代码：

var http = require('http');

var url = require('url');
var fs = require('fs');  //涉及文件读取
http.createServer(function (req, res, next) {
    var pathname = url.parse(req.url).pathname;

    ///结尾的请求，自动添加上”index.html
    if (pathname.slice(-1) === "/") {
        pathname = pathname + 'index.html';
    }

    var path = __dirname + pathname;
    var exists = fs.existsSync(path)
    if (exists) {
        var stat = fs.statSync(path);
        if (stat.isFile()) {
            fs.readFile(path, function (err, data) {
                res.write(data);
                res.end();
            });
        } else {
            //不是文件一律输出403
            res.writeHead(403);
            res.end('403 This path cannot be accessed')
        }
    } else {

        res.writeHead(404);
        res.end('404 not found.')
    }

}).listen(3000, function () {
    console.log('listen http://localhost:3000')
});