第三节，接上面的二节，这里我们加入socket.io的处理
首先，我们在./bin/www文件里加入

var routes = require('../routes/index');

var server = http.createServer(app);
//在server下加入socket.io的方法
/**
 * Create WebSocket server
 */
var io = require('socket.io').listen(server);
io.sockets.on('connection', routes.vote);

这里我们加入了socket的监听，并把socket的监听交给routes.vote来处理，在route/index.js中加入

router.vote = function(socket){
    socket.on('send:vote', function(data){
        var ip = socket.handshake.headers['x-forwarded-for'] || socket.handshake.address;
        //查找当前投票
        Poll.findById(data.poll_id, function(error, poll){
            var choice = poll.choices.id(data.choice);
            choice.votes.push({ip: ip});
            poll.save(function(error, doc){
                var theDoc = {
                    question: doc.question, 
                    _id: doc._id, 
                    choices: doc.choices,
                    userVoted: false, 
                    totalVotes: 0
                };
                //查询当前IP是否已经投过票
                poll.choices.forEach(function(choice, index) {
                    choice.votes.forEach(function(vote, index) {
                        theDoc.totalVotes++;
                        theDoc.ip = ip;
                        if(vote.ip === ip){
                            theDoc.userVoted = true;
                            theDoc.userChoice = { _id: choice._id, text: choice.text };
                        }
                    });
                });

                socket.emit('myvote', theDoc);
                socket.broadcast.emit('vote', theDoc);
            });
        });
    });
};

好了，服务端的处理完成了。
在public/js/services/services.js中加入

//webSocket定义
.factory('socket', function($rootScope){
    var socket = io.connect();
    return {
        on: function(eventName, callback){
            socket.on(eventName, function(){
                var args = arguments;
                $rootScope.$apply(function(){
                    callback.apply(socket, args);
                });
            });
        },
        emit: function(eventName, data, callback){
            socket.emit(eventName, data, function(){
                var args = arguments;
                $rootScope.$apply(function(){
                    if(callback){
                        callback.apply(socket, args);
                    }
                });
            });
        }
    }
});

public/js/controllers/controllers.js中加入

//投票详情
.controller('PollItemCtrl', function($scope, $routeParams, socket, Poll){
    Poll.get($routeParams.pollId).then(function(data){
        $scope.poll = data;
    })
    //监听当前用户
    socket.on('myvote', function(data){
        console.dir(data);
        if(data._id === $routeParams.pollId){
            $scope.poll = data;
        }
    });
    //监听投票后的数据
    socket.on('vote', function(data){
        console.dir(data);
        if(data._id === $routeParams.pollId){
            $scope.poll.choices = data.choices;
            $scope.poll.totalVotes = data.totalVotes;
        }
    });
    //投票
    $scope.vote = function(){
        var pollId = $scope.poll._id,
            choiceId = $scope.poll.userVote;
        if(choiceId){
            var voteObj = {
                poll_id : pollId,
                choice: choiceId
            }
            socket.emit('send:vote', voteObj);
        }else{
            alert('请选择一个选项');
        }
    };
})

这里是客户端的处理，以上就是全部代码了
工程地址已经上传到GitHub上了
可以通过以下地址查看或下载
代码查看