@Controller
public class HelloController{
 @RequestMapping("/hello")
 String hello() {
 return "Hello World"; 
 }
}

@app.route("/hello")
def hello():
 return "Hello World"

router.get('/hello', async ctx => {
 ctx.body = 'Hello World'
})

@Controller
class Hello{

}

// 等同于

Controller(Hello)

// Decorator不传参
function Controller(target) {

}

// Decorator传参
function Controller(params) {
 return function (target) {

 }
}

@Controller()
class Hello{

}

var Koa = require('koa');
var Router = require('koa-router');

var app = new Koa();
var router = new Router();

router.get('/', async (ctx, next) => {
 // ctx.router available
});

app
 .use(router.routes())
 .use(router.allowedMethods());

@Controller({prefix: '/hello'})
class HelloController{
 @Request({url: '/', method: RequestMethod.GET})
 async hello(ctx) {
 ctx.body = 'Hello World'
 }
}

function Request({url, method}) {
 return function (target, name, descriptor) {
 let fn = descriptor.value
 descriptor.value = (router) => {
  router[method](url, async(ctx, next) => {
  await fn(ctx, next)
  })
 }
 }
}

const RequestMethod = {
 GET: 'get',
 POST: 'post',
 PUT: 'put',
 DELETE: 'delete'
}

import KoaRouter from 'koa-router'

function Controller({prefix}) {
 let router = new KoaRouter()
 if (prefix) {
 router.prefix(prefix)
 }
 return function (target) {
 let reqList = Object.getOwnPropertyDescriptors(target.prototype)
 for (let v in reqList) {
  // 排除类的构造方法
  if (v !== 'constructor') {
  let fn = reqList[v].value
  fn(router)
  }
 }
 return router
 }
}

import {Controller, Request, RequestMethod} from './decorator'

@Controller({prefix: '/hello'})
export default class HelloController{
 @Request({url: '/', method: RequestMethod.GET})
 async hello(ctx) {
 ctx.body = 'Hello World'
 }
}