记一些浏览器缓存以前不太熟悉的东西

var http = require("http");
var fs   = require("fs");
var url  = require("url");
var querystring = require("querystring");

http.createServer(function(req,res){
    var gurl = req.url,
        pathname = url.parse(gurl).pathname;

    if( pathname.indexOf("favicon.ico")>=0){
        var ico = fs.readFileSync("./favicon.ico");
        res.writeHead(200,{
            "Content-Type" : "image/x-icon"
        })
        res.end(ico);
        return;
    }

    if(pathname.indexOf("/static/")==0){
        var realPath = __dirname + pathname;
        dealWithStatic(pathname,realPath,res,req);
        return;
    }
}).listen(5555);

function dealWithStatic(pathname,realPath,res,req){
    fs.exists(realPath,function(exists){
        if(!exists){
            res.writeHead(404,{
                "Content-Type" : "text/html"
            });
            res.end("not find!!!");
        }else{
            var mmieString = /\.([a-z]+$)/i.exec(pathname)[1],
                cacheTime  = 2*60*60,
                mmieType;
            switch(mmieString){
                case "html" :
                case "htm"  :
                case "xml"  : mmieType = "text/html";
                break;
                case "css"  : mmieType = "text/css";
                break;
                case "js"   : mmieType = "text/plain";
                break;
                case "png"  : mmiType  = "image/png";
                break;
                case "jpg"  : mmiType  = "image/jpeg";
                break;                
                default     : mmieType = "text/plain";
            }

            var fileInfo      = fs.statSync(realPath),
                lastModied    = fileInfo.mtime.toUTCString(),
                modifiedSince = req.headers[‘if-modified-since‘]

            if(modifiedSince && lastModied == modifiedSince){
                res.writeHead(304,"Not Modified");
                res.end();
                return;
            }

            fs.readFile(realPath,function(err,file){
                if(err){
                    res.writeHead(500,{
                        "Content-Type" : "text/plain"
                    });
                    res.end(err);
                }else{
                    var d = new Date();
                    var expires = new Date(d.getTime()+10*60*1000);
                    res.writeHead(200,{
                        "Content-Type"  : mmieType,
                        "Expires"       : expires.toUTCString(),
                        "Cache-Control" : "max-age=" + cacheTime,
                        "Last-Modified" : lastModied
                    });
                    res.end(file);
                }
            });
        }
    });
}