var http=require("http"),

fs=require('fs');

var server=http.createServer(function(req,res){

    if("GET"==req.method && "/images"==req.url.substr(0,7) && ".jpg"==req.url.substr(-4)){

        fs.stat(__dirname+req.url,function(err,stat){//检测文件是否存在

            if(err||!stat.isFile()){

                res.writeHead(404);

                res.end('NOT FOUND');

                return;

            }

            serve(__dirname+req.url,"application/jpg");

        });

    }else if('GET'==req.method && '/'==req.url){

        serve(__dirname+'/index.html','text/html');

    }else{

        res.writeHead(404);

        res.end("NOT FOUND");

    }

    function serve(path,type){

        res.writeHead(200,{"Content-Type":"type"});

        fs.createReadStream(path).pipe(res);//将文件系统流接到http响应流中

    }

});

server.listen(3000);