flask+mysql实现用户登录注册代码

以下是一个简单的 Flask+MySQL 实现用户登录注册的代码：

from flask import Flask, request, session, redirect
from flask_mysqldb import MySQL

app = Flask(__name__)
app.secret_key = 'your secret key'

mysql = MySQL(app)

app.config['MYSQL_HOST'] = 'localhost'
app.config['MYSQL_USER'] = 'your mysql username'
app.config['MYSQL_PASSWORD'] = 'your mysql password'
app.config['MYSQL_DB'] = 'your mysql database'

@app.route('/')
def index():
    if 'username' in session:
        return f'Hello, {session["username"]}!'
    else:
        return 'Please login first.'

@app.route('/signup', methods=['GET', 'POST'])
def signup():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']
        cur = mysql.connection.cursor()
        cur.execute('INSERT INTO users(username, password) VALUES (%s, %s)', (username, password))
        mysql.connection.commit()
        cur.close()
        session['username'] = username
        return redirect('/')
    else:
        return '''
               <form method="post">
               <input type="text" name="username" placeholder="Username"/><br>
               <input type="password" name="password" placeholder="Password"/><br>
               <button type="submit">Signup</button>
               </form>
               '''

@app.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']
        cur = mysql.connection.cursor()
        cur.execute('SELECT password FROM users WHERE username = %s', [username])
        password_from_db = cur.fetchone()
        cur.close()
        if password_from_db and password_from_db[0] == password:
            session['username'] = username
            return redirect('/')
        else:
            return 'Invalid username or password.'
    else:
        return '''
               <form method="post">
               <input type="text" name="username" placeholder="Username"/><br>
               <input type="password" name="password" placeholder="Password"/><br>
               <button type="submit">Login</button>
               </form>
               '''

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

以上代码使用 Flask 框架和 Flask-MySQLdb 扩展实现用户注册和登录功能。用户信息保存在 MySQL 数据库中，密码使用明文存储（实际应用中应使用加密后的密码）。