Koa2模拟后端服务实现接口响应

描述

1、Koa需要 node v7.6.0或更高版本来支持ES2015、异步方法。

2、koa搭建后端服务，模拟请求接口。

3、使用第三方路由koa-router

npm install koa-router --save

4、对于post请求，获取请求体使用第三方插件koa-body获取

npm install koa-body --save

步骤

1、新建文件夹：study-koa

2、新建package.json文件，内容如下：

{
  "name": "koa2",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "start": "node index.js"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "koa": "^2.13.4",
    "koa-router": "^10.1.1",
    "supervisor": "^0.12.0"
  }
}

3、新建index.js，内容如下：

const koa = require('koa');
const Router = require('koa-router');
const app = new koa();
const port = process.env.PORT || 4444;
const router = new Router();

// get请求
router.get('/test-entry', async (ctx) => {
    console.log('ctx===', ctx);
    ctx.body = "uuuuuuuu==测试入口"
})
// post请求
router.post('/open', async (ctx) => {
    console.log('ctx===', ctx);
    ctx.body = "open==post请求"
})

app.use(router.routes())
app.listen(port, () => {
    console.log('server listen =' + port);
})
app.on('error', err => {
    log.error('server error', err)
});

4、运行

npm start

5、浏览器运行

http://localhost:4444/test-entry

6、运行结果

uuuuuuuu==测试入口

7、抽取接口文件，分模块载入。新建module文件夹，在此文件夹中新建统一出口文件entry.js，内容如下：

const Router = require('koa-router');
const router = new Router();

router.get('/test-entry', async (ctx) => {
    console.log('ctx===', ctx); // =》打印语句结果展示
    ctx.body = "uuuuuuuu==测试入口"
})

module.exports = router

8、在index.js中加载模块文件。接着执行第4，5步即可得到第6步的结果。

const koa = require('koa');
const Router = require('koa-router');
const app = new koa();
const port = process.env.PORT || 4444;
const router = require(./module/entry.js); // 模块文件

app.use(router.routes())
app.listen(port, () => {
    console.log('server listen =' + port);
})
app.on('error', err => {
    log.error('server error', err)
});

9、获取请求参数之Get请求，通过ctx.request.query获取参数内容。

router.get('/getDetail', async (ctx) => {
		let day = ctx.request.query.day
    if(day === null) {
    	ctx.body = "获取全部信息"
    } else {
    	ctx.body = "获取第"+day+"天的信息"
    } 
})
http://localhost:4444/getDetail?day=1 // 获取第一天的信息
http://localhost:4444/getDetail?day=null // 获取全部信息

10、获取请求参数之Post请求，通过ctx.request.body获取参数内容。

router.post('/login', async (ctx) => {
		let dto = ctx.request.body
    if(dto.name === 'admin' && dto.pass === '123456') {
    	ctx.body = {
    		code: 200,
    		message: '登录成功',
    		data: {
    			username: 'admin',
    			loginTime: '2022-08-03 12:00:22'
    		}
    	}
    } else {
    	ctx.body = {
    		code: 400,
    		message: '登录失败',
    		data: {}
    	}
    } 
})

11、重定向

router.get('/toBaidu', async (ctx) => {
		ctx.redirect('http://www.baidu.com');
})

12、接口造值

router.post('/queryData', async (ctx) => {
		let array = []
		for (let index = 0; index < 10; index++) {
      let obj = {
      id: '(Math.floor(Math.random() * (1000 - 20)) + 1),
      account: (Math.floor(Math.random() * (Math.pow(10, 8) - 20)) + 1),
      name: '爱新觉罗'+index
      }
      array.push(obj);
    }
		ctx.body = {
      code: 200,
      message: 'ok',
      data: array
    }
})

13、路径带参请求并获取

router.get("/api/get/:id?", async (ctx) => {
    console.log(ctx.params.id);  // 2
    ctx.response.body = "获取地址栏携带参数"
})
http://localhost:4444/api/get/id=2

14、跨域请求

npm install koa-cors

//index.js
const cors = require('koa-cors')
app.use(cors());

打印语句结果展示

ctx==={
  request: {
    method: 'GET',
    url: '/test-entry2',
    header: {
      host: 'localhost:4444',
      connection: 'keep-alive',
      'upgrade-insecure-requests': '1',
      'user-agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36',
      accept: 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8',
      'accept-encoding': 'gzip, deflate, br',
      'accept-language': 'zh-CN,zh;q=0.9',
      cookie: 'ZX9mpgzTN2kG9nNK9o=meoyefamhh2vhmn4c2u3ensq; User_Info_Key=%7B%22UserID%22%3A%22abao%22%2C%22UserName%22%3A%22abao%22%2C%22DisplayName%22%3A%22baoge%22%7D; Curve_View_Reminder=1'
    }
  },
  response: {
    status: 404,
    message: 'Not Found',
    header: [Object: null prototype] {}
  },
  app: { subdomainOffset: 2, proxy: false, env: 'development' },
  originalUrl: '/test-entry2',
  req: '<original node req>',
  res: '<original node res>',
  socket: '<original node socket>'
}