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(tài)文件服務(wù)器有點(diǎn)點(diǎn)復(fù)雜些，可以學(xué)到很多新的東西。
仔細(xì)會發(fā)現(xiàn)這次的代碼多了一個fs.stat函數(shù)和ReadStream對象的pipe函數(shù)，stat這個函數(shù)是用來獲取文件信息。第一個參數(shù)是傳入文件路徑，第二個則是回調(diào)函數(shù)，回調(diào)函數(shù)的第二個參數(shù)stats的屬性為文件的基本信息。pipe函數(shù)用于將這個可讀流和destination目標(biāo)可寫流連接起來，傳入這個流中的數(shù)據(jù)將會寫入到destination流中。通過在必要時暫停和恢復(fù)流，來源流和目的流得以保持同步。
該靜態(tài)文件服務(wù)器的改進(jìn)點(diǎn)在于使用了Last-Modified和If-Modified-Since報文頭，可以不必要給瀏覽器返回它已經(jīng)存在的文件。順便可以根據(jù)瀏覽器請求資源的壓縮方式返回給資源進(jìn)行g(shù)zip或者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); //獲得文件的修改時間 var lastModified = stats.mtime.toUTCString(); var ifModifiedSince = "If-Modified-Since".toLowerCase(); //設(shè)置Last-Modified //服務(wù)器給瀏覽器返回文件最后一次修改時間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); } //服務(wù)器接收瀏覽器發(fā)送過來的If-Modified-Since報文頭 //日期相同表示該資源沒有變化則返回304 //告訴瀏覽器該資源你已經(jīng)有了,不需要再請求了 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字段聲明了一個網(wǎng)頁或URL地址不再被瀏覽器緩存的時間，一旦超過了這個時間，瀏覽器都應(yīng)該聯(lián)系原始服務(wù)器。這里設(shè)置失效時間為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，可根據(jù)擴(kuò)展名設(shè)置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"};新聞熱點(diǎn)
疑難解答
