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[Java教程]Node.js静态文件服务器


首先还是先感谢github,感谢github上提供此段源码的作者。跟昨晚看的静态文件服务器来比今天的静态文件服务器稍微复杂些,可以学到很多新的东西。
仔细会发现这次的代码多了一个fs.stat函数和ReadStream对象的pipe函数,stat这个函数是用来获取文件信息。第一个参数是传入文件路径,第二个则是回调函数,回调函数的第二个参数stats的属性为文件的基本信息。pipe函数用于将这个可读流和destination目标可写流连接起来,传入这个流中的数据将会写入到destination流中。通过在必要时暂停和恢复流,来源流和目的流得以保持同步。

该静态文件服务器的改进点在于使用了Last-Modified和If-Modified-Since报文头,可以不必要给浏览器返回它已经存在的文件。顺便可以根据浏览器请求资源的压缩方式返回给资源进行gzip或者deflate压缩。

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字段声明了一个网页或URL地址不再被浏览器缓存的时间,一旦超过了这个时间,浏览器都应该联系原始服务器。这里设置失效时间为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"};


枚举各种资源的类型,可根据扩展名设置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+, "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", "};