知新 | koa框架入门到熟练第二章

koa-bodyparser 使用

这里对koa-bodyparser的使用教程。

目录如下

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ejs文件

ejs模板文件

    
    



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koa-bodyparser

使用koa-bodyparser获取body内容

var koa = require("koa");

var Router = require("koa-router");

var bodyParser = require("koa-bodyparser");

var app = new koa();

var router = new Router();

var views = require("koa-views");

app.use(views("views", {
    extension: "ejs",
}))

app.use(bodyParser());

// koa中间件
app.use(async (ctx, next) => {
    console.log(new Date());

    await next();
});



router.get("/", async (ctx) => {
    await ctx.render("index");
})

router.post("/doAdd", async (ctx) => {
    console.log(ctx.request.body);
    ctx.body = ctx.request.body;
})
app.use(router.routes());
app.use(router.allowedMethods());


app.listen(3001);

使用效果

登录页面

koa-static

这里学习使用koa-static

安装

PS C:\Users\Administrator\Desktop\untitled3> npm install --save koa-static
npm WARN [email protected] No description
npm WARN [email protected] No repository field.

+ [email protected]
added 1 package in 2.042s

2 packages are looking for funding
  run `npm fund` for details

PS C:\Users\Administrator\Desktop\untitled3>

访问效果

访问效果如下
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art-template

这里使用art-template 作为一个模板引擎使用

安装

PS C:\Users\Administrator\Desktop\untitled3> npm install --save art-template
npm WARN [email protected] No description
npm WARN [email protected] No repository field.

+ [email protected]
added 33 packages from 141 contributors in 6.704s

2 packages are looking for funding
  run `npm fund` for details

PS C:\Users\Administrator\Desktop\untitled3> npm install --save koa-art-template
npm WARN [email protected] No description
npm WARN [email protected] No repository field.

+ [email protected]
added 2 packages from 4 contributors in 2.336s

2 packages are looking for funding
  run `npm fund` for details

代码如下

var koa = require("koa");

var Router = require("koa-router");

var bodyParser = require("koa-bodyparser");

var static = require("koa-static");

var app = new koa();

var router = new Router();

var views = require("koa-views");

var render = require("koa-art-template");

var path = require("path");

app.use(views("views", {
    extension: "ejs",
}))

app.use(static("./static"));

app.use(bodyParser());

// koa中间件
app.use(async (ctx, next) => {
    console.log(new Date());

    await next();
});



router.get("/", async (ctx) => {
    await ctx.render("index");
})

router.post("/doAdd", async (ctx) => {
    console.log(ctx.request.body);
    ctx.body = ctx.request.body;
})

render(app, {
    root: path.join(__dirname, "views"),
    extname: ".art",
})

app.use(async function (ctx){
    await ctx.render("user");
})

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


app.listen(3001);

art 文件如下

var koa = require("koa");

var Router = require("koa-router");

var bodyParser = require("koa-bodyparser");

var static = require("koa-static");

var app = new koa();

var router = new Router();

var views = require("koa-views");

var render = require("koa-art-template");

var path = require("path");

app.use(views("views", {
    extension: "ejs",
}))

app.use(static("./static"));

app.use(bodyParser());

// koa中间件
app.use(async (ctx, next) => {
    console.log(new Date());

    await next();
});



router.get("/", async (ctx) => {
    await ctx.render("index");
})

router.post("/doAdd", async (ctx) => {
    console.log(ctx.request.body);
    ctx.body = ctx.request.body;
})

render(app, {
    root: path.join(__dirname, "views"),
    extname: ".art",
})

app.use(async function (ctx){
    await ctx.render("user");
})

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


app.listen(3001);

访问效果

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cookie

var koa = require("koa");

var Router = require("koa-router");

var bodyParser = require("koa-bodyparser");

var static = require("koa-static");

var app = new koa();

var router = new Router();

var views = require("koa-views");

var render = require("koa-art-template");

var path = require("path");


app.use(bodyParser());

// koa中间件
app.use(async (ctx, next) => {
    console.log(new Date());

    await next();
});

router.get("/", async (ctx) => {
    ctx.cookies.set("ming", "ming")
})
app.use(router.routes());
app.use(router.allowedMethods());


app.listen(3001);

koa-session

PS C:\Users\Administrator\Desktop\untitled3> npm install koa-session
npm WARN [email protected] No description
npm WARN [email protected] No repository field.

+ [email protected]
added 10 packages from 14 contributors in 3.484s

2 packages are looking for funding
  run `npm fund` for details

PS C:\Users\Administrator\Desktop\untitled3>

编写一个简单的刷新页面次数增加

var koa = require("koa");

var Router = require("koa-router");

var bodyParser = require("koa-bodyparser");

var static = require("koa-static");

var app = new koa();

var router = new Router();

var views = require("koa-views");

var render = require("koa-art-template");

var path = require("path");

var session = require("koa-session");

app.keys = ['secret'];   // session加密字段

app.use(session({
    key: 'koa:sess', //cookie key (default is koa:sess)
    maxAge: 86400000, // cookie的过期时间 maxAge in ms (default is 1 days)
    overwrite: true, //是否可以overwrite    (默认default true)
    httpOnly: true, //cookie是否只有服务器端可以访问 httpOnly or not (default true)
    signed: true, //签名默认true
    rolling: false, //在每次请求时强行设置cookie，这将重置cookie过期时间（默认：false）
    renew: false, //(boolean) renew session when session is nearly expired,
}, app));

app.use(bodyParser());

// koa中间件
app.use(async (ctx, next) => {
    console.log(new Date());

    await next();
});


app.use(ctx => {
    // ignore favicon
    if (ctx.path === '/favicon.ico') return
    console.log(ctx.session)
    let n = ctx.session.views || 0
    ctx.session.views = ++n
    ctx.body = n + ' views'
});


router.get("/", async (ctx) => {
    ctx.cookies.set("ming", "ming")
})

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


app.listen(3001);

原型链继承

// 构造原型
function Person(name, age) {
    this.name = name;
    this.age = 333;
    this.run = function () {
        console.log(this.name, this.age)
    }
}

// 添加work方法，在原型链上继承
Person.prototype.work = () => {
    console.log("work");
}

function Web() {

}

// 同样继承
Web.prototype = new Person();

var w = new Web();
// 以下两个运行原型链的值
w.run();
w.work()

静态方法和构造方法

// 新建类
class Person{
    constructor(name) {
        this._name = name;
    }
    run(){
        console.log(this._name);
    }
    // 静态方法
    static work(){
        console.log("静态方法");
    }
}

Person.work();

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koa 操作mongoDB

安装相关的库

PS C:\Users\Administrator\Desktop\untitled3> npm install mongodb --save
npm WARN [email protected] No description
npm WARN [email protected] No repository field.

+ [email protected]
updated 1 package in 2.854s

2 packages are looking for funding
  run `npm fund` for details

PS C:\Users\Administrator\Desktop\untitled3>

增加一条数据

var MongoClient = require("mongodb").MongoClient;

var dbUrl = 'mongodb://106.53.115.12:27017/'

var dbName = "koa";

// 连接
MongoClient.connect(dbUrl, (err, client) => {
    if(err){
        console.log(err);
        return;
    }

    var db = client.db(dbName);

    // 增加数据
    db.collection("user").insertOne({
        "username":"xiaoxiao","age":"23"
    });

})

结果：

对返回结果进行处理

var MongoClient = require("mongodb").MongoClient;

var dbUrl = 'mongodb://106.53.115.12:27017/'

var dbName = "koa";

// 连接
MongoClient.connect(dbUrl, (err, client) => {
    if(err){
        console.log(err);
        return;
    }

    var db = client.db(dbName);

    // 增加数据
    db.collection("user").insertOne({
        "username":"xiaoxiao","age":"23"
    }, function (err, result) {
        if(!err){
            console.log("增加数据成功 ");
            client.close();
            console.timeEnd("start");
        }
    });

})

查询数据

代码如下

var MongoClient = require("mongodb").MongoClient;

var dbUrl = 'mongodb://106.53.115.12:27017/'

var dbName = "koa";

// 连接
MongoClient.connect(dbUrl, (err, client) => {
    if(err){
        console.log(err);
        return;
    }

    var db = client.db(dbName);

    var result = db.collection("user").find(0);

    result.toArray((err, docs) => {
        console.log(docs);
    })

})

输出内容如下

"C:\Program Files\nodejs\node.exe" C:\Users\Administrator\Desktop\untitled3\01es6.js
(node:15216) DeprecationWarning: current Server Discovery and Monitoring engine is deprecated, and will be removed in a future version. To use the new Server Discover and Monitoring engine, pass option { useUnifiedTopology: true } to the MongoClient constructor.
[
  { _id: 5f0fe666bc0d9e41101dffd3, username: 'xiaoxiao', age: '23' },
  { _id: 5f0fe7f4949f1b420c120fe7, username: 'xiaoxiao', age: '23' }
]

koa 应用生成器

全局安装

使用全局安装koa的脚手架

PS C:\Users\Administrator\Desktop\untitled3> npm install koa-generator -g
npm WARN deprecated [email protected]: Legacy versions of mkdirp are no longer supported. Please update to mkdirp 1.x. (Note that the API surface has changed to use Promises in 1.x.)
C:\Users\Administrator\AppData\Roaming\npm\koa -> C:\Users\Administrator\AppData\Roaming\npm\node_modules\koa-generator\bin\koa
C:\Users\Administrator\AppData\Roaming\npm\koa2 -> C:\Users\Administrator\AppData\Roaming\npm\node_modules\koa-generator\bin\koa2
+ [email protected]
updated 1 package in 0.905s
PS C:\Users\Administrator\Desktop\untitled3>

创建项目

PS C:\Users\Administrator\Desktop> ls


    目录: C:\Users\Administrator\Desktop


Mode                LastWriteTime         Length Name
----                -------------         ------ ----
d-----        2020/7/14     17:08                insurv-mina-node-api
d-----        2020/7/14     17:45                koa
d-----        2020/7/14     17:55                untitled
d-----        2020/7/16     14:16                untitled3
-a----        2020/7/16     12:04        5782870 Navicat Premium 15.x最新注册机.zip
-a----        2020/7/14     17:07           1428 Visual Studio Code.lnk
-a----       2019/11/30     18:03           1526 WPS 2019.lnk
-a----        2020/7/14     18:52           1064 百度网盘.lnk


PS C:\Users\Administrator\Desktop> mkdir ./ming


    目录: C:\Users\Administrator\Desktop


Mode                LastWriteTime         Length Name
----                -------------         ------ ----
d-----        2020/7/16     14:19                ming


PS C:\Users\Administrator\Desktop> ls


    目录: C:\Users\Administrator\Desktop


Mode                LastWriteTime         Length Name
----                -------------         ------ ----
d-----        2020/7/14     17:08                insurv-mina-node-api
d-----        2020/7/14     17:45                koa
d-----        2020/7/16     14:19                ming
d-----        2020/7/14     17:55                untitled
d-----        2020/7/16     14:16                untitled3
-a----        2020/7/16     12:04        5782870 Navicat Premium 15.x最新注册机.zip
-a----        2020/7/14     17:07           1428 Visual Studio Code.lnk
-a----       2019/11/30     18:03           1526 WPS 2019.lnk
-a----        2020/7/14     18:52           1064 百度网盘.lnk


PS C:\Users\Administrator\Desktop> cd ./ming
PS C:\Users\Administrator\Desktop\ming> ls
PS C:\Users\Administrator\Desktop\ming> koa koa_demo

   create : koa_demo
   create : koa_demo/package.json
   create : koa_demo/app.js
   create : koa_demo/public
   create : koa_demo/routes
   create : koa_demo/routes/index.js
   create : koa_demo/routes/users.js
   create : koa_demo/public/javascripts
   create : koa_demo/views
   create : koa_demo/views/index.jade
   create : koa_demo/views/layout.jade
   create : koa_demo/views/error.jade
   create : koa_demo/public/images
   create : koa_demo/public/stylesheets
   create : koa_demo/public/stylesheets/style.css
   create : koa_demo/bin
   create : koa_demo/bin/www

   install dependencies:
     > cd koa_demo && npm install

   run the app:
     > SET DEBUG=koa_demo:* & npm start

PS C:\Users\Administrator\Desktop\ming> ls


    目录: C:\Users\Administrator\Desktop\ming


Mode                LastWriteTime         Length Name
----                -------------         ------ ----
d-----        2020/7/16     14:19                koa_demo


PS C:\Users\Administrator\Desktop\ming> cd ./koa_demo
PS C:\Users\Administrator\Desktop\ming\koa_demo>

此时脚手架已经安装成功

安装依赖

PS C:\Users\Administrator\Desktop\ming\koa_demo> npm install
npm WARN deprecated [email protected]: Chokidar 2 will break on node v14+. Upgrade to chokidar 3 with 15x less dependencies.
npm WARN deprecated [email protected]: This package is no longer maintained
npm WARN deprecated [email protected]: Jade has been renamed to pug, please install the latest version of pug instead of jade
npm WARN deprecated [email protected]: Please update to at least constantinople 3.1.1
npm WARN deprecated [email protected]: Deprecated, use jstransformer
npm WARN deprecated [email protected]: 'native-or-bluebird' is deprecated. Please use 'any-promise' instead.

> [email protected] postinstall C:\Users\Administrator\Desktop\ming\koa_demo\node_modules\nodemon
> node bin/postinstall || exit 0

npm notice created a lockfile as package-lock.json. You should commit this file.
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: [email protected] (node_modules\fsevents):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for [email protected]: wanted {"os":"darwin","arch":"any"} (current: {"os":"win32","arch":"x64"})

added 367 packages from 208 contributors in 21.748s

1 package is looking for funding
  run `npm fund` for details

PS C:\Users\Administrator\Desktop\ming\koa_demo>

启动项目

npm start