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node使用Koa2搭建web項(xiàng)目的方法

 更新時(shí)間：2017年10月17日 14:18:45   作者：愛(ài)清清  
本篇文章主要介紹了node使用Koa2搭建web項(xiàng)目的方法，小編覺(jué)得挺不錯(cuò)的，現(xiàn)在分享給大家，也給大家做個(gè)參考。一起跟隨小編過(guò)來(lái)看看吧

隨著Node.js的日益火熱，各種框架開(kāi)始層出不窮的涌現(xiàn)出來(lái)，Node.js也開(kāi)始逐漸的被應(yīng)用到處理服務(wù)端請(qǐng)求的場(chǎng)景中。搭建Web項(xiàng)目的框架也隨之開(kāi)始出現(xiàn)——express、koa、koa2、egg等，當(dāng)然要了解其好壞還是要自己去啃源碼的。本文將不會(huì)涉及到源碼，只是帶領(lǐng)初學(xué)者簡(jiǎn)單了解下Koa2的基本使用，歡迎大家在評(píng)論中互相交流學(xué)習(xí)。

注意：koa2使用了ES7的語(yǔ)法，所以使用時(shí)請(qǐng)升級(jí)Node版本到最新。了解更詳細(xì)的源碼信息可以到git上的koajs/koa去了解

1. 項(xiàng)目目錄結(jié)構(gòu)

2. 代碼邏輯解析

2.1. 包結(jié)構(gòu)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. 啟動(dòng)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);

如果請(qǐng)求的報(bào)文體是XML格式，可以添加下面的代碼自動(dòng)解析報(bào)文（注意引用koa-xxx的版本要與koa2對(duì)應(yīng)）

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數(shù)據(jù)請(qǐng)求單獨(dú)解析存儲(chǔ)
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);

從代碼看到引入了一個(gè)router2controller.js的文件，這個(gè)文件是完成前端請(qǐng)求到具體處理方法的路由過(guò)程

2.3. 路由器文件

[router2controller.js]

該類(lèi)將會(huì)自動(dòng)掃描controller文件夾中的文件來(lái)加載請(qǐng)求映射，不需要挨個(gè)請(qǐng)求單獨(dú)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
 });

自動(dòng)掃描controller包實(shí)現(xiàn)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是用來(lái)處理具體請(qǐng)求信息以及返回?cái)?shù)據(jù)的，userController.js中處理了GET請(qǐng)求獲取用戶(hù)信息，POST請(qǐng)求保存用戶(hù)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:&nbsp;' + userInfo + '</div>'
    + '</body></html>';
  ctx.response.type ='text/html';
  ctx.response.body = html;
};

var saveUserinfo = (ctx, next) => {
  const requestString = ctx.data;
  //TODO數(shù)據(jù)處理
  Console.log(requestString);
};

module.exports = {
  'GET /getUserinfo': getUserinfo,
  'POST /saveUserinfo': saveUserinfo
};

2.5. 數(shù)據(jù)處理

[userService.js]

處理封裝從***Dao.js獲取到的數(shù)據(jù)返回給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 + '&nbsp;|';
    reaponseContent += '年齡：' + user.age + '&nbsp;|';
    reaponseContent += '身高：' + user.height + '<br />';
  }
  return responseContent;
}

module.exports = {
  getUserById : getUserById
};

2.6. 數(shù)據(jù)獲取

[userDao.js]

通過(guò)請(qǐng)求傳入?yún)?shù)來(lái)獲取user數(shù)據(jù)

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. 數(shù)據(jù)庫(kù)操作

[mysqlUtil.js]

包含了數(shù)據(jù)庫(kù)連接池控制，連接建立、釋放管理，執(zhí)行Dao發(fā)起的數(shù)據(jù)庫(kù)操作請(qǐng)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?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持腳本之家。

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