在Node.js中如何创建Web、TCP服务器

var express = require('express'); 
var app = express(); 
app.get('', function(req, res){ 
<span style="white-space:pre"> </span>res.end('hello\n'); 
<span style="white-space:pre"> </span>}); 
<span style="white-space:pre"> </span>app.listen(18001, function afterListen(){ 
<span style="white-space:pre"> </span>console.log('express running on http://localhost:18001'); 
<span style="white-space:pre"> </span>});

<span style="white-space:pre"></span>app.use(express.static('./public'));

var http = require('http');
var url = require('url');
var path = require('path');
var fs = require('fs');
var dir, arg = process.argv[2] || ''; // 命令行第三个参数，用来接收目录，可为空，相对当前server.js文件的目录名称
// 比如使用命令 node server debug，意思就是debug文件夹与server.js文件同级
// 且你想以debug文件夹启动web服务
 
http.createServer(function (req, res) {
var pathname = __dirname + url.parse(req.url).pathname;
dir = dir ? dir : pathname; // 记住dir(目录)
pathname = dir ? pathname.replace(dir, dir + arg + '/') : pathname; // 替换文件静态路径
if (path.extname(pathname) == "") {
pathname += "/";
}
if (pathname.charAt(pathname.length - 1) == "/") {
pathname += "index.html"; // 入口文件，此处默认index.html
}
 
fs.exists(pathname, function (exists) {
if (exists) {
switch (path.extname(pathname)) {
case ".html":
res.writeHead(200, {"Content-Type": "text/html"});
break;
case ".js":
res.writeHead(200, {"Content-Type": "text/javascript"});
break;
case ".css":
res.writeHead(200, {"Content-Type": "text/css"});
break;
case ".gif":
res.writeHead(200, {"Content-Type": "image/gif"});
break;
case ".jpg":
res.writeHead(200, {"Content-Type": "image/jpeg"});
break;
case ".png":
res.writeHead(200, {"Content-Type": "image/png"});
break;
default:
res.writeHead(200, {"Content-Type": "application/octet-stream"});
} 
// res可以自己添加信息来简单交互 比如可以修改点header信息 或者修改返回的资源数据
fs.readFile(pathname, function (err, data) {
res.end(data);
});
}
else {
res.writeHead(404, {"Content-Type": "text/html"});
res.end("<h1>404 Not Found</h1>");
}
});
}).listen(8085, "127.0.0.5"); // 服务器端口
console.log("server running at http://127.0.0.5:8085/");