前面已经学习了WebSocket API，包括事件、方法和属性。详情：WebSocket(二)--API WebSocket是基于事件驱动，支持全双工通信。下面通过三个简单例子体验一下。
简单开始
1.安装node。https://nodejs.org/en/
2.安装ws模块
ws：是nodejs的一个WebSocket库，可以用来创建服务。 https://github.com/websockets/ws
3.server.js
在项目里面新建一个server.js，创建服务，指定8181端口，将收到的消息log出来。
var WebSocketServer = require(‘ws‘).Server,wss = new WebSocketServer({ port: 8181 });wss.on(‘connection‘, function (ws) { ???console.log(‘client connected‘); ???ws.on(‘message‘, function (message) { ???????console.log(message); ???});});4.建立一个client.html。
在页面上建立一个WebSocket的连接。用send方法发送消息。
var ws = new WebSocket("ws://localhost:8181"); ???ws.onopen = function (e) { ???????console.log(‘Connection to server opened‘); ???} ???function sendMessage() { ???????ws.send($(‘#message‘).val()); ???}页面：
View Code
运行之后如下，服务端即时获得客户端的消息。
模拟股票
上面的例子很简单，只是为了演示如何运用nodejs的ws创建一个WebSocket服务器。且可以接受客户端的消息。那么下面这个例子演示股票的实时更新。客服端只需要连接一次，服务器端会不断地发送新数据，客户端收数据后更新UI.页面如下，有五只股票，开始和停止按钮测试连接和关闭。
服务端：
1.模拟五只股票的涨跌。
var stocks = { ???"AAPL": 95.0, ???"MSFT": 50.0, ???"AMZN": 300.0, ???"GOOG": 550.0, ???"YHOO": 35.0}function randomInterval(min, max) { ???return Math.floor(Math.random() * (max - min + 1) + min);}var stockUpdater;var randomStockUpdater = function() { ???for (var symbol in stocks) { ???????if(stocks.hasOwnProperty(symbol)) { ???????????var randomizedChange = randomInterval(-150, 150); ???????????var floatChange = randomizedChange / 100; ???????????stocks[symbol] += floatChange; ???????} ???} ???var randomMSTime = randomInterval(500, 2500); ???stockUpdater = setTimeout(function() { ???????randomStockUpdater(); ???}, randomMSTime);}randomStockUpdater();2.连接建立之后就开始更新数据
wss.on(‘connection‘, function (ws) { ???var sendStockUpdates = function (ws) { ???????if (ws.readyState == 1) { ???????????var stocksObj = {}; ???????????for (var i = 0; i < clientStocks.length; i++) { ?????????????var symbol = clientStocks[i]; ???????????????stocksObj[symbol] = stocks[symbol]; ???????????} ???????????if (stocksObj.length !== 0) { ???????????????ws.send(JSON.stringify(stocksObj));//需要将对象转成字符串。WebSocket只支持文本和二进制数据 ???????????????console.log("更新", JSON.stringify(stocksObj)); ???????????} ??????????????????} ???} ???var clientStockUpdater = setInterval(function () { ???????sendStockUpdates(ws); ???}, 1000); ???ws.on(‘message‘, function (message) { ???????var stockRequest = JSON.parse(message);//根据请求过来的数据来更新。 ???????console.log("收到消息", stockRequest); ???????clientStocks = stockRequest[‘stocks‘]; ???????sendStockUpdates(ws); ???});客户端：
建立连接：
var ws = new WebSocket("ws://localhost:8181");onopen直接只有在连接成功后才会触发，在这个时候将客户端需要请求的股票发送给服务端。
var isClose = false; ???var stocks = { ???????"AAPL": 0, "MSFT": 0, "AMZN": 0, "GOOG": 0, "YHOO": 0 ???}; ???function updataUI() { ???????ws.onopen = function (e) { ???????????console.log(‘Connection to server opened‘); ???????????isClose = false; ???????????ws.send(JSON.stringify(stock_request)); ???????????console.log("sened a mesg"); ???????} ???????//更新UI ???????var changeStockEntry = function (symbol, originalValue, newValue) { ???????????var valElem = $(‘#‘ + symbol + ‘ span‘); ???????????valElem.html(newValue.toFixed(2)); ???????????if (newValue < originalValue) { ???????????????valElem.addClass(‘label-danger‘); ???????????????valElem.removeClass(‘label-success‘); ???????????} else if (newValue > originalValue) { ???????????????valElem.addClass(‘label-success‘); ???????????????valElem.removeClass(‘label-danger‘); ???????????} ???????} ???????// 处理受到的消息 ???????ws.onmessage = function (e) { ???????????var stocksData = JSON.parse(e.data); ???????????console.log(stocksData); ???????????for (var symbol in stocksData) { ???????????????if (stocksData.hasOwnProperty(symbol)) { ???????????????????changeStockEntry(symbol, stocks[symbol], stocksData[symbol]); ???????????????????stocks[symbol] = stocksData[symbol]; ???????????????} ???????????} ???????}; ???} ???updataUI();运行效果如下：只需要请求一次，数据就会不断的更新，效果是不是很赞，不用轮询，也不用长连接那么麻烦了。文章末尾会附上所有源码。
（美股的涨跌和A股的颜色是反的，即红跌绿涨）
实时聊天
上面的例子是连接建立之后，服务端不断给客户端发送数据。接下来例子是一个简单的聊天室类的例子。可以建立多个连接。
1.安装node-uuid模块，用来给每个连接一个唯一号。
2.服务端消息发送
消息类型分notification和message两种，前者是提示信息，后者是聊天内容。消息还包含一个id、昵称和消息内容。在上一节有学习到readyState有四个值，OPEN表示连接建立可以发送消息。如果页面关闭了，为WebSocket.CLOSE。
function wsSend(type, client_uuid, nickname, message) { ???for (var i = 0; i < clients.length; i++) { ???????var clientSocket = clients[i].ws; ???????if (clientSocket.readyState === WebSocket.OPEN) { ???????????clientSocket.send(JSON.stringify({ ???????????????"type": type, ???????????????"id": client_uuid, ???????????????"nickname": nickname, ???????????????"message": message ???????????})); ???????} ???}}3.服务端处理连接
每新增加一个连接，都会发送一条匿名用户的加入的提示消息，如果消息中带有“/nick” 认为这一个修改昵称的消息。然后更新客户端的昵称。其他都会当做聊天消息处理。
wss.on(‘connection‘, function(ws) { ???var client_uuid = uuid.v4(); ???var nickname = "AnonymousUser" + clientIndex; ???clientIndex += 1; ???clients.push({ "id": client_uuid, "ws": ws, "nickname": nickname }); ???console.log(‘client [%s] connected‘, client_uuid); ???var connect_message = nickname + " has connected"; ???wsSend("notification", client_uuid, nickname, connect_message); ???console.log(‘client [%s] connected‘, client_uuid); ???ws.on(‘message‘, function(message) { ???????if (message.indexOf(‘/nick‘) === 0) { ???????????var nickname_array = message.split(‘ ‘); ???????????if (nickname_array.length >= 2) { ???????????????var old_nickname = nickname; ???????????????nickname = nickname_array[1]; ???????????????var nickname_message = "Client " + old_nickname + " changed to " + nickname; ???????????????wsSend("nick_update", client_uuid, nickname, nickname_message); ???????????} ???????} else { ???????????wsSend("message", client_uuid, nickname, message); ???????} ???});处理连接关闭：
?var closeSocket = function(customMessage) { ???????for (var i = 0; i < clients.length; i++) { ???????????if (clients[i].id == client_uuid) { ???????????????var disconnect_message; ???????????????if (customMessage) { ???????????????????disconnect_message = customMessage; ???????????????} else { ???????????????????disconnect_message = nickname + " has disconnected"; ???????????????} ???????????????wsSend("notification", client_uuid, nickname, disconnect_message); ???????????????clients.splice(i, 1); ???????????} ???????} ???}; ???ws.on(‘close‘, function () { ???????closeSocket(); ???});4.客户端
没有启动时，页面如下，change按钮用来修改昵称。
<div class="vertical-center"> ???????<div class="container"> ???????????<ul id="messages" class="list-unstyled"></ul> ???????????<hr/> ???????????<form role="form" id="chat_form" onsubmit="sendMessage(); return false;"> ???????????????<div class="form-group"> ???????????????????<input class="form-control" type="text" id="message" name="message" ??????????????????????????placeholder="Type text to echo in here" value="" autofocus/> ???????????????</div> ???????????????<button type="button" id="send" class="btn btn-primary" ???????????????????????onclick="sendMessage();"> ???????????????????Send Message ???????????????</button> ???????????</form> ???????????<div class="form-group"><span>nikename：</span><input id="name" type="text" /> <button class="btn btn-sm btn-info" onclick="changName();">change</button></div> ???????</div> ???</div>
js:
??//建立连接 ???????var ws = new WebSocket("ws://localhost:8181"); ???????var nickname = ""; ???????ws.onopen = function (e) { ???????????console.log(‘Connection to server opened‘); ???????} ???????//显示 ???????function appendLog(type, nickname, message) { ???????????if (typeof message == "undefined") return; ???????????var messages = document.getElementById(‘messages‘); ???????????var messageElem = document.createElement("li"); ???????????var preface_label; ???????????if (type === ‘notification‘) { ???????????????preface_label = "<span class=\"label label-info\">*</span>"; ???????????} else if (type == ‘nick_update‘) { ???????????????preface_label = "<span class=\"label label-warning\">*</span>"; ???????????} else { ???????????????preface_label = "<span class=\"label label-success\">" ???????????????+ nickname + "</span>"; ???????????} ???????????var message_text = "<h2>" + preface_label + " " ???????????+ message + "</h2>"; ???????????messageElem.innerHTML = message_text; ???????????messages.appendChild(messageElem); ???????} ???????//收到消息处理 ???????ws.onmessage = function (e) { ???????????var data = JSON.parse(e.data); ???????????nickname = data.nickname; ???????????appendLog(data.type, data.nickname, data.message); ???????????console.log("ID: [%s] = %s", data.id, data.message); ???????} ???????ws.onclose = function (e) { ???????????appendLog("Connection closed"); ???????????console.log("Connection closed"); ???????} ???????//发送消息 ???????function sendMessage() { ???????????var messageField = document.getElementById(‘message‘); ???????????if (ws.readyState === WebSocket.OPEN) { ???????????????ws.send(messageField.value); ???????????} ???????????messageField.value = ‘‘; ???????????messageField.focus(); ???????} ???????//修改名称 ???????function changName() { ???????????var name = $("#name").val(); ???????????if (ws.readyState === WebSocket.OPEN) { ???????????????ws.send("/nick " + name); ???????????} ???????}运行结果：
页面关闭之后，连接马上断开。
这种实时响应的体验简直不能太爽，代码也清爽了，前端体验也更好，客户端不用一直发请求，服务端不用等着被轮询。
小结：上面例子的代码都很好理解，接下来学习WebSocket协议。
源码：http://pan.baidu.com/s/1c2FfKbA
源码：http://pan.baidu.com/s/1o8KRmUQ 加入了socket.io的实现。
API：WebSocket API
相关：websoket使用Protocol Buffers3.0传输
本文摘自：http://www.cnblogs.com/stoneniqiu/p/5402311.html
原创作者：stoneniqiu
WebSocket 学习(三)--用nodejs搭建服务器
原文地址：https://www.cnblogs.com/momoyan/p/9128052.html