June 2021
Intermediate to advanced
290 pages
9h 21m
Chinese
Content preview from Node与Express开发（第2版）
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94
｜
第
9
章
9.4.1
内存存储
如果你更愿意把
Session
信息存储到服务器上（这也是我推荐的），就需要一个存储它的地
方。入门级的选择就是内存存储。内存存储的
Session
很容易建立起来
，但有一个很大的
不足：只要重启服务器（在学习本书的过程中你会重启很多次的！），
Session
信息就会消
失。甚至还有更糟的，如果你的服务横向扩展到多台服务器上（参见第
12
章）
，每次请求
都可能由不同的服务器来提供服务，那么结果是
Session
数据有时候存在
，有时候却不存
在。这显然是用户不能接受的使用体验。不过就开发和测试来说，内存存储的
Session
已
经可以满足需要了。在第
13
章将看到如何持久化
Session
的存储信息。
首先，安装
express-session
（
npm install express-session
）。然后，在链入
Cookie
解析
器后链入
express-session
（版本库的
ch09/meadowalrk.js
）：
const expressSession = require('express-session')
// 要确保在链入Session中间件之前链入了Cookie中间件！
app.use(expressSession({
resave: false,
saveUninitialized: false,
secret: credentials.cookieSecret,
}))
express-session
中间件接收一个配置对象，这个配置对象包含以下选项。
resave ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.