module.exports = (req, res, next) => { if (req.method === "POST" && req.path === "/login") { if (req.body.username === "jack" && req.body.password === "123456") { return res.status(200).json({ user: { token: "123", }, }); } else { return res.status(400).json({ message: "用户名或者密码错误" }); } } next(); };