[JavaScript知识库]node.js连接数据库写接口

//初始化
npm init
//安装依赖
npm install body-parser express mysql cors -S 

引入路由，把页面拆分开：

connect.js

const mysql = require('mysql')
const express = require('express')
const app = express()
const router = express.Router();

// 解析参数
const bodyParser = require('body-parser')
let login = true;
// json请求
app.use(bodyParser.json())
// 表单请求
app.use(bodyParser.urlencoded({extended: false}))

const option = {
    host: 'localhost',
    user: 'root',
    password: 'root',
    port: '3306',
    database: 'yyds',//表名
    connectTimeout: 5000, //连接超时
    multipleStatements: false //是否允许一个query中包含多条sql语句
}
let pool;
repool()
function Result ({ code = 1, msg = '', data = {} }) {
    this.code = code;
    this.msg = msg;
    this.data = data;
}
// 断线重连机制
function repool() {
    // 创建连接池
    pool = mysql.createPool({
        ...option,
        waitForConnections: true, //当无连接池可用时，等待（true）还是抛错（false）
        connectionLimit: 100, //连接数限制
        queueLimit: 0 //最大连接等待数（0为不限制）
    })
    pool.on('error', err => {
        err.code === 'PROTOCOL_CONNECTION_LOST' && setTimeout(repool, 2000)
    })
    app.all('*', (_,__, next) => {
        pool.getConnection( err => {
            err && setTimeout(repool, 2000) || next()
        })
    })
}

module.exports = { app, pool, Result, router }

router/login.js

const { pool, router, Result } = require('../connect')

router.get('/', (req, res) => {
    pool.getConnection((err, conn) => {
        conn.query("SELECT * FROM t_user", (e, r) => {
            if(e) throw error
            res.json(new Result({ data: r }))
        })
        pool.releaseConnection(conn) // 释放连接池，等待别的连接使用
    })
})

module.exports = router;

入口文件 index.js

const { app, pool, Result } =require('./connect')
const login = require('./router/login')
app.all('*', (req, res, next) => {
    //这里处理全局拦截，一定要写在最上面
    next()
})
app.all('/', (req, res) => {
    pool.getConnection((err, conn) => {
        res.json({ type: 'test'})
        pool.releaseConnection(conn) // 释放连接池，等待别的连接使用
    })
})
app.use('/login', login)
app.listen(8088, () => {
    console.log('服务启动')
})