首先還是先感謝github,感謝github上提供此段源碼的作者。跟昨晚的來比今天的靜態檔案伺服器有點點複雜些,可以學到很多新的東西。
仔細會發現這次的程式碼多了一個fs.stat函數和ReadStream物件的pipe函數,stat這個函數是用來取得檔案資訊。第一個參數是傳入檔案路徑,第二個則是回呼函數,回呼函數的第二個參數stats的屬性為檔案的基本資訊。 pipe函數用來將這個可讀流和destination目標可寫流連接起來,傳入這個流中的資料將會寫入到destination流中。透過在必要時暫停和恢復流,來源流和目的流得以保持同步。
這個靜態檔案伺服器的改進點在於使用了Last-Modified和If-Modified-Since封包頭,可以不必要地給予瀏覽器傳回它已經存在的檔案。順便可以根據瀏覽器請求資源的壓縮方式傳回給資源進行gzip或deflate壓縮。
var PORT = 8000; var http = require("http"); var url = require("url"); var fs = require("fs"); var path = require("path"); var mime = require("./mime").types; var config = require("./config"); var zlib = require("zlib"); var server = http.createServer(function(request, response) { response.setHeader("Server", "Node/V5"); var pathname = url.parse(request.url).pathname; console.log("url = " + pathname); if (pathname.slice(-1) === "/") { pathname = pathname + config.Welcome.file; } var realPath = __dirname + "/" + path.join("assets", path.normalize(pathname.replace(/\.\./g, ""))); console.log("realPath = " + realPath); var pathHandle = function (realPath) { fs.stat(realPath, function (err, stats) { if (err) { response.writeHead(404, "Not Found", {'Content-Type': 'text/plain'}); response.write("stats = " + stats); response.write("This request URL " + pathname + " was not found on this server."); response.end(); } else { if (stats.isDirectory()) { realPath = path.join(realPath, "/", config.Welcome.file); pathHandle(realPath); } else { var ext = path.extname(realPath); ext = ext ? ext.slice(1) : 'unknown'; var contentType = mime[ext] || "text/plain"; response.setHeader("Content-Type", contentType); //获得文件的修改时间 var lastModified = stats.mtime.toUTCString(); var ifModifiedSince = "If-Modified-Since".toLowerCase(); //设置Last-Modified //服务器给浏览器返回文件最后一次修改时间Last-Modified response.setHeader("Last-Modified", lastModified); if (ext.match(config.Expires.fileMatch)) { var expires = new Date(); expires.setTime(expires.getTime() + config.Expires.maxAge * 1000); response.setHeader("Expires", expires.toUTCString()); response.setHeader("Cache-Control", "max-age=" + config.Expires.maxAge); } //服务器接收浏览器发送过来的If-Modified-Since报文头 //日期相同表示该资源没有变化则返回304 //告诉浏览器该资源你已经有了,不需要再请求了 if (request.headers[ifModifiedSince] && lastModified == request.headers[ifModifiedSince]) { response.writeHead(304, "Not Modified"); response.end(); } else { var raw = fs.createReadStream(realPath); var acceptEncoding = request.headers['accept-encoding'] || ""; var matched = ext.match(config.Compress.match); if (matched && acceptEncoding.match(/\bgzip\b/)) { response.writeHead(200, "Ok", {'Content-Encoding': 'gzip'}); raw.pipe(zlib.createGzip()).pipe(response); } else if (matched && acceptEncoding.match(/\bdeflate\b/)) { response.writeHead(200, "Ok", {'Content-Encoding': 'deflate'}); raw.pipe(zlib.createDeflate()).pipe(response); } else { response.writeHead(200, "Ok"); raw.pipe(response); } } } } }); }; pathHandle(realPath); }); server.listen(PORT); console.log("Server runing at port: " + PORT + ".");
Expires欄位宣告了一個網頁或URL位址不再被瀏覽器快取的時間,一旦超過了這個時間,瀏覽器都應該聯絡原始伺服器。這裡設定失效時間為1年。
exports.Expires = { fileMatch: /^(gif|png|jpg|js|css)$/ig, maxAge: 60*60*24*365 }; exports.Compress = { match: /css|js|html/ig }; exports.Welcome = { file: "index.html" };
枚舉各種資源的類型,可依副檔名設定Content-Type。
exports.types = { "css": "text/css", "gif": "image/gif", "html": "text/html", "ico": "image/x-icon", "jpeg": "image/jpeg", "jpg": "image/jpeg", "js": "text/javascript", "json": "application/json", "pdf": "application/pdf", "png": "image/png", "svg": "image/svg+xml", "swf": "application/x-shockwave-flash", "tiff": "image/tiff", "txt": "text/plain", "wav": "audio/x-wav", "wma": "audio/x-ms-wma", "wmv": "video/x-ms-wmv", "xml": "text/xml" };