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app.js

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+require('dotenv').config();
+const express = require('express');
+const mongoose = require('mongoose');
+const cors = require('cors');
+const morgan = require('morgan');
+
+// 导入路由
+const authRoutes = require('./routes/auth');
+const examRoutes = require('./routes/exams');
+const resultRoutes = require('./routes/results');
+
+// 初始化应用
+const app = express();
+
+// 中间件
+app.use(cors());
+app.use(morgan('dev'));
+app.use(express.json());
+
+// 数据库连接
+mongoose.connect(process.env.MONGODB_URI)
+    .then(() => console.log('Connected to MongoDB'))
+    .catch(err => console.error('MongoDB connection error:', err));
+
+// 路由
+app.use('/api/auth', authRoutes);
+app.use('/api/exams', examRoutes);
+app.use('/api/results', resultRoutes);
+
+// 错误处理中间件
+app.use((err, req, res, next) => {
+    console.error(err.stack);
+    res.status(500).json({ message: 'Something went wrong!' });
+});
+
+// 启动服务器
+const PORT = process.env.PORT || 5000;
+app.listen(PORT, () => {
+    console.log(`Server running on port ${PORT}`);
+});
+// 在app.js中添加更详细的CORS配置
+app.use(cors({
+    origin: 'http://localhost', // 或你的前端实际域名
+    methods: ['GET', 'POST', 'PUT', 'DELETE'],
+    allowedHeaders: ['Content-Type', 'Authorization']
+}));