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node使用Koa2搭建web项目的方法

程序员文章站 2022-06-24 17:33:55
随着node.js的日益火热,各种框架开始层出不穷的涌现出来,node.js也开始逐渐的被应用到处理服务端请求的场景中。搭建web项目的框架也随之开始出现——express...

随着node.js的日益火热,各种框架开始层出不穷的涌现出来,node.js也开始逐渐的被应用到处理服务端请求的场景中。搭建web项目的框架也随之开始出现——express、koa、koa2、egg等,当然要了解其好坏还是要自己去啃源码的。本文将不会涉及到源码,只是带领初学者简单了解下koa2的基本使用,欢迎大家在评论中互相交流学习。

注意:koa2使用了es7的语法,所以使用时请升级node版本到最新。了解更详细的源码信息可以到去了解

1. 项目目录结构

node使用Koa2搭建web项目的方法

2. 代码逻辑解析

2.1. 包结构文件

[package.json]

{
 "name": "weixin-node-koa",
 "version": "1.0.0",
 "description": "node.js with koa2",
 "private": true,
 "dependencies": {
  "koa": "^2.0.0",
  "koa-router": "^7.0.0",
  "mysql":"2.13.0"
 },
 "scripts": {
  "start": "node app.js"
 },
 "engines": {
  "node": ">=6.0.0"
 },
 "author": "fly",
 "license": "centerm"
}

2.2. 启动入口文件

[app.js]

const koa = require('koa');
const app = new koa();
const router2controller = require('./app/router2controller.js');
const config = require('./config/config.local.js');

app.use(router2controller());
app.listen(config.port);
console.log("server started and listen on port " + config.port);

如果请求的报文体是xml格式,可以添加下面的代码自动解析报文(注意引用koa-xxx的版本要与koa2对应)

const koa = require('koa');
const app = new koa();
const router2controller = require('./app/router2controller.js');
const config = require('./config/config.local.js');

//start接收到的xml数据请求单独解析存储
const xmlparser = require('koa-xml-body');
app.use(xmlparser()).use((ctx,next) => {
  ctx.data = ctx.request.body;
  return next();
});
//end

app.use(router2controller());
app.listen(config.port);
console.log("server started and listen on port " + config.port);

从代码看到引入了一个router2controller.js的文件,这个文件是完成前端请求到具体处理方法的路由过程

2.3. 路由器文件

[router2controller.js]

该类将会自动扫描controller文件夹中的文件来加载请求映射,不需要挨个请求单独配置

koa-router原生提供方法如下:

router
 .get('/', async (ctx,next) => {
  this.body = 'hello world!';
 })
 .post('/users', async (ctx,next) => {
  //todo
 })
 .put('/users/:id', async (ctx,next) => {
  //todo
 })
 .del('/users/:id', async (ctx,next) => {
  //todo
 });

自动扫描controller包实现方法如下

const fs = require('fs');
const router = require('koa-router')();

function addmapping(router, mapping) {
  for (var url in mapping) {
    if (url.startswith('get ')) {
      var path = url.substring(4);
      router.get(path, mapping[url]);
      console.log(`register url mapping: get ${path}`);
    } else if (url.startswith('post ')) {
      var path = url.substring(5);
      router.post(path, mapping[url]);
      console.log(`register url mapping: post ${path}`);
    } else if (url.startswith('put ')) {
      var path = url.substring(4);
      router.put(path, mapping[url]);
      console.log(`register url mapping: put ${path}`);
    } else if (url.startswith('delete ')) {
      var path = url.substring(7);
      router.del(path, mapping[url]);
      console.log(`register url mapping: delete ${path}`);
    } else {
      console.log(`invalid url: ${url}`);
    }
  }
}

function addcontrollers(router, dir) {
  fs.readdirsync(__dirname + '/' + dir).filter((f) => {
    return f.endswith('.js');
  }).foreach((f) => {
    console.log(`process controller: ${f}...`);
    let mapping = require(__dirname + '/' + dir + '/' + f);
    addmapping(router, mapping);
  });
}

module.exports = function (dir) {
  var controllersdir = dir || 'controller';
  addcontrollers(router, controllersdir);
  return router.routes();
};

2.4. 控制器

[usercontroller.js]

***controller.js是用来处理具体请求信息以及返回数据的,usercontroller.js中处理了get请求获取用户信息,post请求保存用户信息

const userservice = require('./../service/userservice.js');

var getuserinfo = (ctx, next) => {
  let query = ctx.query;
  let userid = query.id;
  let userinfo = userservice.getuserbyid(userid);

  let html = '<html><body>'
    + '<div> userinfo: ' + userinfo + '</div>'
    + '</body></html>';
  ctx.response.type ='text/html';
  ctx.response.body = html;
};

var saveuserinfo = (ctx, next) => {
  const requeststring = ctx.data;
  //todo数据处理
  console.log(requeststring);
};

module.exports = {
  'get /getuserinfo': getuserinfo,
  'post /saveuserinfo': saveuserinfo
};

2.5. 数据处理

[userservice.js]

处理封装从***dao.js获取到的数据返回给controller

const userdao = require('./../dao/userdao.js');

var getuserbyid = async (userid) => {
  var users = userdao.getuserbyid(userid);
  var responsecontent = '';
  for(let user of users) {
    reaponsecontent += '姓名:' + user.name + ' |';
    reaponsecontent += '年龄:' + user.age + ' |';
    reaponsecontent += '身高:' + user.height + '<br />';
  }
  return responsecontent;
}

module.exports = {
  getuserbyid : getuserbyid
};

2.6. 数据获取

[userdao.js]

通过请求传入参数来获取user数据

const mysql = require('./../utils/mysqlutil.js');

var getuserbyid = async (userid) => {
  let mysqloptions = {
    sql : 'select * from table_user where user_id = ?',
    args : [userid]
  };

  var users = await mysql.execquery(mysqloptions);
  if(users.length == 0) {
    return null;
  } else {
    return users;
  }
};

module.exports = {
  getuserbyid : getuserbyid
};

2.7. 数据库操作

[mysqlutil.js]

包含了数据库连接池控制,连接建立、释放管理,执行dao发起的数据库操作请求

const mysql = require('mysql');
const config = require('./../../config/config.local.js');

var connectionpool = mysql.createpool({
  'host' : config.database.host,
  'port':config.database.port,
  'user' : config.database.user,
  'password' : config.database.password,
  'database' : config.database.database,
  'charset': config.database.charset,
  'connectionlimit': config.database.connectionlimit,
  'supportbignumbers': true,
  'bignumberstrings': true
});

var release = connection => {
  connection.end(function(error) {
    if(error) {
      console.log('connection closed failed.');
    } else {
      console.log('connection closed succeeded.');
    }
  });
};

var execquery = sqloptions => {
  var results = new promise((resolve, reject) => {
      connectionpool.getconnection((error,connection) => {
      if(error) {
        console.log("get connection from mysql pool failed !");
        throw error;
      }

      var sql = sqloptions['sql'];
      var args = sqloptions['args'];

      if(!args) {
        var query = connection.query(sql, (error, results) => {
          if(error) {
            console.log('execute query error !');
            throw error;
          }

          resolve(results);
        });
      } else {
        var query = connection.query(sql, args, function(error, results) {
          if(error) {
            console.log('execute query error !');
            throw error;
          }

          resolve(results);
        });
      }

      connection.release(function(error) {
        if(error) {
          console.log('mysql connection close failed !');
          throw error;
        }
      });
    });
  }).then(function (chunk) {
    return chunk;
  });

  return results;
};

module.exports = {
  release : release,
  execquery : execquery
}

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持。