flask 登录注册带有状态保持用CBV写

下面是使用 Flask CBV（Class-Based Views）编写的带有状态保持的登录和注册功能的示例代码：

from flask import Flask, render_template, request, redirect, url_for, session
from flask.views import View

app = Flask(__name__)
app.secret_key = 'your_secret_key_here'

# 用户数据库
users = []

class RegisterView(View):
    methods = ['GET', 'POST']

    def dispatch_request(self):
        if request.method == 'POST':
            username = request.form['username']
            password = request.form['password']

            # 检查用户名是否已存在
            for user in users:
                if user['username'] == username:
                    return 'Username already exists!'

            # 创建新用户
            user = {'username': username, 'password': password}
            users.append(user)
            session['username'] = username

            return redirect(url_for('profile'))

        return render_template('register.html')


class LoginView(View):
    methods = ['GET', 'POST']

    def dispatch_request(self):
        if request.method == 'POST':
            username = request.form['username']
            password = request.form['password']

            # 验证用户名和密码
            for user in users:
                if user['username'] == username and user['password'] == password:
                    session['username'] = username
                    return redirect(url_for('profile'))

            return 'Invalid username or password!'

        return render_template('login.html')


class ProfileView(View):
    methods = ['GET']

    def dispatch_request(self):
        if 'username' in session:
            return f"Welcome, {session['username']}!"
        else:
            return redirect(url_for('login'))


class LogoutView(View):
    methods = ['GET']

    def dispatch_request(self):
        session.clear()
        return redirect(url_for('login'))


app.add_url_rule('/register', view_func=RegisterView.as_view('register'))
app.add_url_rule('/login', view_func=LoginView.as_view('login'))
app.add_url_rule('/profile', view_func=ProfileView.as_view('profile'))
app.add_url_rule('/logout', view_func=LogoutView.as_view('logout'))


if __name__ == '__main__':
    app.run()

在上述代码中，我们使用了 Flask 的 CBV 功能，通过继承 `View` 类来创建视图类。每个视图类都有一个 `dispatch_request` 方法，用于处理不同的 HTTP 请求。

`RegisterView` 处理用户注册，`LoginView` 处理用户登录，`ProfileView` 显示用户个人资料，`LogoutView` 注销用户。在注册和登录过程中，我们将用户名存储在会话中以实现状态保持。

通过以上示例代码，您可以使用 Flask 的 CBV 来实现带有状态保持的登录和注册功能。