### 使用 Python Flask 框架连接 MySQL 数据库实现登录和注册功能 #### 创建项目结构 为了更好地组织代码，建议按照如下目录结构来构建应用： ``` /flask_app /templates login.html register.html app.py config.py ``` #### 安装依赖包 确保安装必要的Python包以便能够顺利运行应用程序。 ```bash pip install flask pymysql sqlalchemy flask_sqlalchemy flask_login wtforms ``` #### 配置数据库连接 在`config.py`中定义数据库连接字符串和其他配置项。 ```python import os basedir = os.path.abspath(os.path.dirname(__file__)) class Config(object): SECRET_KEY = 'you-will-never-guess' SQLALCHEMY_DATABASE_URI = 'mysql+pymysql://username:password@localhost:3306/dbname' # 替换成自己的数据库信息[^2] SQLALCHEMY_TRACK_MODIFICATIONS = False ``` #### 初始化Flask应用并设置蓝图 编辑`app.py`, 导入所需的模块，并初始化Flask实例以及相关扩展组件。 ```python from flask import Flask, render_template, redirect, url_for, flash from forms import LoginForm, RegistrationForm from models import db, User from flask_login import LoginManager, login_user, logout_user, current_user, login_required def create_app(): application = Flask(__name__) application.config.from_object('config.Config') db.init_app(application) login_manager = LoginManager() login_manager.login_view = "login" login_manager.init_app(application) @login_manager.user_loader def load_user(user_id): return User.query.get(int(user_id)) from views import main as main_blueprint application.register_blueprint(main_blueprint) with application.app_context(): db.create_all() return application ``` #### 设计模型类 创建名为`models.py`的新文件，在其中定义表示用户的ORM映射关系。 ```python from datetime import datetime from werkzeug.security import generate_password_hash, check_password_hash from flask_login import UserMixin from extensions import db class User(UserMixin, db.Model): __tablename__ = 'users' id = db.Column(db.Integer(), primary_key=True) username = db.Column(db.String(80), unique=True, nullable=False) email = db.Column(db.String(120), unique=True, nullable=False) password_hash = db.Column(db.String(128)) created_at = db.Column(db.DateTime, default=datetime.utcnow) def set_password(self, password): self.password_hash = generate_password_hash(password) def verify_password(self, password): return check_password_hash(self.password_hash, password) ``` #### 构建视图函数与路由逻辑 编写处理HTTP请求的具体业务流程。新建一个叫做`views.py`的文件用于放置这些方法。 ```python from flask import Blueprint, request, jsonify from forms import LoginForm, RegistrationForm from models import User from flask_login import login_user, logout_user, login_required main = Blueprint('main', __name__) @main.route('/register', methods=['GET', 'POST']) def register(): form = RegistrationForm(request.form) if form.validate_on_submit(): user = User(username=form.username.data, email=form.email.data) user.set_password(form.password.data) try: db.session.add(user) db.session.commit() flash('恭喜你，注册成功!', category='success') return redirect(url_for('.login')) except Exception as e: db.session.rollback() flash(f'{e}', category='danger') return render_template('register.html', title="Register", form=form) @main.route("/login", methods=["GET", "POST"]) def login(): if current_user.is_authenticated: return redirect(url_for(".index")) form = LoginForm() if form.validate_on_submit(): user = User.query.filter_by(email=form.email.data).first_or_404() if not user or not user.verify_password(form.password.data): flash("Invalid credentials.", "error") return redirect(url_for(".login")) login_user(user, remember=form.remember_me.data) next_page = request.args.get('next') return redirect(next_page) if next_page else redirect(url_for(".index")) return render_template("login.html", title="Sign In", form=form) @main.route("/logout") @login_required def logout(): logout_user() return redirect(url_for(".index")) @main.route("/") def index(): return "<h1>Welcome to the Home Page!</h1>" ``` #### 编写HTML模板 最后一步是在`/templates`下分别建立两个简单的HTML表单——`login.html` 和 `register.html`. 下面仅展示部分代码片段作为示范: ##### login.html ```html {% extends "base.html" %} {% block content %} <h2>Login</h2> <form action="" method="post"> {{ form.hidden_tag() }} <p> {{ form.email.label }}<br> {{ form.email(size=32) }}<br> {% for error in form.email.errors %} <span style="color:red;">[{{ error }}]</span><br> {% endfor %} </p> <!-- 更多字段... --> <button type="submit">Log In</button> </form> <a href="{{url_for('main.register')}}">Don't have an account?</a> {% endblock %} ``` ##### register.html ```html {% extends "base.html" %} {% block content %} <h2>Register</h2> <form action="" method="post"> {{ form.hidden_tag() }} <p> {{ form.username.label }}<br> {{ form.username(size=32) }}<br> {% for error in form.username.errors %} <span style="color:red;">[{{ error }}]</span><br> {% endfor %} </p> <!-- 更多字段... --> <button type="submit">Register</button> </form> <a href="{{url_for('main.login')}}">Already registered? Log in here.</a> {% endblock %} ``` 通过上述步骤可以完成基于Flask框架加MySQL数据库的基础用户认证系统的搭建工作[^4].