1
const Koa=require('koa');
const mysql =require('promise-mysql');
const server=new Koa();
server.use(async (ctx, next)=>{ //koa只能用use,没有get,post方法，而是要用koa-router
//use只有一个参数，那就中间件函数
let db = await mysql.createPool({
host:'localhost',
user:'root',
password:'123456',
database:'computer'
})
let data=await db.query('update user_table set name=? where id=?',['dream1','2'])
ctx.body=data
});
server.listen(3000)
const Koa=require('koa')
const fs=require('promise-fs')
const server=new Koa()
server.use(async (ctx,next)=>{
const txt=await fs.readFile("./1.txt")
ctx.txt=txt.toString()
await next()
})
server.use(async (ctx,next)=>{
await fs.appendFile('./log.txt',`[${new Date().toGMTString()}] ${ctx.method} ${ctx.url}\n`)
await next()
})
server.use((ctx,next)=>{
ctx.body=ctx.txt
})
server.listen(3000)
- koa-better-body 和ctx.redirect()重定向的使用
const Koa=require('koa')
const Router=require('koa-router')
const fs=require('promise-fs')
const bodyParser=require('koa-better-body')
const server=new Koa()
const router=new Router();
let login=false;
server.use(bodyParser())
server.use(async (ctx,next)=>{
await next()
})
server.use(router.routes())
router.get('/',(ctx,next)=>{
console.log(111)
if(!login){
console.log(222)
ctx.redirect('/login')
}
console.log(444)
ctx.body="欢迎"
})
router.get('/login',async (ctx,next)=>{
const data=await fs.readFile('./static/login.html')
ctx.body=data.toString()
})
router.post('/login',(ctx,next)=>{
console.log(123)
console.log(ctx.request.fields)
login=true
ctx.redirect('/')
})
server.listen(3000)
- koa下载文件，自定义文件名称
const Koa=require('koa')
const Router=require('koa-router')
const fs=require('promise-fs')
const server=new Koa();
const router=new Router()
router.get('/download', async (ctx,next)=>{
ctx.attachment("ltf.txt")
const data=await fs.readFile('./static/login.html')
ctx.body=data
})
server.use(router.routes())
server.listen(3000)
4.下载的文件由程序动态指定内容就要用内存流
const Koa=require('koa');
const Router=require('koa-router');
const fs=require('promise-fs');
const MemoryStream=require('memorystream');
let server=new Koa();
server.listen(8080);
let router=new Router();
router.get('/b', async ctx=>{
let stream=new MemoryStream();
ctx.attachment('20170813.txt');
ctx.body=stream;
stream.write('aaa');
stream.write('bbb');
stream.end();
});
server.use(router.routes());
5 操作http的头信息
const Koa=require('koa');
const Router=require('koa-router');
const fs=require('promise-fs');
const MemoryStream=require('memorystream');
let server=new Koa();
server.listen(8080);
let router=new Router();
router.get('/', async ctx=>{
//console.log(ctx.headers);
//console.log(ctx.headers['host']);
//console.log(ctx.get('host'));
ctx.set('name', 'blue');
ctx.set('age', '18');
ctx.set('set-cookie', 'type=12');
ctx.body='welcome';
});
server.use(router.routes());
6.下载大文件的时候返回流给body就行
const Koa=require('koa');
const Router=require('koa-router');
const fs=require('promise-fs');
const MemoryStream=require('memorystream');
let server=new Koa();
server.listen(8080);
let router=new Router();
router.get('/', async ctx=>{
ctx.attachment('aaa.txt');
// ctx.body=await fs.readFile('static/1.txt');
ctx.body=await fs.createReadStream('static/1.txt');
});
server.use(router.routes());
7 koa向第三方网站请求数据
const Koa=require('koa');
const request=require('./libs/request');
let server=new Koa();
server.listen(8080);
// http://ip.taobao.com/service/getIpInfo.php?ip=[ip地址字串]
server.use(async ctx=>{
let url=`http://ip.taobao.com/service/getIpInfo.php?ip=202.13.96.75`;
try{
let data=await request(url);
let json=JSON.parse(data.toString());
ctx.body=json;
}catch(e){
ctx.body='地址解析失败';
}
});
//request.js文件
const http=require('http');
module.exports=function (url){
return new Promise((resolve, reject)=>{
let req=http.request(url, res=>{
let arr=[];
res.on('data', data=>{
arr.push(data);
});
res.on('end', ()=>{
let buffer=Buffer.concat(arr);
resolve(buffer);
});
});
req.end();
req.on('error', err=>{
reject(err);
});
});
};
- koa-static静态资源访问，设置缓存有效时间，
const Koa=require('koa')
const static=require('koa-static')
const Router=require('koa-router')
let server=new Koa();
server.listen(8080);
let router=new Router()
router.all(/\.(jpg|png|gif)$/i,static('./static',{
maxage:60*86400*1000
}))
router.all(/\.js$/i,static('./static',{
maxage:1*86400*1000
}))
router.all(/\.css$/i,static('./static',{
maxage:7*86400*1000
}))
router.all(/\.html?$/i,static('./static',{
maxage:1*86400*1000
}))
router.all('*',static('./static',{
maxage:7*86400*1000
}))
server.use(router.routes())
/*
server.use(static('./static',{
maxage:60*86400*1000,
index:'index.html',//当别人访问/的时候
}))
*/
- koa图片上传封装
const Koa = require('koa')
const Router = require('koa-router')
const static = require('koa-static')
const fs = require('promise-fs')
const upload = require('./lib/upload')
const path=require('path')
const server = new Koa()
const router = new Router()
router.post('/upload', ...upload({
async success(ctx) {
ctx.body = { e: 'suc' }
}, async failed (err) {
if (err == 'maxfilesize exceeded') {
ctx.status = 406 //可以覆盖upload.js里面的
ctx.body = { e: 'error', msg: '文件过大' }
}else{
ctx.body={e:"error",msg:"服务器错误"}
}
},
path:path.resolve(__dirname,'upload'),
maxFileSize:100*1024
}))
server.use(router.routes())
server.use(static('./static', {
maxage: 7 * 3600 * 24 * 1000,
index: 'form.html'
}))
server.listen(8080)
// lib/upload.js
const convert=require('koa-convert')
const body=require('koa-better-body')
module.exports=function(options){
return [async(ctx,next)=>{
try{
await next()
}catch(e){
if(e.message.startsWith('maxFileSize exceeded')){
ctx.status=406
options.failed &&await options.failed(ctx,'maxfilesize exceeded')
}
else{
ctx.status=500
ctx.body={e:"error",msg:"服务器错误"}
options.failed && await options.failed(ctx,'server error')
}
}
},convert(body({
uploadDir:options.path,
maxFileSize:options.maxFileSize
})),async (ctx,next)=>{
console.log(ctx.request)
options.success&&await options.success(ctx)
}]
}
