Cloudflare Workers 深度实战指南

export default {
  async fetch(request, env, ctx) {
    const url = new URL(request.url)
    const path = url.pathname

    // 路由分发
    if (path === '/api/health' && request.method === 'GET') {
      return new Response(JSON.stringify({ ok: true }), {
        headers: { 'Content-Type': 'application/json' }
      })
    }

    if (path.startsWith('/api/users/') && request.method === 'GET') {
      const userId = path.split('/')[3]
      return handleGetUser(userId, env)
    }

    return new Response('Not Found', { status: 404 })
  }
}

import { Router } from 'itty-router'

const router = Router()

router.get('/api/health', () => ({ ok: true }))

router.get('/api/users/:id', ({ params }) => {
  return { userId: params.id }
})

router.post('/api/users', async (request) => {
  const body = await request.json()
  // 处理用户创建
  return { success: true }
})

// 404 兜底
router.all('*', () => new Response('Not Found', { status: 404 }))

export default {
  fetch: router.handle
}

// 写入（带过期时间）
await env.MY_KV.put('user:123', JSON.stringify(userData), {
  expirationTtl: 3600  // 1小时后过期
})

// 读取
const data = await env.MY_KV.get('user:123', 'json')

// 删除
await env.MY_KV.delete('user:123')

// 查询
const { results } = await env.DB.prepare(
  'SELECT id, name, email FROM users WHERE id = ?'
).bind(userId).all()

// 插入
const result = await env.DB.prepare(
  'INSERT INTO users (name, email) VALUES (?, ?)'
).bind(name, email).run()

console.log('插入ID:', result.meta.last_row_id)

// 事务
await env.DB.batch([
  env.DB.prepare('UPDATE accounts SET balance = balance - ? WHERE id = ?').bind(100, fromId),
  env.DB.prepare('UPDATE accounts SET balance = balance + ? WHERE id = ?').bind(100, toId)
])

// 上传
await env.BUCKET.put('avatars/user-123.jpg', imageBuffer, {
  httpMetadata: { contentType: 'image/jpeg' }
})

// 读取
const object = await env.BUCKET.get('avatars/user-123.jpg')
if (object) {
  return new Response(object.body, {
    headers: { 'Content-Type': object.httpMetadata.contentType }
  })
}

// 删除
await env.BUCKET.delete('avatars/user-123.jpg')

// ❌ 低效：每次请求都做复杂计算
export default {
  async fetch(request) {
    const result = heavyComputation()  // 耗时5ms
    return new Response(result)
  }
}

// ✅ 高效：缓存计算结果到全局变量
let cachedResult = null
export default {
  async fetch(request) {
    if (!cachedResult) {
      cachedResult = heavyComputation()
    }
    return new Response(cachedResult)
  }
}

// ❌ 串行：总耗时 = t1 + t2 + t3
const user = await env.DB.prepare('SELECT * FROM users WHERE id = ?').bind(id).first()
const posts = await env.DB.prepare('SELECT * FROM posts WHERE user_id = ?').bind(id).all()
const comments = await env.DB.prepare('SELECT * FROM comments WHERE user_id = ?').bind(id).all()

// ✅ 并行：总耗时 = max(t1, t2, t3)
const [user, posts, comments] = await Promise.all([
  env.DB.prepare('SELECT * FROM users WHERE id = ?').bind(id).first(),
  env.DB.prepare('SELECT * FROM posts WHERE user_id = ?').bind(id).all(),
  env.DB.prepare('SELECT * FROM comments WHERE user_id = ?').bind(id).all()
])

export default {
  async fetch(request, env, ctx) {
    const cache = caches.default
    const cachedResponse = await cache.match(request)
    
    if (cachedResponse) {
      return cachedResponse
    }

    const response = await generateResponse(request)
    // 缓存1小时
    response.headers.set('Cache-Control', 's-maxage=3600')
    ctx.waitUntil(cache.put(request, response.clone()))
    return response
  }
}

const corsHeaders = {
  'Access-Control-Allow-Origin': 'https://your-domain.com',
  'Access-Control-Allow-Methods': 'GET, POST, PUT, DELETE, OPTIONS',
  'Access-Control-Allow-Headers': 'Content-Type, Authorization',
  'Access-Control-Max-Age': '86400'
}

export default {
  async fetch(request) {
    if (request.method === 'OPTIONS') {
      return new Response(null, { headers: corsHeaders })
    }

    const response = await handleRequest(request)
    Object.entries(corsHeaders).forEach(([k, v]) => {
      response.headers.set(k, v)
    })
    return response
  }
}

const RATE_LIMIT = 100  // 每分钟最多100次
const WINDOW = 60        // 时间窗口（秒）

export default {
  async fetch(request, env) {
    const ip = request.headers.get('CF-Connecting-IP')
    const key = `rate:${ip}`
    const count = parseInt(await env.RATE_KV.get(key)) || 0

    if (count >= RATE_LIMIT) {
      return new Response('Too Many Requests', { status: 429 })
    }

    await env.RATE_KV.put(key, String(count + 1), { expirationTtl: WINDOW })
    return handleRequest(request)
  }
}