
const WebSocket = require('ws')
const server = http.createServer()
const wss = new WebSocket.Server({ server })wss.on('connection', (socket) => {console.log('webSocket 连接成功')socket.on('message', (message) => {// 将 Buffer 转换为字符串const messageStr = message.toString()const currentRandom = Math.random()const isSendPong = currentRandom < 0.5console.log('后端收到消息:>>' + messageStr)// 检查是否为心跳请求if (messageStr === 'ping') {socket.send(`当前随机值为 ${currentRandom}, 是否发送心跳：${isSendPong}`)// 50%的概率发送 "pong"if (isSendPong) {socket.send('pong') // 心跳响应}} else {const message = `后端发送消息:>> 你好前端~ ${new Date().toLocaleString()}`socket.send(message)}})socket.on('close', () => {console.log('websocket 已经关闭')})
})server.on('request', (request, response) => {response.writeHead(200, { 'Content-Type': 'text/plain' })response.end('Hello, World')
})server.listen(8080, () => {console.log('服务器已启动，端口号为 8080')
})前端: 添加心跳机制
思路：前端写一个定时器，用于隔一段时间发送一个
ping值
效果如下图所示
好吧，false 的概率有点高，不顾可以看历史记录
我在后端设置了随机逻辑，模拟一下出错的场景，百分之50的概率回应前端的心跳，如果 true 的话，后端就回应前端的心跳，返回 pong
前端 代码如下
<body><button onclick="reConnect()">1. 重建连接</button><button onclick="sendMessage()">2. 发消息</button><button onclick="stopConnect()">3. 断开连接</button>
</body>
<script>let ws = null // 使用null来标记当前没有活动的 WebSocket 连接let heartbeatTimer = null // 心跳定时器const HEARTBEAT_INTERVAL = 5000 // 每隔 5 秒发送一次心跳function createNewWebSocket() {if (ws && ws.readyState !== WebSocket.CLOSED) {ws.close() // 确保关闭旧的连接}ws = new WebSocket('ws://localhost:8080')ws.onopen = function (evt) {console.log('Connection open ...')startHeartbeat()}ws.onmessage = function (evt) {console.log('Received Message: ' + evt.data)handleHeartbeatResponse(evt.data)}ws.onclose = function (evt) {console.log('Connection closed.')stopHeartbeat()}}function sendMessage() {if (ws) ws.send(`前端发送:>> ${new Date().toLocaleString()}`)}function stopConnect() {if (ws) ws.close()stopHeartbeat()}function reConnect() {createNewWebSocket()}function startHeartbeat() {heartbeatTimer = setInterval(() => {ws.send('ping')}, HEARTBEAT_INTERVAL)}function stopHeartbeat() {clearInterval(heartbeatTimer)heartbeatTimer = null}function handleHeartbeatResponse(message) {if (message === 'heartbeat') {console.log('Heartbeat received.')clearTimeout(heartbeatTimer) // 清除超时定时器startHeartbeat() // 重新启动心跳}}
</script>
前端: 尝试重新连接
设置一个场景: 前端发送三个心跳包，如果都没有反应，那么就判断为断开连接了，就去重新连接
历史代码
前端
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8" /><meta name="viewport" content="width=device-width, initial-scale=1.0" /><title>Document</title></head><body><button id="btn">发消息</button><button id="stop">断链</button><button id="reconnect">重新连接</button></body><script>const btn = document.querySelector('#btn')const stop = document.querySelector('#stop')const reconnect = document.querySelector('#reconnect')let ws = null // 使用null来标记当前没有活动的WebSocket连接let heartbeatInterval = null // 存储心跳定时器let timeoutId = null // 存储超时定时器let reconnectAttempts = 0 // 重连尝试次数const maxReconnectAttempts = 3 // 最大重连次数function createNewWebSocket() {if (ws && ws.readyState !== WebSocket.CLOSED) {ws.close() // 确保关闭旧的连接}ws = new WebSocket('ws://localhost:8080')ws.onopen = function (evt) {console.log('Connection open ...')startHeartbeat() // 开始发送心跳}ws.onmessage = function (evt) {console.log('Received Message: ' + evt.data)// 检查是否为心跳响应if (evt.data === 'pong') {clearTimeout(timeoutId) // 清除超时定时器resetHeartbeatTimer() // 重置心跳定时器}}ws.onclose = function (evt) {console.log('Connection closed.')clearInterval(heartbeatInterval) // 清除心跳定时器reconnectWebSocket() // 尝试重新连接}}// 发送心跳包function sendHeartbeat() {if (ws) {ws.send('ping')timeoutId = setTimeout(() => {// 如果在超时时间内没有收到 "pong" 响应，则关闭当前连接console.log('超时，关闭连接')ws.close()}, 15000) // 设置超时时间为 15 秒}}// 启动心跳function startHeartbeat() {sendHeartbeat() // 立即发送第一个心跳包heartbeatInterval = setInterval(sendHeartbeat, 30000) // 每30秒发送一次}// 重置心跳定时器function resetHeartbeatTimer() {clearInterval(heartbeatInterval)heartbeatInterval = setInterval(sendHeartbeat, 30000) // 重新设置定时器}// 重新连接function reconnectWebSocket() {console.log('尝试重新连接', reconnectAttempts)// 检查是否超过最大重连次数if (reconnectAttempts < maxReconnectAttempts) {reconnectAttempts++createNewWebSocket()} else {console.log('超过最大重连次数，不再尝试连接')}}btn.addEventListener('click', () => {if (ws) {ws.send(`前端发送:>> ${new Date()}`)}})stop.addEventListener('click', () => {if (ws) {ws.close()}})reconnect.addEventListener('click', () => {createNewWebSocket()})</script>
</html>后端
const http = require('http')
const WebSocket = require('ws')
const server = http.createServer()
const wss = new WebSocket.Server({ server })wss.on('connection', (socket) => {console.log('webSocket 连接成功')socket.on('message', (message) => {// 将 Buffer 转换为字符串const messageStr = message.toString();console.log('后端收到消息:>>' + messageStr);// 检查是否为心跳请求if (messageStr === 'ping') {socket.send('pong'); // 心跳响应} else {socket.send('后端发送消息:>> hello 我是 socket.send');}})socket.on('close', () => {console.log('websocket 已经关闭');})
})server.on('request', (request, response) => {response.writeHead(200, { 'Content-Type': 'text/plain' });response.end('Hello, World');
})server.listen(8080, () => {console.log('服务器已启动，端口号为 8080');
})
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