Python实例题：基于 Flask 的在线聊天系统

狐凄2025-07-04 10:14

目录

Python实例题

题目

要求：

解题思路：

代码实现：

Python实例题

题目

基于 Flask 的在线聊天系统

要求：

  • 使用 Flask 框架构建一个实时在线聊天系统，支持以下功能：
    • 用户注册、登录和个人资料管理
    • 一对一实时聊天功能
    • 群聊功能
    • 消息通知和未读消息提示
    • 在线用户状态显示
  • 使用 Flask-SocketIO 实现实时通信。
  • 使用 SQLite 数据库存储用户、聊天记录等信息。
  • 添加美观的前端界面，支持响应式设计。

解题思路：

  • 使用 Flask 蓝图组织代码结构。
  • 通过 Flask-Login 处理用户认证。
  • 使用 Flask-SocketIO 实现实时消息推送。
  • 使用 Flask-SQLAlchemy 管理数据库操作。
  • 结合 Bootstrap 实现美观的前端界面。

代码实现：

python 复制代码 
from flask import Flask, render_template, request, redirect, url_for, flash, session, Blueprint
from flask_sqlalchemy import SQLAlchemy
from flask_login import LoginManager, UserMixin, login_user, logout_user, login_required, current_user
from werkzeug.security import generate_password_hash, check_password_hash
from flask_socketio import SocketIO, emit, join_room, leave_room, send
import os
import time
from datetime import datetime

# 初始化 Flask 应用
app = Flask(__name__)
app.config['SECRET_KEY'] = 'your-secret-key-here'
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///' + os.path.join(app.root_path, 'chat.db')
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False

# 初始化数据库
db = SQLAlchemy(app)

# 初始化 Flask-Login
login_manager = LoginManager()
login_manager.init_app(app)
login_manager.login_view = 'auth.login'

# 初始化 SocketIO
socketio = SocketIO(app, async_mode='eventlet')

# 数据模型
class User(UserMixin, db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(80), unique=True, nullable=False)
    password_hash = db.Column(db.String(120), nullable=False)
    avatar = db.Column(db.String(100), default='default.png')
    online = db.Column(db.Boolean, default=False)
    last_seen = db.Column(db.DateTime)
    messages_sent = db.relationship('Message', foreign_keys='Message.sender_id',
                                   backref='sender', lazy='dynamic')
    messages_received = db.relationship('Message', foreign_keys='Message.recipient_id',
                                      backref='recipient', lazy='dynamic')
    
    def set_password(self, password):
        self.password_hash = generate_password_hash(password)
    
    def check_password(self, password):
        return check_password_hash(self.password_hash, password)
    
    def get_unread_messages_count(self):
        return Message.query.filter_by(recipient_id=self.id, read=False).count()

class Message(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    sender_id = db.Column(db.Integer, db.ForeignKey('user.id'))
    recipient_id = db.Column(db.Integer, db.ForeignKey('user.id'))
    content = db.Column(db.Text, nullable=False)
    timestamp = db.Column(db.DateTime, default=datetime.utcnow)
    read = db.Column(db.Boolean, default=False)

class ChatRoom(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(100), nullable=False)
    is_group = db.Column(db.Boolean, default=False)
    creator_id = db.Column(db.Integer, db.ForeignKey('user.id'))
    members = db.relationship('User', secondary='chat_room_member', backref='chat_rooms')

class ChatRoomMember(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    chat_room_id = db.Column(db.Integer, db.ForeignKey('chat_room.id'))
    user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
    joined_at = db.Column(db.DateTime, default=datetime.utcnow)

class GroupMessage(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    chat_room_id = db.Column(db.Integer, db.ForeignKey('chat_room.id'))
    sender_id = db.Column(db.Integer, db.ForeignKey('user.id'))
    content = db.Column(db.Text, nullable=False)
    timestamp = db.Column(db.DateTime, default=datetime.utcnow)

# 用户加载回调
@login_manager.user_loader
def load_user(user_id):
    return User.query.get(int(user_id))

# 认证蓝图
auth = Blueprint('auth', __name__)

@auth.route('/register', methods=['GET', 'POST'])
def register():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']
        
        if User.query.filter_by(username=username).first():
            flash('用户名已存在', 'error')
            return redirect(url_for('auth.register'))
        
        user = User(username=username)
        user.set_password(password)
        db.session.add(user)
        db.session.commit()
        
        flash('注册成功，请登录', 'success')
        return redirect(url_for('auth.login'))
    
    return render_template('register.html')

@auth.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']
        
        user = User.query.filter_by(username=username).first()
        
        if user and user.check_password(password):
            login_user(user)
            user.online = True
            user.last_seen = datetime.utcnow()
            db.session.commit()
            
            # 存储用户会话信息
            session['user_id'] = user.id
            
            flash('登录成功', 'success')
            return redirect(url_for('main.index'))
        else:
            flash('用户名或密码错误', 'error')
    
    return render_template('login.html')

@auth.route('/logout')
@login_required
def logout():
    # 更新用户在线状态
    user = User.query.get(current_user.id)
    user.online = False
    user.last_seen = datetime.utcnow()
    db.session.commit()
    
    logout_user()
    flash('已注销', 'success')
    return redirect(url_for('auth.login'))

# 主蓝图
main = Blueprint('main', __name__)

@main.route('/')
@login_required
def index():
    # 获取所有用户（除当前用户外）
    users = User.query.filter(User.id != current_user.id).order_by(User.username).all()
    
    # 获取当前用户的所有聊天组
    chat_rooms = ChatRoom.query.join(ChatRoomMember).filter(
        ChatRoomMember.user_id == current_user.id
    ).all()
    
    # 获取未读消息数量
    unread_counts = {}
    for user in users:
        unread_counts[user.id] = Message.query.filter_by(
            recipient_id=current_user.id,
            sender_id=user.id,
            read=False
        ).count()
    
    return render_template('index.html', users=users, chat_rooms=chat_rooms, unread_counts=unread_counts)

@main.route('/user/<int:user_id>/chat')
@login_required
def user_chat(user_id):
    recipient = User.query.get_or_404(user_id)
    
    # 将当前对话的消息标记为已读
    Message.query.filter_by(
        sender_id=recipient.id,
        recipient_id=current_user.id,
        read=False
    ).update({Message.read: True})
    db.session.commit()
    
    # 获取所有用户（除当前用户外）
    users = User.query.filter(User.id != current_user.id).order_by(User.username).all()
    
    # 获取当前用户的所有聊天组
    chat_rooms = ChatRoom.query.join(ChatRoomMember).filter(
        ChatRoomMember.user_id == current_user.id
    ).all()
    
    # 获取未读消息数量
    unread_counts = {}
    for user in users:
        unread_counts[user.id] = Message.query.filter_by(
            recipient_id=current_user.id,
            sender_id=user.id,
            read=False
        ).count()
    
    return render_template('user_chat.html', recipient=recipient, users=users, 
                           chat_rooms=chat_rooms, unread_counts=unread_counts)

@main.route('/group/<int:group_id>/chat')
@login_required
def group_chat(group_id):
    chat_room = ChatRoom.query.get_or_404(group_id)
    
    # 检查当前用户是否是该组的成员
    is_member = ChatRoomMember.query.filter_by(
        chat_room_id=group_id,
        user_id=current_user.id
    ).first() is not None
    
    if not is_member:
        flash('你不是该组的成员', 'error')
        return redirect(url_for('main.index'))
    
    # 获取所有用户（除当前用户外）
    users = User.query.filter(User.id != current_user.id).order_by(User.username).all()
    
    # 获取当前用户的所有聊天组
    chat_rooms = ChatRoom.query.join(ChatRoomMember).filter(
        ChatRoomMember.user_id == current_user.id
    ).all()
    
    # 获取未读消息数量
    unread_counts = {}
    for user in users:
        unread_counts[user.id] = Message.query.filter_by(
            recipient_id=current_user.id,
            sender_id=user.id,
            read=False
        ).count()
    
    return render_template('group_chat.html', chat_room=chat_room, users=users, 
                           chat_rooms=chat_rooms, unread_counts=unread_counts)

@main.route('/create-group', methods=['GET', 'POST'])
@login_required
def create_group():
    if request.method == 'POST':
        group_name = request.form['group_name']
        member_ids = request.form.getlist('members')
        
        if not group_name:
            flash('组名不能为空', 'error')
            return redirect(url_for('main.create_group'))
        
        # 创建新组
        group = ChatRoom(name=group_name, is_group=True, creator_id=current_user.id)
        db.session.add(group)
        db.session.commit()
        
        # 添加创建者为成员
        member = ChatRoomMember(chat_room_id=group.id, user_id=current_user.id)
        db.session.add(member)
        
        # 添加其他成员
        for member_id in member_ids:
            if int(member_id) != current_user.id:
                member = ChatRoomMember(chat_room_id=group.id, user_id=member_id)
                db.session.add(member)
        
        db.session.commit()
        
        flash('组创建成功', 'success')
        return redirect(url_for('main.group_chat', group_id=group.id))
    
    # 获取所有用户（除当前用户外）
    users = User.query.filter(User.id != current_user.id).order_by(User.username).all()
    
    return render_template('create_group.html', users=users)

@main.route('/profile', methods=['GET', 'POST'])
@login_required
def profile():
    if request.method == 'POST':
        username = request.form['username']
        avatar = request.form['avatar']
        
        if username != current_user.username and User.query.filter_by(username=username).first():
            flash('用户名已存在', 'error')
            return redirect(url_for('main.profile'))
        
        current_user.username = username
        current_user.avatar = avatar
        db.session.commit()
        
        flash('个人资料已更新', 'success')
        return redirect(url_for('main.profile'))
    
    return render_template('profile.html')

# SocketIO 事件处理
@socketio.on('connect')
def handle_connect():
    user_id = session.get('user_id')
    if user_id:
        user = User.query.get(user_id)
        if user:
            user.online = True
            user.last_seen = datetime.utcnow()
            db.session.commit()
            
            # 通知所有在线用户更新用户状态
            update_user_status(user)

@socketio.on('disconnect')
def handle_disconnect():
    user_id = session.get('user_id')
    if user_id:
        user = User.query.get(user_id)
        if user:
            user.online = False
            user.last_seen = datetime.utcnow()
            db.session.commit()
            
            # 通知所有在线用户更新用户状态
            update_user_status(user)

@socketio.on('private_message')
def handle_private_message(data):
    sender_id = session.get('user_id')
    recipient_id = data['recipient_id']
    content = data['content']
    
    if sender_id and recipient_id and content:
        # 保存消息到数据库
        message = Message(
            sender_id=sender_id,
            recipient_id=recipient_id,
            content=content
        )
        db.session.add(message)
        db.session.commit()
        
        # 发送消息给接收者
        recipient = User.query.get(recipient_id)
        if recipient.online:
            emit('new_message', {
                'sender_id': sender_id,
                'recipient_id': recipient_id,
                'content': content,
                'timestamp': message.timestamp.strftime('%Y-%m-%d %H:%M:%S')
            }, room=str(recipient_id))
        
        # 发送消息给发送者自己
        emit('new_message', {
            'sender_id': sender_id,
            'recipient_id': recipient_id,
            'content': content,
            'timestamp': message.timestamp.strftime('%Y-%m-%d %H:%M:%S')
        }, room=str(sender_id))

@socketio.on('join_room')
def handle_join_room(data):
    room_id = data['room_id']
    join_room(room_id)

@socketio.on('leave_room')
def handle_leave_room(data):
    room_id = data['room_id']
    leave_room(room_id)

@socketio.on('group_message')
def handle_group_message(data):
    sender_id = session.get('user_id')
    chat_room_id = data['chat_room_id']
    content = data['content']
    
    if sender_id and chat_room_id and content:
        # 保存消息到数据库
        group_message = GroupMessage(
            chat_room_id=chat_room_id,
            sender_id=sender_id,
            content=content
        )
        db.session.add(group_message)
        db.session.commit()
        
        # 发送消息到群组
        emit('new_group_message', {
            'sender_id': sender_id,
            'chat_room_id': chat_room_id,
            'content': content,
            'timestamp': group_message.timestamp.strftime('%Y-%m-%d %H:%M:%S')
        }, room=str(chat_room_id))

def update_user_status(user):
    """通知所有在线用户更新用户状态"""
    emit('user_status_update', {
        'user_id': user.id,
        'online': user.online,
        'last_seen': user.last_seen.strftime('%Y-%m-%d %H:%M:%S') if user.last_seen else ''
    }, broadcast=True)

# 注册蓝图
app.register_blueprint(main)
app.register_blueprint(auth)

# 创建数据库表
with app.app_context():
    db.create_all()

if __name__ == '__main__':
    socketio.run(app, debug=True)
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