静态资源文件管理(配置静态文件环境，这样就可一直接引入css以及图片)

/*
* 这是fs模块
* */
var http = require("http");
var url = require("url");
var fs = require("fs");
var path = require("path");
http.createServer(function(req,res){
    //得到用户的路径
    var pathname = url.parse(req.url).pathname;
    //默认首页
    if(pathname == "/"){
        pathname = "1.html";
    }
    //拓展名
    var extname = path.extname(pathname);
    //真的读取这个文件
    fs.readFile("./static/"+pathname,function(err,data){
        if(err){
            //如果此页面不存在返回404
            console.log(1);
            fs.readFile("./static/404.html",function(err,data){
                res.writeHead(404,{"Content-type":"text/html;charset=UTF-8"});
                res.end(data);
            });
            return;
        }
        var mime = getMime(extname);
        res.writeHead(200,{"Content-type":mime});
        res.end(data);
    });

}).listen(3000,"127.0.0.1");

function getMime(extname){
    switch (extname){
        case ".html":
            return "text/html";
            break;
        case ".jpg":
            return "image/jpg";
            break;
        case ".png":
            return "image/png";
            break;
        case ".css":
            return "text/css";
            break;
    }
}