WebSocket 学习(三)--用nodejs搭建服务器


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:

<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>WebSocket Echo Demo</title>
<meta name="viewport" content="width=device-width, initial-scale=1"/>
<link href="../bootstrap-3.3.5/css/bootstrap.min.css" rel="stylesheet" />
<script src="../js/jquery-1.12.3.min.js"></script>
<script src="../js/jquery-1.12.3.min.js"></script>
<script src="../bootstrap-3.3.5/js/bootstrap.min.js"></script>
<script>
var ws = new WebSocket("ws://localhost:8181");
ws.onopen
= function (e) {
console.log(
'Connection to server opened');
}
function sendMessage() {
ws.send($(
'#message').val());
}
</script>
</head>

<body >
<div class="vertical-center">
<div class="container">
<p>&nbsp;</p>
<form role="form" id="chat_form" onsubmit="sendMessage(); return false;">
<div class="form-group">
<input class="form-control" type="text" name="message" id="message"
placeholder
="Type text to echo in here" value="" />
</div>
<button type="button" id="send" class="btn btn-primary"
onclick
="sendMessage();">
Send!
</button>
</form>
</div>
</div>
</body>
</html>
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>
View Code

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 + "&nbsp;&nbsp;"
+ 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

智能推荐

注意!

本站转载的文章为个人学习借鉴使用,本站对版权不负任何法律责任。如果侵犯了您的隐私权益,请联系我们删除。



 
© 2014-2019 ITdaan.com 粤ICP备14056181号  

赞助商广告