1.创建最基本的中间件 const express = require('express');const send = require('send');const app = express()const mw = function (re
const express = require('express');const send = require('send');const app = express()const mw = function (req, res, next) { console.log('middleware'); // 一定要调用next() 把流转关系交给下一个中间件或路由 next()}app.listen(80, () => { console.log('express server running at ');})
客户端发起的任何请求,到达服务器之后,都会触发的中间件
const express = require('express');const send = require('send');const app = express()const mw = (req, res, next) => { console.log('middleware'); // 一定要调用next() 把流转关系交给下一个中间件或路由 next()}// 将mw注册为全局生效的中间件app.use(mw)app.get('/', (req, res) => { res.send('Home Page')})app.get('/user', (req, res) => { res.send('User Page')})app.listen(80, () => { console.log('express server running at ');})
const express = require('express');const send = require('send');const app = express()const mw1 = (req, res, next) => { console.log('mw1'); next()}// 局部生效app.get('/', mw1, (req, res) => { res.send('Home Page')})app.get('/user', (req, res) => { res.send('User Page')})app.listen(80, () => { console.log('express server running at ');})
多个局部生效的中间件
const express = require('express');const send = require('send');const app = express()const mw1 = (req, res, next) => { console.log('mw1'); next()}const mw2 = (req, res, next) => { console.log('mw2'); next()}// 局部生效// app.get('/', [mw1,mw2], (req, res) => { 也行app.get('/', mw1,mw2, (req, res) => { res.send('Home Page')})app.get('/user', (req, res) => { res.send('User Page')})app.listen(80, () => { console.log('express server running at ');})
中间件必须在路由之前注册
错误级别中间件必须在所有路由之后
举例:express.JSON()
const express = require('express');const send = require('send');const app = express()// 配置解析表单数据的中间件app.use(express.json())app.get('/', (req, res) => { console.log(req.header, req.body); res.send('User Page')})app.listen(80, () => { console.log('express server running at ');})
来源地址:https://blog.csdn.net/weixin_63681863/article/details/131982910
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