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七、讨论区系统实现

1. 完善的评论模型设计（discussion/models.py）

python

复制

from django.db import models
from django.contrib.auth import get_user_model
from courses.models import Course

User = get_user_model()

class CourseComment(models.Model):
    """
    课程评论模型
    - 支持多级评论（通过parent字段自关联实现）
    - 支持点赞功能（通过likes多对多关系实现）
    - 自动记录创建时间
    """
    course = models.ForeignKey(
        Course,
        on_delete=models.CASCADE,
        related_name='comments',
        verbose_name='所属课程'
    )
    user = models.ForeignKey(
        User,
        on_delete=models.CASCADE,
        related_name='comments',
        verbose_name='评论用户'
    )
    content = models.TextField(
        verbose_name='评论内容',
        max_length=2000,
        help_text='评论内容最多2000个字符'
    )
    created_at = models.DateTimeField(
        auto_now_add=True,
        verbose_name='创建时间'
    )
    parent = models.ForeignKey(
        'self',
        null=True,
        blank=True,
        on_delete=models.CASCADE,
        related_name='replies',
        verbose_name='父级评论'
    )
    likes = models.ManyToManyField(
        User,
        related_name='liked_comments',
        verbose_name='点赞用户',
        blank=True
    )

    class Meta:
        verbose_name = '课程评论'
        verbose_name_plural = '课程评论'
        ordering = ['-created_at']  # 按创建时间降序排列
        indexes = [
            models.Index(fields=['created_at'], name='comment_created_idx'),
            models.Index(fields=['course'], name='comment_course_idx'),
        ]

    def __str__(self):
        return f"{self.user.username}的评论：{self.content[:20]}..."

    @property
    def like_count(self):
        """获取点赞数量"""
        return self.likes.count()

    def get_replies(self):
        """获取所有子回复（按时间正序排列）"""
        return self.replies.all().order_by('created_at')

    def has_parent(self):
        """判断是否有父级评论"""
        return self.parent is not None

2. 序列化器（discussion/serializers.py）

python

复制

from rest_framework import serializers
from .models import CourseComment
from django.contrib.auth import get_user_model

User = get_user_model()

class UserSerializer(serializers.ModelSerializer):
    """用户信息序列化器"""
    class Meta:
        model = User
        fields = ['id', 'username', 'avatar']

class CourseCommentSerializer(serializers.ModelSerializer):
    """评论序列化器（包含嵌套回复）"""
    user = UserSerializer(read_only=True)  # 嵌套用户信息
    replies = serializers.SerializerMethodField()  # 自定义回复字段
    like_count = serializers.SerializerMethodField()  # 点赞数
    is_liked = serializers.SerializerMethodField()  # 当前用户是否点赞

    class Meta:
        model = CourseComment
        fields = [
            'id', 'user', 'content', 'created_at', 
            'parent', 'replies', 'like_count', 'is_liked'
        ]
        read_only_fields = ['user', 'created_at']

    def get_replies(self, obj):
        """获取子回复（递归序列化）"""
        if obj.replies.exists():
            return CourseCommentSerializer(
                obj.get_replies(),
                many=True,
                context=self.context
            ).data
        return None

    def get_like_count(self, obj):
        """获取点赞数量"""
        return obj.like_count

    def get_is_liked(self, obj):
        """检查当前用户是否点赞"""
        request = self.context.get('request')
        if request and request.user.is_authenticated:
            return obj.likes.filter(id=request.user.id).exists()
        return False

    def create(self, validated_data):
        """创建评论时自动关联用户"""
        validated_data['user'] = self.context['request'].user
        return super().create(validated_data)

3. 视图（discussion/views.py）

python

复制

from rest_framework import viewsets, permissions, status
from rest_framework.decorators import action
from rest_framework.response import Response
from .models import CourseComment
from .serializers import CourseCommentSerializer

class CourseCommentViewSet(viewsets.ModelViewSet):
    """
    评论视图集：
    - 支持评论的CRUD操作
    - 支持点赞功能
    - 按课程过滤评论
    """
    serializer_class = CourseCommentSerializer
    permission_classes = [permissions.IsAuthenticatedOrReadOnly]

    def get_queryset(self):
        """根据课程ID过滤顶级评论"""
        queryset = CourseComment.objects.filter(parent__isnull=True)
        course_id = self.request.query_params.get('course_id')
        if course_id:
            queryset = queryset.filter(course_id=course_id)
        return queryset.prefetch_related('replies')

    @action(detail=True, methods=['post'])
    def like(self, request, pk=None):
        """点赞/取消点赞"""
        comment = self.get_object()
        user = request.user

        if comment.likes.filter(id=user.id).exists():
            comment.likes.remove(user)
            status_code = status.HTTP_200_OK
            message = '取消点赞成功'
        else:
            comment.likes.add(user)
            status_code = status.HTTP_201_CREATED
            message = '点赞成功'

        return Response({'message': message}, status=status_code)

    def perform_create(self, serializer):
        """创建评论时自动关联用户和课程"""
        course_id = self.request.data.get('course')
        serializer.save(user=self.request.user, course_id=course_id)

4. 路由配置（discussion/urls.py）

python

复制

from django.urls import path, include
from rest_framework.routers import DefaultRouter
from .views import CourseCommentViewSet

router = DefaultRouter()
router.register(r'comments', CourseCommentViewSet, basename='comment')

urlpatterns = [
    path('', include(router.urls)),
]

5. 评论列表组件（lib/components/comment_list.dart）

dart

复制

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'package:provider/provider.dart';
import 'dart:convert';

class CommentList extends StatefulWidget {
  final String courseId;

  const CommentList({Key? key, required this.courseId}) : super(key: key);

  @override
  _CommentListState createState() => _CommentListState();
}

class _CommentListState extends State {
  List _comments = [];
  bool _isLoading = true;

  @override
  void initState() {
    super.initState();
    _fetchComments();
  }

  Future _fetchComments() async {
    final response = await http.get(
      Uri.parse('http://your-api.com/api/comments/?course_id=${widget.courseId}'),
      headers: {'Authorization': 'Bearer ${_getToken()}'},
    );

    if (response.statusCode == 200) {
      setState(() {
        _comments = jsonDecode(response.body);
        _isLoading = false;
      });
    }
  }

  String _getToken() {
    // 从安全存储获取token
    return 'user_auth_token';
  }

  @override
  Widget build(BuildContext context) {
    return _isLoading
        ? Center(child: CircularProgressIndicator())
        : ListView.builder(
            itemCount: _comments.length,
            itemBuilder: (context, index) => CommentItem(
              comment: _comments[index],
              onLike: _handleLike,
            ),
          );
  }

  void _handleLike(int commentId) async {
    final response = await http.post(
      Uri.parse('http://your-api.com/api/comments/$commentId/like/'),
      headers: {'Authorization': 'Bearer ${_getToken()}'},
    );

    if (response.statusCode == 200) {
      _fetchComments(); // 刷新评论列表
    }
  }
}

class CommentItem extends StatelessWidget {
  final Map comment;
  final Function(int) onLike;

  const CommentItem({
    Key? key,
    required this.comment,
    required this.onLike,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Card(
      margin: EdgeInsets.symmetric(vertical: 8),
      child: Padding(
        padding: EdgeInsets.all(12),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            _buildHeader(),
            SizedBox(height: 8),
            Text(comment['content']),
            _buildLikeButton(),
            if (comment['replies'] != null)
              ...comment['replies'].map((reply) => Padding(
                padding: EdgeInsets.only(left: 24, top: 8),
                child: CommentItem(
                  comment: reply,
                  onLike: onLike,
                ),
              )),
          ],
        ),
      ),
    );
  }

  Widget _buildHeader() {
    return Row(
      children: [
        CircleAvatar(
          backgroundImage: NetworkImage(comment['user']['avatar'] ?? ''),
        SizedBox(width: 8),
        Text(comment['user']['username']),
        Spacer(),
        Text(
          _formatDate(comment['created_at']),
          style: TextStyle(color: Colors.grey),
        ),
      ],
    );
  }

  Widget _buildLikeButton() {
    return Row(
      mainAxisAlignment: MainAxisAlignment.end,
      children: [
        IconButton(
          icon: Icon(
            comment['is_liked'] ? Icons.favorite : Icons.favorite_border,
            color: comment['is_liked'] ? Colors.red : null,
          ),
          onPressed: () => onLike(comment['id']),
        ),
        Text(comment['like_count'].toString()),
      ],
    );
  }

  String _formatDate(String dateStr) {
    final date = DateTime.parse(dateStr);
    return '${date.year}-${date.month}-${date.day}';
  }
}

6. 评论发布组件（lib/components/comment_input.dart）

dart

复制

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;

class CommentInput extends StatefulWidget {
  final String courseId;
  final VoidCallback onCommentAdded;

  const CommentInput({
    Key? key,
    required this.courseId,
    required this.onCommentAdded,
  }) : super(key: key);

  @override
  _CommentInputState createState() => _CommentInputState();
}

class _CommentInputState extends State {
  final _controller = TextEditingController();
  bool _isSubmitting = false;

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: EdgeInsets.all(16),
      child: Row(
        children: [
          Expanded(
            child: TextField(
              controller: _controller,
              decoration: InputDecoration(
                hintText: '写下你的评论...',
                border: OutlineInputBorder(),
              ),
              maxLines: 3,
            ),
          ),
          SizedBox(width: 8),
          _isSubmitting
              ? CircularProgressIndicator()
              : IconButton(
                  icon: Icon(Icons.send),
                  onPressed: _submitComment,
                ),
        ],
      ),
    );
  }

  Future _submitComment() async {
    if (_controller.text.isEmpty) return;

    setState(() => _isSubmitting = true);

    final response = await http.post(
      Uri.parse('http://your-api.com/api/comments/'),
      headers: {
        'Authorization': 'Bearer ${_getToken()}',
        'Content-Type': 'application/json',
      },
      body: jsonEncode({
        'course': widget.courseId,
        'content': _controller.text,
      }),
    );

    setState(() => _isSubmitting = false);

    if (response.statusCode == 201) {
      _controller.clear();
      widget.onCommentAdded();
    }
  }

  String _getToken() {
    // 从安全存储获取token
    return 'user_auth_token';
  }
}

7、系统功能验证

测试用例

（1）发布评论

（2）点赞功能

（3）查看回复

八、推荐系统深度实现

1. 推荐系统架构

bash

复制

推荐流程：
用户行为收集 -> 特征工程 -> 推荐算法 -> 结果缓存 -> API接口暴露

2. 用户行为日志设计

python

复制

# analytics/models.py
from django.db import models
from django.contrib.auth import get_user_model
from courses.models import Course

User = get_user_model()

class UserBehavior(models.Model):
    EVENT_TYPES = [
        ('view', '浏览'),
        ('enroll', '报名'),
        ('play', '播放'),
        ('search', '搜索'),
        ('share', '分享')
    ]
    
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    course = models.ForeignKey(Course, null=True, on_delete=models.SET_NULL)
    event_type = models.CharField(max_length=20, choices=EVENT_TYPES)
    event_data = models.JSONField(default=dict)
    created_at = models.DateTimeField(auto_now_add=True)
    
    class Meta:
        indexes = [
            models.Index(fields=['user', 'event_type']),
            models.Index(fields=['course', 'event_type'])
        ]

3. 混合推荐算法实现

python

复制

# recommendations/algorithms.py
import numpy as np
from collections import defaultdict
from django.db.models import Count
from courses.models import Course, Enrollment

class HybridRecommender:
    def __init__(self, user):
        self.user = user
        self.content_weight = 0.6
        self.collaborative_weight = 0.4

    def get_recommendations(self, num=10):
        # 内容推荐
        content_scores = self._content_based_filtering()
        
        # 协同过滤
        collab_scores = self._collaborative_filtering()
        
        # 混合推荐
        combined = defaultdict(float)
        for course_id in set(content_scores.keys()) | set(collab_scores.keys()):
            combined[course_id] = (
                content_scores.get(course_id, 0) * self.content_weight +
                collab_scores.get(course_id, 0) * self.collaborative_weight
            )
        
        # 获取推荐课程
        sorted_ids = sorted(combined.items(), key=lambda x: x[1], reverse=True)[:num]
        return Course.objects.filter(id__in=[cid for cid, _ in sorted_ids])

    def _content_based_filtering(self):
        # 基于用户已学课程的特征推荐
        user_courses = Course.objects.filter(enrollment__student=self.user)
        if not user_courses.exists():
            return self._popular_courses()
            
        # 计算课程特征向量
        features = defaultdict(float)
        for course in user_courses:
            features[course.category_id] += 1
            features[f"level_{course.level}"] += 1
        
        # 寻找相似课程
        scores = {}
        for course in Course.objects.exclude(enrollment__student=self.user):
            score = 0
            if course.category_id in features:
                score += features[course.category_id] * 0.7
            if f"level_{course.level}" in features:
                score += features[f"level_{course.level}"] * 0.3
            scores[course.id] = score
            
        return scores

    def _collaborative_filtering(self):
        # 基于用户的协同过滤
        user_enrollments = set(Enrollment.objects.filter(student=self.user)
                              .values_list('course_id', flat=True))
        
        # 找到相似用户
        similar_users = (Enrollment.objects.exclude(student=self.user)
                        .filter(course_id__in=user_enrollments)
                        .values('student')
                        .annotate(common=Count('course_id'))
                        .order_by('-common')[:5])
        
        # 收集相似用户的课程
        scores = defaultdict(int)
        for user in similar_users:
            for course in Enrollment.objects.filter(student=user['student']):
                if course.course_id not in user_enrollments:
                    scores[course.course_id] += user['common']
        
        return scores

    def _popular_courses(self):
        # 热门课程回退策略
        return dict(Course.objects.annotate(popularity=Count('enrollment'))
                     .order_by('-popularity')[:10]
                     .values_list('id', 'popularity'))

4. 推荐API实现

python

复制

# recommendations/views.py
from rest_framework.views import APIView
from rest_framework.response import Response
from .algorithms import HybridRecommender
from courses.serializers import CourseSerializer

class RecommendationAPI(APIView):
    def get(self, request):
        recommender = HybridRecommender(request.user)
        courses = recommender.get_recommendations(10)
        serializer = CourseSerializer(courses, many=True)
        return Response({
            'recommendations': serializer.data,
            'algorithm': 'hybrid'
        })

九、用户个人中心完整实现

1. 用户模型扩展

python

复制

# users/models.py
from django.db import models
from django.contrib.auth.models import AbstractUser
from django.utils.translation import gettext_lazy as _

class User(AbstractUser):
    USER_TYPES = [
        ('student', '学生'),
        ('teacher', '教师'),
        ('admin', '管理员')
    ]
    
    avatar = models.ImageField(upload_to='avatars/', null=True)
    bio = models.TextField(_('个人简介'), blank=True)
    user_type = models.CharField(max_length=10, choices=USER_TYPES, default='student')
    phone = models.CharField(max_length=20, blank=True)
    location = models.CharField(max_length=100, blank=True)
    
    class Meta:
        verbose_name = _('用户')
        verbose_name_plural = _('用户')

class UserAchievement(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    title = models.CharField(max_length=100)
    description = models.TextField()
    achieved_at = models.DateTimeField(auto_now_add=True)
    icon = models.CharField(max_length=50)

2. 个人中心API

python

复制

# users/views.py
from rest_framework.viewsets import ModelViewSet
from rest_framework.decorators import action
from rest_framework.permissions import IsAuthenticated
from .models import User, UserAchievement
from .serializers import UserSerializer, AchievementSerializer

class UserProfileViewSet(ModelViewSet):
    queryset = User.objects.all()
    serializer_class = UserSerializer
    permission_classes = [IsAuthenticated]

    @action(detail=False, methods=['get', 'put'])
    def me(self, request):
        user = request.user
        if request.method == 'GET':
            serializer = self.get_serializer(user)
            return Response(serializer.data)
        elif request.method == 'PUT':
            serializer = self.get_serializer(user, data=request.data)
            serializer.is_valid(raise_exception=True)
            serializer.save()
            return Response(serializer.data)

    @action(detail=True, methods=['get'])
    def achievements(self, request, pk=None):
        user = self.get_object()
        achievements = UserAchievement.objects.filter(user=user)
        serializer = AchievementSerializer(achievements, many=True)
        return Response(serializer.data)

3. Flutter个人中心界面

dart

复制

// lib/screens/profile_screen.dart
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import '../providers/auth_provider.dart';
import '../widgets/achievement_badge.dart';

class ProfileScreen extends StatelessWidget {
  const ProfileScreen({super.key});

  @override
  Widget build(BuildContext context) {
    final authProvider = Provider.of(context);
    final user = authProvider.user;

    return Scaffold(
      appBar: AppBar(title: const Text('个人中心')),
      body: SingleChildScrollView(
        child: Column(
          children: [
            _buildProfileHeader(user),
            _buildStatisticsSection(),
            _buildAchievementsSection(),
            _buildSettingsSection(),
          ],
        ),
      ),
    );
  }

  Widget _buildProfileHeader(User user) {
    return Container(
      padding: const EdgeInsets.all(20),
      decoration: BoxDecoration(
        color: Colors.blue[50],
        borderRadius: BorderRadius.circular(12),
      ),
      child: Row(
        children: [
          CircleAvatar(
            radius: 40,
            backgroundImage: user.avatarUrl != null 
                ? NetworkImage(user.avatarUrl!)
                : const AssetImage('assets/default_avatar.png') as ImageProvider,
          ),
          const SizedBox(width: 20),
          Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                user.username,
                style: const TextStyle(
                  fontSize: 24,
                  fontWeight: FontWeight.bold,
                ),
              ),
              Text(user.bio ?? '暂无个人简介'),
              Chip(
                label: Text(user.userType),
                backgroundColor: _getUserTypeColor(user.userType),
              ),
            ],
          ),
        ],
      ),
    );
  }

  Widget _buildStatisticsSection() {
    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Row(
          mainAxisAlignment: MainAxisAlignment.spaceAround,
          children: [
            _buildStatItem('已学课程', '128'),
            _buildStatItem('学习时长', '256h'),
            _buildStatItem('成就点数', '980'),
          ],
        ),
      ),
    );
  }

  Widget _buildAchievementsSection() {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        const Padding(
          padding: EdgeInsets.all(16),
          child: Text(
            '学习成就',
            style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
          ),
        ),
        SizedBox(
          height: 120,
          child: ListView.builder(
            scrollDirection: Axis.horizontal,
            itemCount: 5,
            itemBuilder: (context, index) => const AchievementBadge(),
          ),
        ),
      ],
    );
  }

  Widget _buildSettingsSection() {
    return Column(
      children: [
        ListTile(
          leading: const Icon(Icons.edit),
          title: const Text('编辑资料'),
          onTap: () => _navigateToEditProfile(context),
        ),
        ListTile(
          leading: const Icon(Icons.security),
          title: const Text('账户安全'),
          onTap: () {},
        ),
        ListTile(
          leading: const Icon(Icons.notifications),
          title: const Text('通知设置'),
          onTap: () {},
        ),
      ],
    );
  }

  Color _getUserTypeColor(String type) {
    switch (type) {
      case 'teacher':
        return Colors.amber[200]!;
      case 'admin':
        return Colors.red[200]!;
      default:
        return Colors.green[200]!;
    }
  }

  Widget _buildStatItem(String label, String value) {
    return Column(
      children: [
        Text(
          value,
          style: const TextStyle(
            fontSize: 20,
            fontWeight: FontWeight.bold,
          ),
        ),
        Text(
          label,
          style: TextStyle(
            color: Colors.grey[600],
            fontSize: 14,
          ),
        ),
      ],
    );
  }
}

十、教师管理后台实现

1. 教师权限管理

python

复制

# courses/permissions.py
from rest_framework.permissions import BasePermission

class IsCourseTeacher(BasePermission):
    def has_object_permission(self, request, view, obj):
        return obj.teacher == request.user

class IsTeacherUser(BasePermission):
    def has_permission(self, request, view):
        return request.user.user_type == 'teacher'

2. 教学数据统计API

python

复制

# analytics/views.py
from rest_framework.views import APIView
from rest_framework.response import Response
from django.db.models import Count, Avg
from courses.models import Course, Enrollment

class TeachingAnalyticsAPI(APIView):
    permission_classes = [IsTeacherUser]

    def get(self, request):
        teacher = request.user
        courses = Course.objects.filter(teacher=teacher)
        
        # 基础统计
        total_students = Enrollment.objects.filter(course__teacher=teacher)
                             .values('student').distinct().count()
        total_income = sum(course.price * course.enrollment_set.count() 
                          for course in courses)
        
        # 课程评分数据
        rating_stats = courses.annotate(
            avg_rating=Avg('reviews__rating'),
            review_count=Count('reviews')
        ).values('title', 'avg_rating', 'review_count')
        
        # 学习进度统计
        progress_data = []
        for course in courses:
            completed = course.enrollment_set.filter(completed=True).count()
            total = course.enrollment_set.count()
            progress_data.append({
                'course': course.title,
                'completion_rate': completed / total * 100 if total > 0 else 0
            })
        
        return Response({
            'total_courses': courses.count(),
            'total_students': total_students,
            'total_income': total_income,
            'rating_stats': rating_stats,
            'progress_data': progress_data
        })

3. Flutter教师仪表盘

dart

复制

// lib/screens/teacher_dashboard.dart
import 'package:flutter/material.dart';
import 'package:charts_flutter/flutter.dart' as charts;

class TeacherDashboard extends StatelessWidget {
  final Map analyticsData;

  const TeacherDashboard({super.key, required this.analyticsData});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('教学仪表盘')),
      body: ListView(
        padding: const EdgeInsets.all(16),
        children: [
          _buildStatsGrid(),
          const SizedBox(height: 24),
          _buildRatingChart(),
          const SizedBox(height: 24),
          _buildProgressChart(),
        ],
      ),
    );
  }

  Widget _buildStatsGrid() {
    return GridView.count(
      shrinkWrap: true,
      crossAxisCount: 2,
      childAspectRatio: 2,
      crossAxisSpacing: 16,
      mainAxisSpacing: 16,
      children: [
        _buildStatCard('总课程数', analyticsData['total_courses'].toString()),
        _buildStatCard('总学生数', analyticsData['total_students'].toString()),
        _buildStatCard('总收入', 'yen${analyticsData['total_income'].toStringAsFixed(2)}'),
        _buildStatCard('平均评分', analyticsData['rating_stats'].isNotEmpty 
            ? analyticsData['rating_stats'][0]['avg_rating'].toStringAsFixed(1)
            : '0.0'),
      ],
    );
  }

  Widget _buildRatingChart() {
    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            const Text(
              '课程评分分布',
              style: TextStyle(fontWeight: FontWeight.bold),
            ),
            SizedBox(
              height: 200,
              child: charts.BarChart(
                _createRatingSeries(),
                animate: true,
                domainAxis: const charts.OrdinalAxisSpec(
                  renderSpec: charts.SmallTickRendererSpec(
                    labelRotation: 45,
                  ),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }

  List<charts.Series<Map, String>> _createRatingSeries() {
    return [
      charts.Series(
        id: 'Ratings',
        data: analyticsData['rating_stats'],
        domainFn: (item, _) => item['title'],
        measureFn: (item, _) => item['avg_rating'] ?? 0,
        colorFn: (_, __) => charts.MaterialPalette.blue.shadeDefault,
      )
    ];
  }

  Widget _buildStatCard(String title, String value) {
    return Card(
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(
              value,
              style: const TextStyle(
                fontSize: 24,
                fontWeight: FontWeight.bold,
              ),
            ),
            Text(
              title,
              style: TextStyle(
                color: Colors.grey[600],
                fontSize: 14,
              ),
            ),
          ],
        ),
      ),
    );
  }
}

十一、系统安全加固措施

1. 安全中间件配置

python

复制

# edu_platform/settings.py
SECURE_CONTENT_TYPE_NOSNIFF = True
SECURE_BROWSER_XSS_FILTER = True
X_FRAME_OPTIONS = 'DENY'
CSRF_COOKIE_HTTPONLY = True
SESSION_COOKIE_SECURE = True
CSRF_COOKIE_SECURE = True
SECURE_HSTS_SECONDS = 31536000  # 1 year
SECURE_HSTS_INCLUDE_SUBDOMAINS = True
SECURE_HSTS_PRELOAD = True
CORS_ORIGIN_WHITELIST = ['https://yourdomain.com']

2. 请求频率限制

python

复制

# utils/throttles.py
from rest_framework.throttling import UserRateThrottle

class BurstRateThrottle(UserRateThrottle):
    scope = 'burst'

class SustainedRateThrottle(UserRateThrottle):
    scope = 'sustained'

# settings.py配置
REST_FRAMEWORK = {
    'DEFAULT_THROTTLE_CLASSES': [
        'utils.throttles.BurstRateThrottle',
        'utils.throttles.SustainedRateThrottle'
    ],
    'DEFAULT_THROTTLE_RATES': {
        'burst': '100/minute',
        'sustained': '1000/day'
    }
}

3. 敏感操作审计日志（代码简略）

复制

# security/signals.py
from django.db.models.signals import post_save, post_delete
from django.dispatch import receiver
from django.contrib.admin.models import LogEntry, ADDITION, CHANGE, DELETION
from django.contrib.contenttypes.models import ContentType

十二、持续集成与自动化部署

1. GitLab CI/CD 配置

yaml

复制

# .gitlab-ci.yml
variables:
  DOCKER_IMAGE: registry.example.com/edu-platform
  PRODUCTION_SERVER: edu-prod.example.com

stages:
  - test
  - build
  - deploy

unit-test:
  stage: test
  image: python:3.9
  services:
    - postgres:13
  variables:
    DATABASE_URL: "postgres://postgres@postgres:5432/test_db"
  before_script:
    - apt-get update && apt-get install -y build-essential python3-dev
    - pip install -r requirements.txt
  script:
    - pytest --cov=edu_platform --cov-report=xml

build-docker:
  stage: build
  image: docker:20.10
  services:
    - docker:20.10-dind
  script:
    - docker build -t $DOCKER_IMAGE:$CI_COMMIT_SHA .
    - docker push $DOCKER_IMAGE:$CI_COMMIT_SHA

deploy-prod:
  stage: deploy
  image: alpine/ssh
  only:
    - main
  script:
    - ssh -o StrictHostKeyChecking=no deploy@$PRODUCTION_SERVER "
        docker pull $DOCKER_IMAGE:$CI_COMMIT_SHA && 
        docker service update --image $DOCKER_IMAGE:$CI_COMMIT_SHA edu_platform
      "

2. Docker 生产环境配置

Dockerfile

复制

# Dockerfile.prod
FROM python:3.9-slim

ENV PYTHONUNBUFFERED=1 \
    PYTHONDONTWRITEBYTECODE=1 \
    POETRY_VERSION=1.4.2

RUN apt-get update && \
    apt-get install -y --no-install-recommends \
    build-essential \
    libpq-dev \
    && rm -rf /var/lib/apt/lists/*

RUN pip install "poetry==$POETRY_VERSION"
COPY pyproject.toml poetry.lock ./
RUN poetry config virtualenvs.create false && \
    poetry install --no-interaction --no-ansi --only main

COPY . /app
WORKDIR /app

RUN python manage.py collectstatic --noinput

CMD ["gunicorn", "--bind", "0.0.0.0:8000", "--workers", "4", "edu_platform.wsgi"]

3. 监控告警配置

yaml

复制

# docker-compose.monitoring.yml
version: '3.8'

services:
  prometheus:
    image: prom/prometheus
    ports:
      - "9090:9090"
    volumes:
      - ./monitoring/prometheus.yml:/etc/prometheus/prometheus.yml
    command:
      - '--config.file=/etc/prometheus/prometheus.yml'

  grafana:
    image: grafana/grafana
    ports:
      - "3000:3000"
    volumes:
      - grafana-data:/var/lib/grafana
    depends_on:
      - prometheus

  node-exporter:
    image: prom/node-exporter
    ports:
      - "9100:9100"

volumes:
  grafana-data:

十三、消息通知系统

1. 通知模型设计

python

复制

# notifications/models.py
from django.db import models
from django.contrib.auth import get_user_model

User = get_user_model()

class Notification(models.Model):
    NOTIFICATION_TYPES = [
        ('system', '系统通知'),
        ('course', '课程通知'),
        ('payment', '支付通知'),
        ('live', '直播提醒')
    ]
    
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    title = models.CharField(max_length=200)
    content = models.TextField()
    notification_type = models.CharField(max_length=20, choices=NOTIFICATION_TYPES)
    is_read = models.BooleanField(default=False)
    created_at = models.DateTimeField(auto_now_add=True)
    related_object_id = models.CharField(max_length=100, null=True)
    
    class Meta:
        indexes = [
            models.Index(fields=['user', 'is_read']),
            models.Index(fields=['created_at'])
        ]
        ordering = ['-created_at']

2. WebSocket 通知推送

python

复制

# notifications/consumers.py
import json
from channels.generic.websocket import AsyncWebsocketConsumer
from channels.db import database_sync_to_async

class NotificationConsumer(AsyncWebsocketConsumer):
    async def connect(self):
        self.user = self.scope["user"]
        if self.user.is_authenticated:
            self.group_name = f"notifications_{self.user.id}"
            await self.channel_layer.group_add(
                self.group_name,
                self.channel_name
            )
            await self.accept()
        else:
            await self.close()

    async def disconnect(self, close_code):
        if hasattr(self, 'group_name'):
            await self.channel_layer.group_discard(
                self.group_name,
                self.channel_name
            )

    async def receive(self, text_data):
        data = json.loads(text_data)
        if data.get('action') == 'mark_read':
            await self.mark_notification_read(data['notification_id'])

    @database_sync_to_async
    def mark_notification_read(self, notification_id):
        Notification.objects.filter(
            id=notification_id, 
            user=self.user
        ).update(is_read=True)

    async def send_notification(self, event):
        await self.send(text_data=json.dumps({
            "type": "notification",
            "title": event["title"],
            "content": event["content"],
            "timestamp": event["timestamp"],
            "id": event["id"]
        }))

3. Flutter 消息中心实现

dart

复制

// lib/screens/notification_screen.dart
import 'package:flutter/material.dart';
import 'package:web_socket_channel/web_socket_channel.dart';

class NotificationScreen extends StatefulWidget {
  const NotificationScreen({super.key});

  @override
  _NotificationScreenState createState() => _NotificationScreenState();
}

class _NotificationScreenState extends State {
  late final WebSocketChannel _channel;
  final List _notifications = [];

  @override
  void initState() {
    super.initState();
    _channel = WebSocketChannel.connect(
      Uri.parse('wss://yourdomain.com/ws/notifications/'),
      headers: {'Authorization': 'Bearer ${userToken}'}
    );
    _channel.stream.listen(_handleMessage);
  }

  void _handleMessage(dynamic message) {
    final data = jsonDecode(message);
    setState(() {
      _notifications.insert(0, Notification(
        id: data['id'],
        title: data['title'],
        content: data['content'],
        timestamp: DateTime.parse(data['timestamp']),
        isRead: false
      ));
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('消息中心'),
        actions: [
          IconButton(
            icon: const Icon(Icons.mark_as_unread),
            onPressed: _markAllAsRead,
          )
        ],
      ),
      body: ListView.builder(
        itemCount: _notifications.length,
        itemBuilder: (context, index) => _buildNotificationItem(_notifications[index]),
      ),
    );
  }

  Widget _buildNotificationItem(Notification notification) {
    return Dismissible(
      key: Key(notification.id),
      background: Container(color: Colors.red),
      onDismissed: (_) => _deleteNotification(notification.id),
      child: ListTile(
        leading: _getNotificationIcon(notification.type),
        title: Text(notification.title),
        subtitle: Text(notification.content),
        trailing: Text(
          DateFormat('HH:mm').format(notification.timestamp),
          style: TextStyle(
            color: notification.isRead ? Colors.grey : Colors.blue,
            fontWeight: notification.isRead ? FontWeight.normal : FontWeight.bold
          ),
        ),
        onTap: () => _showNotificationDetail(notification),
      ),
    );
  }
}

十四、课程证书系统

1. 证书生成模型

python

复制

# certificates/models.py
from django.db import models
from django.contrib.auth import get_user_model
from courses.models import Course

User = get_user_model()

class CourseCertificate(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    course = models.ForeignKey(Course, on_delete=models.CASCADE)
    issued_at = models.DateTimeField(auto_now_add=True)
    certificate_id = models.CharField(max_length=64, unique=True)
    verification_url = models.URLField()
    pdf_file = models.FileField(upload_to='certificates/')
    metadata = models.JSONField(default=dict)
    
    class Meta:
        unique_together = ('user', 'course')
        indexes = [
            models.Index(fields=['certificate_id']),
            models.Index(fields=['user', 'course'])
        ]

class CertificateTemplate(models.Model):
    name = models.CharField(max_length=100)
    template_file = models.FileField(upload_to='certificate_templates/')
    config = models.JSONField()
    is_active = models.BooleanField(default=True)

2. PDF 证书生成服务

python

复制

# certificates/services.py
from reportlab.lib.pagesizes import A4
from reportlab.pdfgen import canvas
from reportlab.lib.styles import ParagraphStyle
from reportlab.platypus import Paragraph
from io import BytesIO
from django.core.files import File

class CertificateGenerator:
    def __init__(self, template):
        self.template = template
        self.config = template.config

    def generate_pdf(self, user, course):
        buffer = BytesIO()
        c = canvas.Canvas(buffer, pagesize=A4)
        
        # 绘制背景模板
        c.drawImage(self.template.template_file.path, 0, 0, width=A4[0], height=A4[1])
        
        # 添加动态内容
        self._draw_text(c, self.config['title_position'], course.title)
        self._draw_text(c, self.config['student_name_position'], user.get_full_name())
        self._draw_qr_code(c, self.config['qr_code_position'], verification_url)
        
        c.save()
        buffer.seek(0)
        return File(buffer, name=f"certificate_{course.id}.pdf")

    def _draw_text(self, canvas, position, text):
        style = ParagraphStyle(
            name='cert',
            fontName='Helvetica-Bold',
            fontSize=24,
            leading=30,
            alignment=1
        )
        p = Paragraph(text, style)
        p.wrapOn(canvas, 400, 100)
        p.drawOn(canvas, position['x'], position['y'])

    def _draw_qr_code(self, canvas, position, url):
        qr = qrcode.QRCode(
            version=1,
            error_correction=qrcode.constants.ERROR_CORRECT_L,
            box_size=6,
            border=4,
        )
        qr.add_data(url)
        qr.make(fit=True)
        img = qr.make_image(fill_color="black", back_color="white")
        img_buffer = BytesIO()
        img.save(img_buffer, format='PNG')
        canvas.drawImage(img_buffer, position['x'], position['y'], width=100, height=100)

3. Flutter 证书展示

dart

复制

// lib/widgets/certificate_viewer.dart
import 'package:flutter_pdfview/flutter_pdfview.dart';

class CertificateViewer extends StatefulWidget {
  final String certificateUrl;

  const CertificateViewer({super.key, required this.certificateUrl});

  @override
  _CertificateViewerState createState() => _CertificateViewerState();
}

class _CertificateViewerState extends State {
  final Completer _controller = Completer();
  int? pages = 0;
  bool isReady = false;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('课程证书'),
        actions: [
          IconButton(
            icon: const Icon(Icons.share),
            onPressed: _shareCertificate,
          ),
        ],
      ),
      body: Stack(
        children: [
          PDFView(
            filePath: widget.certificateUrl,
            enableSwipe: true,
            swipeHorizontal: true,
            autoSpacing: false,
            pageFling: false,
            onRender: (pages) => setState(() {
              this.pages = pages;
              isReady = true;
            }),
            onViewCreated: (controller) {
              _controller.complete(controller);
            },
          ),
          if (!isReady)
            const Center(child: CircularProgressIndicator()),
        ],
      ),
      floatingActionButton: FutureBuilder(
        future: _controller.future,
        builder: (context, snapshot) {
          if (snapshot.hasData) {
            return Row(
              mainAxisAlignment: MainAxisAlignment.end,
              children: [
                IconButton(
                  icon: const Icon(Icons.zoom_in),
                  onPressed: () => snapshot.data!.setZoom(1.5),
                ),
                IconButton(
                  icon: const Icon(Icons.zoom_out),
                  onPressed: () => snapshot.data!.setZoom(1.0),
                ),
              ],
            );
          }
          return Container();
        },
      ),
    );
  }

  void _shareCertificate() async {
    final file = File(widget.certificateUrl);
    await Share.shareFiles(
      [file.path],
      text: '这是我的课程证书：${widget.certificateUrl}',
    );
  }
}

十五、系统扩展建议

AI 助教功能实现

使用 Transformer 模型构建智能问答系统
集成语音识别实现语音问答
自动生成课程摘要和知识点脑图

微服务架构改造

将用户服务、课程服务拆分为独立微服务
使用 gRPC 进行服务间通信
引入服务网格进行流量管理

区块链证书存证

将证书哈希值存储至以太坊网络
开发智能合约进行证书验证
实现去中心化的学分互认体系

虚拟现实教学

使用 Unity 开发 VR 课程内容
集成 3D 模型展示功能
开发虚拟实验室交互系统

以上实现方案涵盖了在线教育系统的完整技术栈，实际开发中需要根据具体需求进行调整。

建议优先实现核心教学功能，再逐步扩展高级功能。

每个模块都应配套完善的单元测试和端到端测试，推荐使用：

Django: pytest-django, factory-boy
Flutter: mockito, integration_test
API测试: Postman, Newman
压力测试: Locust, JMeter

系统上线后应建立完善的监控体系，推荐组合：

基础设施监控: Prometheus + Grafana
应用性能监控: Elastic APM
日志分析: ELK Stack
错误追踪: Sentry

因为平台对单篇文章的字数限制，部分内容只得省略，敬请谅解！

手把手教您使用Python+Flutter开发在线教育系统(下)，纯干货!

七、讨论区系统实现

1. 完善的评论模型设计（discussion/models.py）

2. 序列化器（discussion/serializers.py）

3. 视图（discussion/views.py）

4. 路由配置（discussion/urls.py）

5. 评论列表组件（lib/components/comment_list.dart）

6. 评论发布组件（lib/components/comment_input.dart）

7、系统功能验证

测试用例

八、推荐系统深度实现

1. 推荐系统架构

2. 用户行为日志设计

3. 混合推荐算法实现

4. 推荐API实现

九、用户个人中心完整实现

1. 用户模型扩展

2. 个人中心API

3. Flutter个人中心界面

十、教师管理后台实现

1. 教师权限管理

2. 教学数据统计API

3. Flutter教师仪表盘

十一、系统安全加固措施

1. 安全中间件配置

2. 请求频率限制

3. 敏感操作审计日志（代码简略）

十二、持续集成与自动化部署

1. GitLab CI/CD 配置

2. Docker 生产环境配置

3. 监控告警配置

十三、消息通知系统

1. 通知模型设计

2. WebSocket 通知推送

3. Flutter 消息中心实现

十四、课程证书系统

1. 证书生成模型

2. PDF 证书生成服务

3. Flutter 证书展示

十五、系统扩展建议

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