会话与无状态令牌
了解何时 JWT 比 Cookie 更适合 API
会话与无状态令牌 是 CoddyKit 上的免费 Flask Academy 课时。 这是第 1 节课，共 4 节。 你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。 这是 Flask Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Flask Academy 课程共包含 4 节课。
本课时的部分内容尚未翻译，以英文显示。
Two Ways to Remember Users
HTTP forgets you between requests. To keep someone logged in, you either store a session on the server or hand the client a signed token.
How Sessions Work
With a session, the server keeps your login state and gives the browser a tiny cookie holding only a session id. Every request, the server looks that id up. 🍪
The Cost of Sessions
Because the server stores the state, it must remember every active user. That server-side state gets heavy and tricky to share across many machines.
How Tokens Flip It
A token carries the user info itself, signed by the server. The server no longer stores anything; it just verifies the signature on each request.
What Stateless Means
Stateless means the server holds no memory of the client. Everything it needs to trust you travels inside the token on each call.
Meet the JWT
A JWT (JSON Web Token) is the standard stateless token. It is a compact, signed string that any server with the key can verify instantly.
Three Parts of a JWT
A JWT has three dot-separated parts: a header, a payload, and a signature. The header names the algorithm used to sign it.
header.payload.signatureClaims Live in the Payload
The middle part holds claims: small facts like the user id or an expiry time. It is encoded, not encrypted, so never put secrets there.
{ "sub": "42", "exp": 1699999999 }Signature Builds Trust
The signature is made from the header, payload, and a secret only the server knows. Change one byte and verification fails.
When Tokens Win
Tokens shine for APIs and mobile clients that scale across many servers, since no shared session store is needed to verify a caller.
When Sessions Still Fit
For a classic server-rendered website, sessions are simpler and easy to revoke. The right pick depends on your app, not on hype.
Quick Check
Think about what makes a token approach stateless.
Recap
Sessions store state on the server; JWTs push signed state to the client. Tokens stay stateless, making them a great fit for scalable APIs. 🚀
常见问题解答
「会话与无状态令牌」课时是免费的吗？
是的 — 「会话与无状态令牌」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Flask Academy 课程的其余内容，请升级到 CoddyKit PRO。 Flask Academy 课程共包含 4 节课。
「会话与无状态令牌」这节课中我会学到什么？
了解何时 JWT 比 Cookie 更适合 API 你通过在浏览器中直接运行的动手代码来练习 Flask Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。
学习 Flask Academy 需要有经验吗？
无需任何先前经验。CoddyKit 上的 Flask Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。 这是第 1 节课，共 4 节。
「会话与无状态令牌」课时需要多长时间？
大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。
我能在这节 Flask Academy 课中编写并运行代码吗？
能。每节 Flask Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。