求高手指点，node index.js 可以正常启动，显示正在监听端口，但是不能访问localhost:3000 。 一个简单的小项目，利用smoothie.js对数据实时可视化。
直接贴代码： index.js
var express=require('express');
var app=express();
var http=require('http').Server(app);
var io=require('socket.io')(http);
var dgram = require('dgram');
var server = dgram.createSocket('udp4');
app.get('/',function(req,res){
res.sendFile(__dirname+'/index.html');
});
server.on('message', function(msg, rinfo) {
console.log('服务端获取信息：'+msg+'来自：'+rinfo.address+':'+rinfo.port);
io.sockets.emit('data',msg);
});
server.on('listening', function() {
var address = server.address();
console.log('服务端正在监听：'+address.address+':'+address.port);
});
server.bind(7);
index.html
<!doctype html>
<html>
<head>
</head>
<body onload="createTimeline()">
<p>The <em>hello world</em> of <a href="../">Smoothie Charts</a>. View source.</p>
<canvas id="chart" width="400" height="100"></canvas>
<script type="text/javascript" src="smoothie.js"></script>
<script src="https://cdn.socket.io/socket.io-1.2.0.js"></script>
<script type="text/javascript">
var data1 = 0;
var socket = io('http://localhost:3000');
socket.on('data',function(data){
data1 = data;
});
// Randomly add a data point every 500ms
var random = new TimeSeries();
setInterval(function() {
random.append(new Date().getTime(), data1);
}, 500);
function createTimeline() {
var chart = new SmoothieChart();
chart.addTimeSeries(random, { strokeStyle: 'rgba(0, 255, 0, 1)', fillStyle: 'rgba(0, 255, 0, 0.2)', lineWidth: 4 });
chart.streamTo(document.getElementById("chart"), 500);
}
</script>
</body>
</html>