包含功能
登录注册(不开放注册只是用固定的账号信息)
查看列表
查看详情
发布信息
编辑信息
删除信息
项目接口

npm init -y
npm install koa --save
npm istall koa-router --save (旧版本) 或者 npm install @koa/router --save （新版本）
npm install bluebird --save
npm install koa-ejs --save
npm install koa-bodyparser --save

执行完毕之后 ，使用vscode 打开项目文件夹,继续往里面添加对应的文件目录和文件

authenticate.js

//认证中间件
module.exports = async function (ctx,next) {const logined = ctx.cookies.get('logined',{signed: true});ctx.state.logined = !!logined;await next();
}

路由开发
routes/post.js

const Router = require('koa-router');
const postService = require('../services/post');
const router = new Router();//发布表单页面
router.get('/publish', async (ctx) => {await ctx.render('publish');
});//发布处理
router.post('/publish', async (ctx) => {const data = ctx.body;if (!data.title || !data.content) {ctx.throw(500, '缺失必填参数');}const item = postService.publish(data.title, data.content);ctx.redirect(`/post/${item.id}`);
});//详情页面
router.get('/post/:postId', async (ctx) => {const post = postService.show(ctx.params.postId);if (!post) {ctx.throw(404, '消息记录不存在');}await ctx.render('post', { post: post });
});//编辑表单页面
router.get('/update/:postId',async (ctx)=>{const post = postService.show(ctx.params.postId); if (!post) {ctx.throw(404, '消息记录不存在');}await ctx.render('post', { post: post });
});//编辑处理
router.post('/update/:postId',async (ctx)=>{const data = ctx.body;if (!data.title || !data.content) {ctx.throw(500, '缺失必填参数');}const postId = ctx.params.postId;postService.update(postId,data.title,data.content);ctx.redirect(`/post/${postId}`);
});//删除
router.get('delete/:postId',async (ctx)=>{postService.delete(ctx.params.postId);ctx.redirect('/');
});module.exports = router;

routes/site.js

const Router = require('koa-router');
const postService = require('../services/post');
const router = new Router();//网站首页
router.get('/', async (ctx)={const list = postService.list();await ctx.render('index',{list : list});
});module.exports = router;

routes/user.js

const Router = require('koa-router');
const userService = require('../services/user');
const router = new Router();//登陆页面
router.get('/login', async(ctx) = {await ctx.render('login');
});//登录处理
router.post('/login', async(ctx) = {const data = ctx.request.body;if(!data.userName || !data.password){ctx.throw(500, '用户名或密码缺失必填参数');
}
const logined = userService.login(data.userName, data.password);
if (!logined) {ctx.throw(500, '用户名或密码错误');
}
ctx.cookies.set('logined', 1, {signed: true,httpOnly: true
});
ctx.router('/', '登陆成功');
});//退出登录
router.get('/logout', (ctx) => {ctx.cookies.set('logined', 0, {signed: true,maxAge: -1});ctx.router('/', '退出登陆成功');
});```**服务层开发 
services/post.js**
```
const fs = require('fs');
const bluebird = require('bluebird');//Promise 化 fs 的api
bluebird.promisifyAll(fs);//文章数据
const posts = [];
//文章ID
let postId = 1;//发表文章
exports.publish = function(title,content){const item = {id: postId++,title: title,content: content,time: (new Date()).toLocaleDateString()};posts.push(item);return item;
}//查看文章
exports.show = function(id){id = Number(id);for(const post of posts){if(post.id === id){return post;}}return null;
}//编辑文章
exports.update =function(id,title,content){id = Number(id);posts.forEach((post)=>{if(post.id === id){post.title = title;post.content = content;}});
}//删除文章
exports.delete = function (id){id = Number(id);let index = -1;posts.forEach((post)=>{if(post.id === id){index = id;}});if(index > -1){posts.slice(index,1)}
}exports.list = function(){return posts.map(item => item);
}```**serivce/user.js**```
const user = {liuyifei: 'password'
};//登录
exports.login = function(userName,password){if(user[userName] === undefined){return false;}return user[userName]  === password;
};
```=======================================================
**前端模板:**
**index.ejs**
```
<h1>文章显示列表</h1>
<% if(list.length === 0){ %>
<p>文章显示列表</p>
<% }else{ %>
<table><tr><th>id</th><th>标题</th><th>发布时间</th><% if(logined){ %><th>操作</th><% } %>  </tr><% list.forEach(post => { %><td><%= post.id %></td> <td><a href="/post/<%= post.id %>"><%= post.title  %></a></td> <td><%= post.time %></td> <% if(logined){ %><th><a href="/update/<%= post.id %>">编辑</a></th><th><a href="/delete/<%= post.id %>" onclick="return confirm('确认删除?')">删除</a></th><% } %><% }) %>
</table>
<% } %>    
```**login.ejs**
```
<form action="/login" method="post" enctype="application/x-www-form-urlencoded"><fieldset><legend>登录</legend><div><label for="userName">账号</label><input type="text" name="userName" id="userName" required /></div><div><label for="userName">密码</label><input type="password" name="password" id="password" required /></div>  <div><button type="submit">登录</button></div>    </fieldset>
</form>
```
**main.ejs**
```
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta http-equiv="X-UA-Compatible" content="ie=edge"><title>首页</title>
</head><body><% if(logined) { %><a href="/">首页</a><a href="/publish">发表文章</a><a href="/logout">退出登录</a><% }else{%><a href="/login">退出登录</a><% } %><%- body  %></body>
</html>
```
**post.ejs**
```
<div><h1><%= post.title  %></h1> <time>发布时间:<%= post.time %></time>
<hr><div><%= post.content  %></div>
</div>
```
**publish.ejs**```
<form action="/publish" method="post" enctype="application/x-www-form-urlencoded"><fieldset><legend>发表文章</legend><div><label for="title">标题</label><input type="text" name="title" id="title" required></div><div><label for="content">内容</label><textarea name="content" id="content" required></textarea></div><div><button type="submit">发布</button><button type="reset">重置</button></div></fieldset>
</form>
```****update.ejs****
```
<form action="/update/<%=post.id  %>" method="post" enctype="application/x-www-form-urlencoded"><fieldset><legend>编辑文章</legend><div><label for="title">标题</label><input type="text" name="title" id="title" value="<%= post.title  %>" required></div><div><label for="content">内容</label><textarea name="content" id="content"  required ><%= post.content  %></textarea></div><div><button type="submit">发布</button><button type="reset">重置</button></div></fieldset></fieldset>
</form>
```
**index.js : 项目的入口文件,负责挂载中间件，路由，应用配置以及启动服务器**```
const Koa = require('koa');
const render = reuire('koa-ejs');
const bodyParser = require('koa-bodyParser');
//认证组件
const authenticate = require('./middlewares/authenticate');//路由
const siteRoute = require('./routes/site');
const userRoute = require('./routes/user');
const postRoute = require('./routes/post');const app = new Koa(); //定义服务
app.keys = ['wusoddn09Wa']；  //定义认证使用的key//挂载中间件
app.use(bodyParser());//关联使用模版
render(app,{root: './templates',layout: 'main',viewExt: 'ejs'}
);//挂载路由
app.use(siteRoute.routes()).use(siteRoute.allowedMethods());
app.use(userRoute.routes()).use(userRoute.allowedMethods());
app.use(postRoute.routes()).use(postRoute.allowedMethods());app.listen(8080,()=>{console.log(server start up on port: 8080);
});```