单体应用的模块化开发代码例子

以下是一个使用模块化开发的单体应用的代码例子：

// app.js

// 引入模块
const express = require('express');
const bodyParser = require('body-parser');
const userRoutes = require('./routes/userRoutes');
const postRoutes = require('./routes/postRoutes');

// 初始化应用
const app = express();

// 中间件
app.use(bodyParser.json());

// 路由
app.use('/users', userRoutes);
app.use('/posts', postRoutes);

// 启动应用
app.listen(3000, () => {
  console.log('应用已启动');
});

// routes/userRoutes.js

const express = require('express');
const userController = require('../controllers/userController');

const router = express.Router();

router.get('/', userController.getAllUsers);
router.get('/:id', userController.getUserById);
router.post('/', userController.createUser);
router.put('/:id', userController.updateUser);
router.delete('/:id', userController.deleteUser);

module.exports = router;

// controllers/userController.js

const users = [];

function getAllUsers(req, res) {
  res.json(users);
}

function getUserById(req, res) {
  const userId = req.params.id;
  const user = users.find(u => u.id === userId);
  if (user) {
    res.json(user);
  } else {
    res.status(404).json({ message: '用户不存在' });
  }
}

function createUser(req, res) {
  const { name, age } = req.body;
  const newUser = { id: Date.now().toString(), name, age };
  users.push(newUser);
  res.status(201).json(newUser);
}

function updateUser(req, res) {
  const userId = req.params.id;
  const { name, age } = req.body;
  const userIndex = users.findIndex(u => u.id === userId);
  if (userIndex !== -1) {
    users[userIndex] = { ...users[userIndex], name, age };
    res.json(users[userIndex]);
  } else {
    res.status(404).json({ message: '用户不存在' });
  }
}

function deleteUser(req, res) {
  const userId = req.params.id;
  const userIndex = users.findIndex(u => u.id === userId);
  if (userIndex !== -1) {
    users.splice(userIndex, 1);
    res.json({ message: '删除成功' });
  } else {
    res.status(404).json({ message: '用户不存在' });
  }
}

module.exports = {
  getAllUsers,
  getUserById,
  createUser,
  updateUser,
  deleteUser,
};

// routes/postRoutes.js

const express = require('express');
const postController = require('../controllers/postController');

const router = express.Router();

router.get('/', postController.getAllPosts);
router.get('/:id', postController.getPostById);
router.post('/', postController.createPost);
router.put('/:id', postController.updatePost);
router.delete('/:id', postController.deletePost);

module.exports = router;

// controllers/postController.js

const posts = [];

function getAllPosts(req, res) {
  res.json(posts);
}

function getPostById(req, res) {
  const postId = req.params.id;
  const post = posts.find(p => p.id === postId);
  if (post) {
    res.json(post);
  } else {
    res.status(404).json({ message: '文章不存在' });
  }
}

function createPost(req, res) {
  const { title, content } = req.body;
  const newPost = { id: Date.now().toString(), title, content };
  posts.push(newPost);
  res.status(201).json(newPost);
}

function updatePost(req, res) {
  const postId = req.params.id;
  const { title, content } = req.body;
  const postIndex = posts.findIndex(p => p.id === postId);
  if (postIndex !== -1) {
    posts[postIndex] = { ...posts[postIndex], title, content };
    res.json(posts[postIndex]);
  } else {
    res.status(404).json({ message: '文章不存在' });
  }
}

function deletePost(req, res) {
  const postId = req.params.id;
  const postIndex = posts.findIndex(p => p.id === postId);
  if (postIndex !== -1) {
    posts.splice(postIndex, 1);
    res.json({ message: '删除成功' });
  } else {
    res.status(404).json({ message: '文章不存在' });
  }
}

module.exports = {
  getAllPosts,
  getPostById,
  createPost,
  updatePost,
  deletePost,
};

在以上例子中，我们将应用拆分成了多个模块，每个模块都有自己的路由和控制器，使得代码更加清晰和易于维护。通过在 app.js 中引入模块，我们可以将模块组合起来形成一个完整的应用。