{`

const express = require('express');

const jwt = require('jsonwebtoken');

const app = express();

const secret = 'your_secret_key'; // 用于签名的密钥

// 模拟用户数据库

const users = [

{ id: 1, username: 'alice', password: 'password' },

{ id: 2, username: 'bob', password: 'password' }

];

// 登录接口

app.post('/login', (req, res) => {

const user = users.find(u => u.username === req.body.username && u.password === req.body.password);

if (user) {

const token = jwt.sign({ id: user.id }, secret, { expiresIn: '1h' });

res.json({ success: true, token: token });

} else {

res.status(400).json({ success: false, message: 'Invalid credentials' });

}

});

// 需要身份验证的接口

app.get('/protected', (req, res) => {

try {

const decoded = jwt.verify(req.headers.authorization.split(' ')[1], secret);

res.json({ message: 'Welcome!', user: decoded });

} catch (err) {

res.status(401).json({ message: 'Unauthorized' });

}

});

app.listen(3000, () => console.log('Server running on port 3000'));

`}