npm install body-parser --save
let bodyParser = require('body-parser');
app.use(bodyParser.json());//解析json
app.use(bodyParser.urlencoded({extended:false}));//解析formData的格式

let querystring = require('querystring');
querystring.parse('name=1&age=2','&','=');
querystring.stringify({name:1,age:2},'&&','=');

npm install cookie-parser --save
let cookieParser = require('cookie-parser');
app.use(cookieParser());
req.cookies //可以直接获取cookie转换后的对象
req.cookie(key,value,{domain,path,expires,maxAge,httpOnly});

npm install express-session --save
let session = require('express-session');