如何用Python做登录系统

要用Python做一个登录系统，你需要使用用户验证、密码存储、数据库管理和安全措施等技术。 首先，选择一个适当的数据库管理系统，如SQLite、MySQL或PostgreSQL。其次，使用Python的库如Flask或Django来创建Web应用程序。最后，确保用户密码的安全存储和验证，通过使用哈希算法和盐值来增加安全性。

下面是详细描述如何使用Flask和SQLite来创建一个简单的登录系统：

一、安装和设置环境

首先，确保你安装了Python和pip。然后安装Flask和SQLite库：

pip install Flask pip install Flask-SQLAlchemy pip install Flask-Bcrypt

二、项目结构

创建一个项目目录，并在其中创建以下文件：

/login_system app.py models.py forms.py templates/ login.html register.html

三、设置数据库模型

在models.py中，定义用户模型：

from flask_sqlalchemy import SQLAlchemy
from flask import Flask
app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///site.db'
db = SQLAlchemy(app)
class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(20), unique=True, nullable=False)
    emAIl = db.Column(db.String(120), unique=True, nullable=False)
    password = db.Column(db.String(60), nullable=False)
    def __repr__(self):
        return f"User('{self.username}', '{self.email}')"

四、创建表单

在forms.py中，定义注册和登录表单：

from flask_wtf import FlaskForm
from wtforms import StringField, PasswordField, SubmitField, BooleanField
from wtforms.validators import DataRequired, Length, Email, EqualTo
class RegistrationForm(FlaskForm):
    username = StringField('Username', validators=[DataRequired(), Length(min=2, max=20)])
    email = StringField('Email', validators=[DataRequired(), Email()])
    password = PasswordField('Password', validators=[DataRequired()])
    confirm_password = PasswordField('Confirm Password', validators=[DataRequired(), EqualTo('password')])
    submit = SubmitField('Sign Up')
class LoginForm(FlaskForm):
    email = StringField('Email', validators=[DataRequired(), Email()])
    password = PasswordField('Password', validators=[DataRequired()])
    remember = BooleanField('Remember Me')
    submit = SubmitField('Login')

五、创建路由和视图函数

在app.py中，配置Flask应用程序和创建路由：

from flask import Flask, render_template, url_for, flash, redirect
from forms import RegistrationForm, LoginForm
from models import db, User
from flask_bcrypt import Bcrypt
app = Flask(__name__)
app.config['SECRET_KEY'] = 'your_secret_key'
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///site.db'
db.init_app(app)
bcrypt = Bcrypt(app)
@app.route("/register", methods=['GET', 'POST'])
def register():
    form = RegistrationForm()
    if form.validate_on_submit():
        hashed_password = bcrypt.generate_password_hash(form.password.data).decode('utf-8')
        user = User(username=form.username.data, email=form.email.data, password=hashed_password)
        db.session.add(user)
        db.session.commit()
        flash('Your account has been created!', 'success')
        return redirect(url_for('login'))
    return render_template('register.html', title='Register', form=form)
@app.route("/login", methods=['GET', 'POST'])
def login():
    form = LoginForm()
    if form.validate_on_submit():
        user = User.query.filter_by(email=form.email.data).first()
        if user and bcrypt.check_password_hash(user.password, form.password.data):
            flash('You have been logged in!', 'success')
            return redirect(url_for('home'))
        else:
            flash('Login Unsuccessful. Please check email and password', 'danger')
    return render_template('login.html', title='Login', form=form)
@app.route("/home")
def home():
    return "Home Page"
if __name__ == '__main__':
    app.run(debug=True)

六、模板

在templates文件夹中，创建register.html和login.html文件：

register.html:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Register</title>
</head>
<body>
    <form method="POST" action="">
        {{ form.hidden_tag() }}
        <div>
            {{ form.username.label }} {{ form.username }}
        </div>
        <div>
            {{ form.email.label }} {{ form.email }}
        </div>
        <div>
            {{ form.password.label }} {{ form.password }}
        </div>
        <div>
            {{ form.confirm_password.label }} {{ form.confirm_password }}
        </div>
        <div>
            {{ form.submit }}
        </div>
    </form>
</body>
</html>

login.html:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Login</title>
</head>
<body>
    <form method="POST" action="">
        {{ form.hidden_tag() }}
        <div>
            {{ form.email.label }} {{ form.email }}
        </div>
        <div>
            {{ form.password.label }} {{ form.password }}
        </div>
        <div>
            {{ form.remember.label }} {{ form.remember }}
        </div>
        <div>
            {{ form.submit }}
        </div>
    </form>
</body>
</html>