//api.js const Koa = require('koa');const router = require('koa-router')();  //路由const bodyParser = require('koa-bodyparser'); //解析原始request请求const fs  = require('fs');  //文件读取const cors = require('koa2-cors'); //设置cors头const app = new Koa;/** * 数据库连接 */var mongoose = require('mongoose');mongoose.connect('mongodb://localhost:27017/admin', {'useNewUrlParser': true});var db = mongoose.connection;db.on('error', console.error.bind(console, 'connection error:'));db.once('open', function() {    console.log('数据库连接成功')    /**      * Schema 用来定义存储在document 中的属性，并且赋予他们校验的规则，和默认值    */    var kittySchema = new mongoose.Schema({        name: String      });      kittySchema.methods.speak = function () {        var greeting = this.name          ? "Meow name is " + this.name          : "I don't have a name";        console.log(greeting);      }      /**         * 定义模型        */      var Kitten = mongoose.model('Kitten', kittySchema);      /**         * 模型实例        */      var silence = new Kitten({ name: 'Silence' });      console.log(silence.name); // 'Silence'      silence.save();  //插库      var fluffy = new Kitten({ name: 'fluffy' });      fluffy.save(function (err, fluffy) {        if (err) return console.error(err);        fluffy.speak();      });});app.use(bodyParser()); app.use(cors({    origin: function (ctx) {        return '*';     }}));let files = fs.readdirSync(__dirname + '/controllers');let js_files = files.filter((f)=>{    return f.endsWith('.js');});for( let f of js_files ){    console.log(`process conteoller : ${f} ...`);    let mapping  = require(__dirname + '/controllers/' + f );        for ( let url in mapping ){        if( url.startsWith('GET ')){            //如果url类似'GET xxx'            let path = url.substring(4);            router.get(path,mapping[url]);        }else if( url.startsWith('POST ') ){            //如果url类似'POST xxx'            let path = url.substring(5);            console.log('请求方式是:',path);            router.post(path,mapping[url]);        }    }}app.use(router.routes());app.listen(8888);console.log('app started at port 8888...');