1、搭建后台服务

1-1 安装依赖

yarn  add koa koa-router koa2-cors koa-body koa-static
yarn  add mongoose
yarn  add require-directory

1-2 分拆项目

//index.js
const Koa = require("koa");
const app =  new Koa();
const initManage = require("./config");
initManage(app);
app.listen(4000)

// config/index.js
const requireDir = require("require-directory");
const Router = require("koa-router");
const static = require("koa-static");
const body = require("koa-body");
const cors = require("koa2-cors");
function initManage(app){
  app.use(body({
    // 1.解析post请求，及图片上传
    multipart: true,
    formidable: {
      maxFileSize: 200*1024*1024,
          keepExtensions: true
    }
  }));
  //2.跨域
  app.use(cors());
  //3.路由自动导入
  requireDir(module,`${process.cwd()}/routers`,{visit:loadRouter})
  function loadRouter(obj){
    if(obj instanceof Router){
      app.use(obj.routes())
    }
  }
  //4.静态资源
  app.use(static(`${process.cwd()}/images`))
}
module.exports = initManage;

// routers/api/article.js
const router = require("koa-router")();
router.get("/article",async ctx=>{
    ctx.body = "article"
})
module.exports = router;