代码改变世界

WebSocket 学习(三)--用nodejs搭建服务器

2016-04-18 08:19  stoneniqiu  阅读(...)  评论(...编辑  收藏

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