express简单实现

express 框架实现

const http = require("http");
const url = require("url");
 
function createApp() {var app = {};
  var routes = [];
 
  // 将所有请求方式写入 app 对象中
  http.METHODS.forEach(method => {method = method.toLocaleLowerCase();
    app[method] = (path, handler) => {
      let route = {
        path,
        method,
        handler
      };
      routes.push(route);
    };
  });
 
  // 匹配剩余路由
  app.all = (path, handler) => {
    let route = {
      method: "all",
      path,
      handler
    };
    routes.push(route);
  };
 
  // 中间件
  app.use = (path, handler) => {if(handler === undefined) {
      handler = path;
      path = "/";
    }
 
    let route = {
      method: "middle",
      path,
      handler,
    }
 
    routes.push(route);
  }
 
  // 服务
  let server = http.createServer((req, res) => {let method = req.method.toLocaleLowerCase();
    let {pathname} = url.parse(req.url, true);
    pathname = decodeURI(pathname);
    // 循环路由，匹配到就执行它的 handler 函数
    // 用 next 函数
    let i = 0;
 
    let next = () => {if(i >= routes.length) return;
      let {method: m, path: p, handler: h} = routes[i];
      i++;
      if(m === 'middle') {
        // 匹配中间件
        if(p == '/' || p == pathname || pathname.startsWith(p+'/')) {h(req, res, next);
        } else {next();
        }
      } else {
        // 匹配一般路由
        if ((m == method || m == "all") && (p == pathname || p === "*")) {h(req, res);
        } else {next();
        }
      }
    }
 
    next();});
 
  app.listen = (...rest) => {server.listen(...rest);
  };
 
  return app;
}
 
module.exports = createApp;

静态资源服务中间价实现

const path = require("path");
const fs = require("fs");
const url = require('url');
 
const mime = {
  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",
  unknown: "text/plain"
};
 
function static(basename) {return (req, res, next) => {let { pathname} = url.parse(req.url, true);
        pathname = decodeURI(pathname);
        let p = path.resolve(path.join(basename, pathname));
        fs.stat(p, (err, stats) => {if(err) next();
            if(stats && stats.isFile()) {let ext = path.extname(p).slice(1);
                res.writeHead(200, {"content-type": `${mime[ext]};charset=utf-8`})
                let rs = fs.createReadStream(p);
                rs.pipe(res);
            } else {next();
            }
        })
    }
}
 
module.exports = static;

使用

const createApp =  require('./app/index');
const static =  require('./app/static');
 
let app = createApp();
 
app.use(static('./static'));
 
app.all('*', (req, res) => {res.end('404');
});
 
app.listen(8080, '127.0.0.1');