面试题手册

Deno 的模块系统采用去中心化的设计，与 Node.js 的 npm 生态系统有显著不同。理解 Deno 的模块导入机制对于高效开发至关重要。模块导入方式1. URL 导入Deno 使用 URL 直接导入模块，这是其最显著的特点：// 从 Deno 标准库导入import { serve } from "https://deno.land/std@0.208.0/http/server.ts";// 从第三方库导入import { oak } from "https://deno.land/x/oak@v12.6.1/mod.ts";// 从 GitHub 导入import { myLib } from "https://raw.githubusercontent.com/user/repo/main/mod.ts";2. 本地文件导入// 相对路径导入import { utils } from "./utils.ts";import { helper } from "../helper/helper.ts";// 绝对路径导入import { config } from "/app/config.ts";3. 导入映射（Import Maps）使用 import_map.json 管理模块别名：{ "imports": { "std/": "https://deno.land/std@0.208.0/", "oak": "https://deno.land/x/oak@v12.6.1/mod.ts", "@utils/": "./src/utils/" }}使用方式：import { serve } from "std/http/server.ts";import { Application } from "oak";import { formatDate } from "@utils/date.ts";运行时指定 import map：deno run --import-map=import_map.json app.ts版本管理1. 版本锁定Deno 推荐在 URL 中指定具体版本：// 推荐：指定版本import { serve } from "https://deno.land/std@0.208.0/http/server.ts";// 不推荐：使用最新版本（可能不稳定）import { serve } from "https://deno.land/std/http/server.ts";2. 依赖缓存Deno 会缓存所有下载的模块：# 查看缓存位置deno info# 重新下载依赖deno cache --reload app.ts# 清除缓存deno cache --reload all模块导出1. 命名导出// utils.tsexport const add = (a: number, b: number): number => a + b;export const subtract = (a: number, b: number): number => a - b;export interface User { id: number; name: string;}2. 默认导出// app.tsexport default class Application { start() { console.log("Application started"); }}3. 重新导出// index.tsexport * from "./utils.ts";export { default as App } from "./app.ts";export type { User } from "./types.ts";权限要求导入远程模块时，Deno 需要网络权限：# 允许网络访问以下载模块deno run --allow-net app.ts# 允许读取缓存deno run --allow-read app.ts与 Node.js 的对比| 特性 | Deno | Node.js ||------|------|---------|| 导入方式 | URL 导入 | npm 包名 || 依赖管理 | 无 package.json | package.json + nodemodules || 版本控制 | URL 中的版本号 | package.json 版本范围 || 模块解析 | 直接 URL | nodemodules 查找算法 || 缓存机制 | 全局缓存 | 本地 node_modules || 类型支持 | 原生 TypeScript | 需要 @types 包 |最佳实践始终指定版本：在 URL 中使用明确的版本号使用 Import Maps：简化模块路径管理依赖锁定：考虑使用 deno.lock 文件权限最小化：只授予必要的权限缓存管理：定期清理和更新缓存实际示例创建一个简单的 Web 服务器：// server.tsimport { serve } from "https://deno.land/std@0.208.0/http/server.ts";const handler = async (req: Request): Promise<Response> => { const url = new URL(req.url); if (url.pathname === "/") { return new Response("Hello, Deno!", { headers: { "content-type": "text/plain" }, }); } return new Response("Not Found", { status: 404 });};await serve(handler, { port: 8000 });运行：deno run --allow-net server.tsDeno 的模块系统提供了更简单、更直接的依赖管理方式，消除了 node_modules 的复杂性，同时保持了良好的类型支持和开发体验。

Deno 的 deno compile 命令可以将 TypeScript/JavaScript 代码编译为独立的可执行文件，这使得分发和部署变得更加简单。这个功能对于创建命令行工具和独立应用程序特别有用。deno compile 概述deno compile 将 Deno 脚本及其所有依赖打包成一个单一的可执行文件，无需在目标机器上安装 Deno。基本用法1. 简单编译# 编译为可执行文件deno compile app.ts# 默认输出文件名与输入文件相同（无扩展名）# app.ts → app (Linux/Mac) 或 app.exe (Windows)2. 指定输出文件名# 指定输出文件名deno compile --output=myapp app.ts# Windowsdeno compile --output=myapp.exe app.ts3. 指定目标平台# 编译为 Linux 可执行文件deno compile --target=x86_64-unknown-linux-gnu app.ts# 编译为 macOS 可执行文件deno compile --target=x86_64-apple-darwin app.tsdeno compile --target=aarch64-apple-darwin app.ts # Apple Silicon# 编译为 Windows 可执行文件deno compile --target=x86_64-pc-windows-msvc app.ts4. 包含权限# 编译时包含权限，运行时无需再次指定deno compile --allow-net --allow-read app.ts# 包含所有权限deno compile --allow-all app.ts5. 设置环境变量# 设置编译时的环境变量deno compile --env=API_KEY=secret app.ts实际应用示例1. 命令行工具// cli.ts#!/usr/bin/env -S deno runconst name = Deno.args[0] || "World";const verbose = Deno.args.includes("--verbose");if (verbose) { console.log("Verbose mode enabled");}console.log(`Hello, ${name}!`);// 文件操作示例const filename = Deno.args[1];if (filename) { try { const content = await Deno.readTextFile(filename); console.log(`File content: ${content}`); } catch (error) { console.error(`Error reading file: ${error.message}`); }}编译：deno compile --allow-read --output=hello cli.ts./hello Deno --verbose2. Web 服务器// server.tsimport { serve } from "https://deno.land/std@0.208.0/http/server.ts";const PORT = Deno.env.get("PORT") || "8000";const handler = async (req: Request): Promise<Response> => { const url = new URL(req.url); if (url.pathname === "/") { return new Response("Hello from Deno server!", { headers: { "Content-Type": "text/plain" }, }); } if (url.pathname === "/health") { return new Response(JSON.stringify({ status: "ok" }), { headers: { "Content-Type": "application/json" }, }); } return new Response("Not Found", { status: 404 });};console.log(`Server running on port ${PORT}`);await serve(handler, { port: parseInt(PORT) });编译：deno compile --allow-net --allow-env --output=server server.ts./server3. 文件处理工具// file-processor.tsimport { walk } from "https://deno.land/std@0.208.0/fs/walk.ts";const directory = Deno.args[0] || ".";const pattern = Deno.args[1];console.log(`Scanning directory: ${directory}`);if (pattern) { console.log(`Pattern: ${pattern}`);}let count = 0;for await (const entry of walk(directory)) { if (entry.isFile) { if (!pattern || entry.name.includes(pattern)) { console.log(`Found: ${entry.path}`); count++; } }}console.log(`Total files found: ${count}`);编译：deno compile --allow-read --output=scan file-processor.ts./scan ./src .ts4. API 客户端// api-client.tsconst API_URL = Deno.env.get("API_URL") || "https://api.example.com";const API_KEY = Deno.env.get("API_KEY");if (!API_KEY) { console.error("API_KEY environment variable is required"); Deno.exit(1);}async function fetchData(endpoint: string): Promise<any> { const response = await fetch(`${API_URL}${endpoint}`, { headers: { "Authorization": `Bearer ${API_KEY}`, "Content-Type": "application/json", }, }); if (!response.ok) { throw new Error(`API request failed: ${response.status}`); } return response.json();}const endpoint = Deno.args[0] || "/users";console.log(`Fetching data from: ${API_URL}${endpoint}`);try { const data = await fetchData(endpoint); console.log(JSON.stringify(data, null, 2));} catch (error) { console.error(`Error: ${error.message}`); Deno.exit(1);}编译：deno compile --allow-net --allow-env --output=api-client api-client.tsAPI_KEY=your_key ./api-client /users高级用法1. 交叉编译在 macOS 上编译 Linux 可执行文件：deno compile --target=x86_64-unknown-linux-gnu --output=myapp-linux app.ts2. 压缩可执行文件使用 upx 压缩编译后的可执行文件：# 安装 upxbrew install upx # macOSapt install upx # Linux# 压缩upx --best myapp3. 创建图标（仅限 Windows）# 为 Windows 可执行文件添加图标deno compile --icon=icon.ico --output=myapp.exe app.ts4. 设置元数据# 设置可执行文件元数据deno compile \ --output=myapp \ --app-name="My Application" \ --app-version="1.0.0" \ app.ts部署场景1. Docker 部署# 多阶段构建FROM denoland/deno:1.38.0 AS builderWORKDIR /appCOPY . .RUN deno compile --allow-net --allow-read --output=app server.tsFROM debian:bullseye-slimWORKDIR /appCOPY --from=builder /app/app .EXPOSE 8000CMD ["./app"]2. 云函数部署// cloud-function.tsexport async function handler(event: any): Promise<any> { const name = event.name || "World"; return { statusCode: 200, body: JSON.stringify({ message: `Hello, ${name}!` }), };}编译：deno compile --output=handler cloud-function.ts3. 独立应用分发# 为不同平台编译deno compile --target=x86_64-unknown-linux-gnu --output=myapp-linux app.tsdeno compile --target=x86_64-apple-darwin --output=myapp-macos app.tsdeno compile --target=x86_64-pc-windows-msvc --output=myapp-windows.exe app.ts# 创建发布包mkdir releasecp myapp-linux release/cp myapp-macos release/cp myapp-windows.exe release/限制和注意事项1. 文件大小编译后的可执行文件通常较大（约 50-100 MB），因为包含了整个 Deno 运行时和 V8 引擎。2. 动态导入动态导入的模块会在运行时下载，不会被包含在可执行文件中：// 这个模块不会被打包const module = await import("https://example.com/module.ts");3. 原生模块使用 FFI 的原生模块需要确保目标平台上有相应的库。4. 权限编译时指定的权限在运行时生效，无法在运行时更改。最佳实践指定目标平台：明确指定编译目标，避免兼容性问题最小权限：只授予必要的权限测试编译结果：在目标平台上测试可执行文件版本控制：记录编译命令和 Deno 版本文档化：在 README 中说明如何编译和运行使用 CI/CD：自动化编译和发布流程与其他工具对比| 特性 | deno compile | pkg | nexe ||------|--------------|-----|------|| 原生支持 | 是 | 否 | 否 || 跨平台 | 是 | 是 | 是 || 文件大小 | 较大 | 中等 | 中等 || 性能 | 好 | 好 | 好 || 维护性 | 官方支持 | 社区维护 | 社区维护 |故障排查1. 编译失败# 查看详细错误信息deno compile --log-level=debug app.ts2. 运行时错误# 检查权限deno compile --allow-net --allow-read app.ts# 检查环境变量API_KEY=secret ./app3. 兼容性问题# 检查目标平台deno compile --target=x86_64-unknown-linux-gnu app.ts# 使用 Docker 测试docker run --rm -v $(pwd):/app debian:bullseye-slim ./appdeno compile 为 Deno 应用程序提供了简单而强大的分发方式，特别适合需要独立部署的场景。通过合理使用这个功能，可以大大简化应用程序的部署和分发流程。

Deno 的生态系统虽然相对年轻，但发展迅速，提供了丰富的第三方库和工具。了解 Deno 的生态系统有助于开发者更好地利用现有资源。生态系统概述Deno 的生态系统主要由以下几个部分组成：deno.land/x - 第三方模块注册表deno.land/std - 官方标准库nest.land - 另一个流行的模块注册表Deno Deploy - 官方边缘计算平台社区工具和框架 - 各种开发工具和框架流行的第三方库1. Web 框架Oakimport { Application, Router } from "https://deno.land/x/oak@v12.6.1/mod.ts";const app = new Application();const router = new Router();router.get("/", (ctx) => { ctx.response.body = "Hello, Oak!";});router.get("/users/:id", (ctx) => { const { id } = ctx.params; ctx.response.body = { id, name: `User ${id}` };});app.use(router.routes());app.use(router.allowedMethods());await app.listen({ port: 8000 });Freshimport { Fresh } from "https://deno.land/x/fresh@1.4.0/server.ts";import { handler } from "./routes/index.tsx";const app = new Fresh();app.get("/", handler);await app.listen({ port: 8000 });Honoimport { Hono } from "https://deno.land/x/hono@v3.11.0/mod.ts";const app = new Hono();app.get("/", (c) => c.text("Hello, Hono!"));app.get("/users/:id", (c) => { const id = c.req.param("id"); return c.json({ id, name: `User ${id}` });});Deno.serve(app.fetch);2. 数据库客户端PostgreSQL (postgres)import { Client } from "https://deno.land/x/postgres@v0.17.0/mod.ts";const client = new Client({ user: "user", database: "database", hostname: "localhost", port: 5432, password: "password",});await client.connect();const result = await client.queryArray("SELECT * FROM users");console.log(result.rows);await client.end();MySQL (mysql)import { Client } from "https://deno.land/x/mysql@v2.12.0/mod.ts";const client = await new Client().connect({ hostname: "127.0.0.1", username: "root", password: "password", db: "test",});const users = await client.query("SELECT * FROM users");console.log(users);await client.close();MongoDB (mongo)import { MongoClient } from "https://deno.land/x/mongo@v0.31.0/mod.ts";const client = new MongoClient();await client.connect("mongodb://localhost:27017");const db = client.database("test");const users = db.collection<User>("users");const user = await users.findOne({ name: "John" });console.log(user);await client.close();Redis (redis)import { connect } from "https://deno.land/x/redis@v0.31.0/mod.ts";const redis = await connect({ hostname: "127.0.0.1", port: 6379,});await redis.set("key", "value");const value = await redis.get("key");console.log(value);await redis.close();3. ORM 和查询构建器DenoDBimport { Database } from "https://deno.land/x/denodb@v1.0.0/mod.ts";const db = new Database("postgres", { host: "127.0.0.1", username: "user", password: "password", database: "test",});class User extends Model { static fields = { id: { primaryKey: true, autoIncrement: true }, name: { type: VARCHAR }, email: { type: VARCHAR, unique: true }, };}db.link([User]);await db.sync();const user = await User.create({ name: "John", email: "john@example.com" });console.log(user);Drizzle ORMimport { drizzle } from "https://deno.land/x/drizzle@v0.5.0/mod.ts";import { pgTable, serial, text, varchar } from "https://deno.land/x/drizzle@v0.5.0/pg-core/mod.ts";const users = pgTable("users", { id: serial("id").primaryKey(), name: text("name").notNull(), email: varchar("email", { length: 255 }).notNull().unique(),});const db = drizzle("postgresql://user:password@localhost:5432/test");const user = await db.insert(users).values({ name: "John", email: "john@example.com",}).returning().get();console.log(user);4. 认证和授权JWT (djwt)import { create, verify, getNumericDate } from "https://deno.land/x/djwt@v3.0.1/mod.ts";const key = await crypto.subtle.generateKey( { name: "HMAC", hash: "SHA-256" }, true, ["sign", "verify"]);const payload = { iss: "my-app", exp: getNumericDate(60 * 60), // 1 hour data: { userId: 123 },};const token = await create({ alg: "HS256", typ: "JWT" }, payload, key);console.log("Token:", token);const verified = await verify(token, key);console.log("Verified:", verified);OAuth (oauth2_client)import { OAuth2Client } from "https://deno.land/x/oauth2_client@v1.0.2/mod.ts";const oauth2Client = new OAuth2Client({ clientId: "your-client-id", clientSecret: "your-client-secret", authorizationEndpointUri: "https://github.com/login/oauth/authorize", tokenUri: "https://github.com/login/oauth/access_token",});const authUrl = oauth2Client.code.getAuthorizationUri({ redirectUri: "http://localhost:8000/callback", scope: "read:user",});console.log("Visit:", authUrl);5. 工具库Lodash (lodash)import _ from "https://deno.land/x/lodash@4.17.19-es/mod.ts";const users = [ { name: "John", age: 30 }, { name: "Jane", age: 25 },];const sorted = _.orderBy(users, ["age"], ["asc"]);console.log(sorted);const names = _.map(users, "name");console.log(names);Date-fns (date_fns)import { format, addDays, isAfter } from "https://deno.land/x/date_fns@v2.29.3/mod.ts";const now = new Date();const future = addDays(now, 7);console.log(format(now, "yyyy-MM-dd"));console.log(format(future, "yyyy-MM-dd"));console.log(isAfter(future, now));Zod (zod)import { z } from "https://deno.land/x/zod@v3.21.4/mod.ts";const UserSchema = z.object({ id: z.number(), name: z.string().min(2), email: z.string().email(), age: z.number().min(0).max(120),});const userData = { id: 1, name: "John", email: "john@example.com", age: 30,};const user = UserSchema.parse(userData);console.log(user);6. 测试工具Supabase (supabase)import { createClient } from "https://deno.land/x/supabase@2.0.0/mod.ts";const supabase = createClient( "your-project-url", "your-anon-key");const { data, error } = await supabase .from("users") .select("*") .eq("id", 1);console.log(data);开发工具1. 代码格式化Deno 内置了格式化工具：deno fmt .2. 代码检查deno lint .3. 文档生成deno doc --html --output=./docs ./src4. 依赖检查deno info包管理工具1. Denoify将 Node.js 包转换为 Deno 兼容的包：denoify2. Deno 2 NPM (d2n)将 npm 包转换为 Deno 模块：d2n express3. Import Map Generator自动生成 import map：deno run --allow-read --allow-write https://deno.land/x/import_map_generator/main.ts部署平台1. Deno Deploy官方边缘计算平台：// main.tsimport { serve } from "https://deno.land/std@0.208.0/http/server.ts";serve((req) => { return new Response("Hello from Deno Deploy!");});2. Vercel支持 Deno 部署：{ "builds": [ { "src": "main.ts", "use": "@vercel/deno" } ]}3. Railway支持 Deno 部署：[build]builder = "NIXPACKS"[deploy]startCommand = "deno run --allow-net main.ts"社区资源1. 官方资源官方网站: https://deno.land文档: https://deno.land/manual标准库: https://deno.land/std第三方库: https://deno.land/x2. 社区论坛GitHub Discussions: https://github.com/denoland/deno/discussionsDiscord: https://discord.gg/denoTwitter: @deno_land3. 学习资源Deno by Example: https://examples.deno.landDeno Tutorial: https://deno-tutorial.comAwesome Deno: https://github.com/denolib/awesome-deno最佳实践1. 选择合适的库优先使用标准库选择活跃维护的第三方库查看库的文档和示例检查库的更新频率2. 版本管理// 指定具体版本import { serve } from "https://deno.land/std@0.208.0/http/server.ts";import { Application } from "https://deno.land/x/oak@v12.6.1/mod.ts";3. 安全性检查库的安全性使用最小权限原则定期更新依赖4. 性能选择性能优化的库避免不必要的依赖使用缓存策略迁移指南1. 从 Node.js 迁移// Node.jsconst express = require('express');const app = express();// Denoimport { Application } from "https://deno.land/x/oak@v12.6.1/mod.ts";const app = new Application();2. 使用兼容层import { polyfill } from "https://deno.land/x/node_polyfills@v0.1.48/main.ts";polyfill();// 现在可以使用 Node.js APIconst fs = require('fs');未来发展Deno 生态系统正在快速发展，以下是一些值得关注的趋势：更多第三方库：生态系统持续扩大更好的工具支持：开发工具不断完善企业级功能：更多企业级特性性能优化：持续的性能改进跨平台支持：更好的跨平台兼容性Deno 的生态系统虽然年轻，但发展迅速，提供了丰富的资源和工具。通过合理利用这些资源，开发者可以更高效地构建应用程序。

Expo CLI和Expo Go是Expo开发流程中的两个核心工具，它们各自承担不同的职责，协同工作以提供高效的开发体验。Expo CLI：Expo CLI是命令行工具，用于创建、构建和管理Expo项目。主要功能：项目初始化：通过npx create-expo-app命令快速创建新的Expo项目，支持TypeScript、JavaScript等多种模板。开发服务器：启动开发服务器，实时编译代码并提供热重载功能。构建配置：配置和管理项目的构建设置，包括应用图标、启动画面、权限配置等。打包发布：支持构建APK、IPA等安装包，或直接发布到Expo服务器。依赖管理：安装和更新Expo SDK版本及依赖包。常用命令：npx create-expo-app my-appnpx expo startnpx expo build:androidnpx expo build:iosExpo Go：Expo Go是一个移动应用，可在Android和iOS设备上安装，用于实时预览和测试Expo应用。主要功能：实时预览：通过扫描二维码或输入URL，在真实设备上查看应用效果。无需构建：开发过程中无需编译原生代码，大幅提升开发效率。跨设备测试：同时在多台设备上测试应用，验证不同屏幕尺寸和系统版本的兼容性。内置SDK：包含完整的Expo SDK，支持所有Expo组件和API。工作流程：使用Expo CLI创建项目并启动开发服务器在移动设备上安装Expo Go应用通过Expo Go连接到开发服务器实时查看代码修改效果限制：Expo Go不支持自定义原生代码，如果项目需要添加自定义原生模块，需要使用Expo Development Build或Eject流程。最佳实践：开发阶段优先使用Expo Go进行快速迭代测试阶段使用Development Build获得更接近生产环境的表现生产构建使用EAS Build生成优化的安装包这两个工具的结合使得Expo开发流程既快速又灵活，适合从原型到生产的完整开发周期。

ERC-20是以太坊上最广泛使用的代币标准，定义了同质化代币的接口规范。以下是ERC-20标准的详细解析：ERC-20标准概述ERC-20代表"Ethereum Request for Comments 20"，由Fabian Vogelsteller于2015年提出。它定义了一套标准接口，使不同代币能够在以太坊生态系统中互操作。必须实现的方法1. totalSupply()返回代币的总供应量。function totalSupply() external view returns (uint256) { return _totalSupply;}2. balanceOf(address account)返回指定账户的代币余额。function balanceOf(address account) external view returns (uint256) { return _balances[account];}3. transfer(address recipient, uint256 amount)从调用者账户转移代币到接收者账户。function transfer(address recipient, uint256 amount) external returns (bool) { _transfer(_msgSender(), recipient, amount); return true;}4. allowance(address owner, address spender)返回授权给spender的代币数量。function allowance(address owner, address spender) external view returns (uint256) { return _allowances[owner][spender];}5. approve(address spender, uint256 amount)授权spender使用调用者的代币。function approve(address spender, uint256 amount) external returns (bool) { _approve(_msgSender(), spender, amount); return true;}6. transferFrom(address sender, address recipient, uint256 amount)使用授权额度从sender账户转移代币到recipient账户。function transferFrom(address sender, address recipient, uint256 amount) external returns (bool) { _transfer(sender, recipient, amount); uint256 currentAllowance = _allowances[sender][_msgSender()]; require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance"); unchecked { _approve(sender, _msgSender(), currentAllowance - amount); } return true;}可选实现的方法1. name()返回代币名称。function name() external view returns (string memory) { return _name;}2. symbol()返回代币符号。function symbol() external view returns (string memory) { return _symbol;}3. decimals()返回代币的小数位数，通常为18。function decimals() external view returns (uint8) { return _decimals;}事件（Events）1. Transfer代币转移时触发。event Transfer(address indexed from, address indexed to, uint256 value);2. Approval授权时触发。event Approval(address indexed owner, address indexed spender, uint256 value);完整的ERC-20实现示例// SPDX-License-Identifier: MITpragma solidity ^0.8.0;contract MyToken { string private _name; string private _symbol; uint8 private _decimals; uint256 private _totalSupply; mapping(address => uint256) private _balances; mapping(address => mapping(address => uint256)) private _allowances; constructor(string memory name_, string memory symbol_, uint256 initialSupply) { _name = name_; _symbol = symbol_; _decimals = 18; _totalSupply = initialSupply; _balances[msg.sender] = initialSupply; emit Transfer(address(0), msg.sender, initialSupply); } function name() external view returns (string memory) { return _name; } function symbol() external view returns (string memory) { return _symbol; } function decimals() external view returns (uint8) { return _decimals; } function totalSupply() external view returns (uint256) { return _totalSupply; } function balanceOf(address account) external view returns (uint256) { return _balances[account]; } function transfer(address recipient, uint256 amount) external returns (bool) { _transfer(msg.sender, recipient, amount); return true; } function allowance(address owner, address spender) external view returns (uint256) { return _allowances[owner][spender]; } function approve(address spender, uint256 amount) external returns (bool) { _approve(msg.sender, spender, amount); return true; } function transferFrom(address sender, address recipient, uint256 amount) external returns (bool) { _transfer(sender, recipient, amount); uint256 currentAllowance = _allowances[sender][msg.sender]; require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance"); unchecked { _approve(sender, msg.sender, currentAllowance - amount); } return true; } function _transfer(address sender, address recipient, uint256 amount) internal { require(sender != address(0), "ERC20: transfer from the zero address"); require(recipient != address(0), "ERC20: transfer to the zero address"); uint256 senderBalance = _balances[sender]; require(senderBalance >= amount, "ERC20: transfer amount exceeds balance"); unchecked { _balances[sender] = senderBalance - amount; _balances[recipient] += amount; } emit Transfer(sender, recipient, amount); } function _approve(address owner, address spender, uint256 amount) internal { require(owner != address(0), "ERC20: approve from the zero address"); require(spender != address(0), "ERC20: approve to the zero address"); _allowances[owner][spender] = amount; emit Approval(owner, spender, amount); }}使用OpenZeppelin库OpenZeppelin提供了经过审计的ERC-20实现，推荐在生产环境中使用。// SPDX-License-Identifier: MITpragma solidity ^0.8.0;import "@openzeppelin/contracts/token/ERC20/ERC20.sol";import "@openzeppelin/contracts/access/Ownable.sol";contract MyToken is ERC20, Ownable { constructor(uint256 initialSupply) ERC20("My Token", "MTK") { _mint(msg.sender, initialSupply); } function mint(address to, uint256 amount) public onlyOwner { _mint(to, amount); }}ERC-20的应用场景1. 去中心化金融（DeFi）流动性提供借贷协议衍生品交易2. 治理代币DAO投票协议治理社区激励3. 稳定币USDT、USDC、DAI法币抵押算法稳定4. 实用代币平台访问权限服务支付奖励机制ERC-20的局限性1. 授权机制问题需要两次交易（approve + transferFrom）可能导致授权额度泄露2. 缺乏批量操作每次转移都需要单独交易Gas成本较高3. 无法处理代币回调不支持接收代币时的通知可能导致代币丢失其他ERC代币标准ERC-721非同质化代币（NFT）标准，每个代币都是唯一的。ERC-1155多代币标准，支持同质化和非同质化代币。ERC-777改进的ERC-20标准，支持代币回调和批量操作。ERC-4626金库代币标准，用于DeFi收益聚合器。最佳实践使用OpenZeppelin库：避免重复造轮子，使用经过审计的代码添加访问控制：实现适当的权限管理事件日志：记录所有重要操作安全审计：在部署前进行专业审计测试覆盖：确保充分的测试覆盖率ERC-20标准是以太坊生态系统的基础，理解其工作原理对于开发区块链应用至关重要。

ELK Stack 是由 Elasticsearch、Logstash 和 Kibana 三个开源项目组成的完整日志分析平台。它们各自承担不同的职责，协同工作实现日志的收集、处理、存储和可视化。ELK Stack 组件1. Elasticsearch角色：搜索引擎和数据存储主要功能：分布式、RESTful 风格的搜索和数据分析引擎存储和索引大量数据提供强大的全文搜索能力支持复杂的数据聚合和分析特点：高性能、可扩展近实时搜索支持多种数据类型提供 RESTful API2. Logstash角色：数据收集和处理管道主要功能：从多种数据源收集数据解析、过滤和转换数据将处理后的数据发送到目标系统特点：丰富的插件生态系统灵活的数据处理能力支持实时数据处理可扩展的架构3. Kibana角色：数据可视化和分析平台主要功能：创建各种图表和仪表板数据探索和分析日志搜索和过滤报告生成和导出特点：直观的用户界面丰富的可视化选项支持实时数据展示可定制的仪表板ELK Stack 工作流程数据源 → Logstash → Elasticsearch → Kibana ↓ 数据处理详细流程数据采集Logstash 从各种数据源（文件、数据库、消息队列等）采集数据也可以使用 Beats（Filebeat、Metricbeat 等）轻量级采集器数据处理Logstash 对采集的数据进行解析、过滤和转换使用 Grok、Mutate、Date 等过滤器处理数据数据存储处理后的数据发送到 Elasticsearch 进行索引和存储Elasticsearch 提供高效的搜索和检索能力数据可视化Kibana 从 Elasticsearch 读取数据创建图表、仪表板进行数据展示和分析实际应用场景1. 日志管理应用服务器 → Filebeat → Logstash → Elasticsearch → Kibana收集应用服务器日志解析和结构化日志数据存储和搜索日志可视化日志分析2. 系统监控服务器 → Metricbeat → Logstash → Elasticsearch → Kibana收集系统指标（CPU、内存、磁盘等）聚合和分析监控数据创建监控仪表板设置告警规则3. 安全分析防火墙/IDS → Packetbeat → Logstash → Elasticsearch → Kibana收集安全事件数据分析安全威胁可视化安全态势生成安全报告Logstash 在 ELK Stack 中的作用1. 数据转换将非结构化日志转换为结构化数据统一不同格式的日志丰富数据内容（添加地理位置、用户代理信息等）2. 数据过滤过滤不需要的日志提取关键字段数据清洗和去重3. 数据路由根据日志类型路由到不同的索引将错误日志发送到专门的存储支持多输出目标4. 数据缓冲使用消息队列（Kafka、Redis）作为缓冲处理突发流量提高系统稳定性ELK Stack 优势1. 开源免费所有组件都是开源的活跃的社区支持丰富的文档和教程2. 高度可扩展支持水平扩展处理大规模数据适应业务增长3. 灵活可定制丰富的插件和配置选项支持自定义开发适应各种业务场景4. 实时处理近实时的数据处理和展示快速响应业务需求支持实时监控和告警替代方案1. EFK Stack使用 Fluentd 替代 LogstashFluentd 更轻量级适合 Kubernetes 环境2. ELKB Stack添加 Beats 组件Beats 更轻量级的数据采集适合边缘节点部署3. 商业方案SplunkDatadogSumo Logic最佳实践合理规划架构：根据业务需求选择合适的组件和配置监控和告警：建立完善的监控和告警机制数据生命周期管理：合理设置数据保留策略安全配置：启用 SSL/TLS，配置访问控制性能优化：根据数据量调整配置参数

Deno 的部署和运维是构建生产级应用的重要环节。了解如何正确部署和运维 Deno 应用程序可以确保应用的稳定性和可维护性。部署概述Deno 应用可以部署到多种环境，包括传统服务器、容器化平台、云服务和边缘计算平台。Docker 部署1. 基础 Dockerfile# 使用官方 Deno 镜像FROM denoland/deno:1.38.0# 设置工作目录WORKDIR /app# 复制依赖文件COPY deno.json ./# 缓存依赖RUN deno cache src/main.ts# 复制源代码COPY . .# 暴露端口EXPOSE 8000# 运行应用CMD ["deno", "run", "--allow-net", "--allow-env", "src/main.ts"]2. 多阶段构建# 构建阶段FROM denoland/deno:1.38.0 AS builderWORKDIR /appCOPY . .# 编译为可执行文件RUN deno compile --allow-net --allow-env --output=app src/main.ts# 运行阶段FROM debian:bullseye-slimWORKDIR /app# 从构建阶段复制可执行文件COPY --from=builder /app/app .# 暴露端口EXPOSE 8000# 运行应用CMD ["./app"]3. 生产环境 Dockerfile# 构建阶段FROM denoland/deno:1.38.0 AS builderWORKDIR /app# 安装依赖COPY deno.json ./RUN deno cache src/main.ts# 复制源代码COPY . .# 运行测试RUN deno test --allow-all# 编译为可执行文件RUN deno compile \ --allow-net \ --allow-env \ --allow-read \ --output=app \ src/main.ts# 运行阶段FROM debian:bullseye-slimWORKDIR /app# 安装必要的运行时依赖RUN apt-get update && \ apt-get install -y ca-certificates && \ rm -rf /var/lib/apt/lists/*# 创建非 root 用户RUN useradd -m -u 1000 deno# 从构建阶段复制可执行文件COPY --from=builder /app/app .# 更改所有者RUN chown -R deno:deno /app# 切换到非 root 用户USER deno# 暴露端口EXPOSE 8000# 健康检查HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \ CMD curl -f http://localhost:8000/health || exit 1# 运行应用CMD ["./app"]Kubernetes 部署1. Deployment 配置apiVersion: apps/v1kind: Deploymentmetadata: name: deno-app labels: app: deno-appspec: replicas: 3 selector: matchLabels: app: deno-app template: metadata: labels: app: deno-app spec: containers: - name: deno-app image: your-registry/deno-app:latest ports: - containerPort: 8000 env: - name: PORT value: "8000" - name: DATABASE_URL valueFrom: secretKeyRef: name: app-secrets key: database-url resources: requests: memory: "128Mi" cpu: "100m" limits: memory: "512Mi" cpu: "500m" livenessProbe: httpGet: path: /health port: 8000 initialDelaySeconds: 30 periodSeconds: 10 readinessProbe: httpGet: path: /ready port: 8000 initialDelaySeconds: 5 periodSeconds: 52. Service 配置apiVersion: v1kind: Servicemetadata: name: deno-app-servicespec: selector: app: deno-app ports: - protocol: TCP port: 80 targetPort: 8000 type: LoadBalancer3. ConfigMap 和 Secret# ConfigMapapiVersion: v1kind: ConfigMapmetadata: name: app-configdata: PORT: "8000" LOG_LEVEL: "info"---# SecretapiVersion: v1kind: Secretmetadata: name: app-secretstype: Opaquedata: database-url: <base64-encoded-url> api-key: <base64-encoded-key>云平台部署1. Deno DeployDeno Deploy 是 Deno 官方的边缘计算平台。// main.tsimport { serve } from "https://deno.land/std@0.208.0/http/server.ts";const handler = async (req: Request): Promise<Response> => { const url = new URL(req.url); if (url.pathname === "/") { return new Response("Hello from Deno Deploy!", { headers: { "Content-Type": "text/plain" }, }); } return new Response("Not Found", { status: 404 });};await serve(handler, { port: 8000 });部署步骤：创建 Deno Deploy 账户连接 GitHub 仓库配置部署设置自动部署2. Vercel 部署// vercel.json{ "version": 2, "builds": [ { "src": "src/main.ts", "use": "@vercel/deno" } ], "routes": [ { "src": "/(.*)", "dest": "/src/main.ts" } ]}3. Railway 部署# railway.toml[build]builder = "NIXPACKS"[deploy]startCommand = "deno run --allow-net --allow-env src/main.ts"[env]PORT = "8000"进程管理1. 使用 PM2// ecosystem.config.jsmodule.exports = { apps: [{ name: 'deno-app', script: 'deno', args: 'run --allow-net --allow-env src/main.ts', instances: 'max', exec_mode: 'cluster', autorestart: true, watch: false, max_memory_restart: '1G', env: { NODE_ENV: 'production', PORT: 8000 } }]};# 安装 PM2npm install -g pm2# 启动应用pm2 start ecosystem.config.js# 查看状态pm2 status# 查看日志pm2 logs# 重启应用pm2 restart deno-app# 停止应用pm2 stop deno-app2. 使用 Systemd# /etc/systemd/system/deno-app.service[Unit]Description=Deno ApplicationAfter=network.target[Service]Type=simpleUser=denoWorkingDirectory=/appEnvironment="PORT=8000"Environment="DATABASE_URL=postgres://..."ExecStart=/usr/local/bin/deno run --allow-net --allow-env /app/src/main.tsRestart=alwaysRestartSec=10[Install]WantedBy=multi-user.target# 启用服务sudo systemctl enable deno-app# 启动服务sudo systemctl start deno-app# 查看状态sudo systemctl status deno-app# 查看日志sudo journalctl -u deno-app -f# 重启服务sudo systemctl restart deno-app监控和日志1. 日志管理// logger.tsimport { getLogger, setup, handlers } from "https://deno.land/std@0.208.0/log/mod.ts";await setup({ handlers: { console: new handlers.ConsoleHandler("INFO"), file: new handlers.FileHandler("INFO", { filename: "./logs/app.log", formatter: "{levelName} {datetime} {msg}", }), }, loggers: { default: { level: "INFO", handlers: ["console", "file"], }, },});export const logger = getLogger();2. 健康检查// health.tsimport { serve } from "https://deno.land/std@0.208.0/http/server.ts";let isHealthy = true;let isReady = false;// 模拟启动时间setTimeout(() => { isReady = true;}, 5000);const handler = async (req: Request): Promise<Response> => { const url = new URL(req.url); if (url.pathname === "/health") { return new Response(JSON.stringify({ status: isHealthy ? "ok" : "error" }), { headers: { "Content-Type": "application/json" }, status: isHealthy ? 200 : 503, }); } if (url.pathname === "/ready") { return new Response(JSON.stringify({ ready: isReady }), { headers: { "Content-Type": "application/json" }, status: isReady ? 200 : 503, }); } return new Response("Not Found", { status: 404 });};await serve(handler, { port: 8000 });3. 指标收集// metrics.tsclass MetricsCollector { private metrics: Map<string, number> = new Map(); private counters: Map<string, number> = new Map(); increment(name: string, value: number = 1) { const current = this.counters.get(name) || 0; this.counters.set(name, current + value); } gauge(name: string, value: number) { this.metrics.set(name, value); } timing(name: string, duration: number) { const timings = this.metrics.get(`${name}_timings`) || []; timings.push(duration); this.metrics.set(`${name}_timings`, timings); } getMetrics(): Record<string, any> { return { counters: Object.fromEntries(this.counters), gauges: Object.fromEntries(this.metrics), }; }}export const metrics = new MetricsCollector();性能优化1. 连接池// connection-pool.tsclass ConnectionPool<T> { private pool: T[] = []; private maxConnections: number; private factory: () => Promise<T>; constructor(maxConnections: number, factory: () => Promise<T>) { this.maxConnections = maxConnections; this.factory = factory; } async acquire(): Promise<T> { if (this.pool.length > 0) { return this.pool.pop()!; } return await this.factory(); } release(connection: T) { if (this.pool.length < this.maxConnections) { this.pool.push(connection); } }}2. 缓存策略// cache.tsclass Cache { private cache: Map<string, { value: any; expires: number }> = new Map(); private ttl: number; constructor(ttl: number = 60000) { this.ttl = ttl; } set(key: string, value: any, ttl?: number) { const expires = Date.now() + (ttl || this.ttl); this.cache.set(key, { value, expires }); } get(key: string): any | null { const item = this.cache.get(key); if (!item) { return null; } if (Date.now() > item.expires) { this.cache.delete(key); return null; } return item.value; } clear() { this.cache.clear(); } cleanup() { const now = Date.now(); for (const [key, item] of this.cache.entries()) { if (now > item.expires) { this.cache.delete(key); } } }}安全最佳实践1. 环境变量管理// config.tsinterface Config { port: number; databaseUrl: string; apiKey: string; logLevel: string;}function loadConfig(): Config { const port = parseInt(Deno.env.get("PORT") || "8000"); const databaseUrl = Deno.env.get("DATABASE_URL"); const apiKey = Deno.env.get("API_KEY"); const logLevel = Deno.env.get("LOG_LEVEL") || "info"; if (!databaseUrl) { throw new Error("DATABASE_URL environment variable is required"); } if (!apiKey) { throw new Error("API_KEY environment variable is required"); } return { port, databaseUrl, apiKey, logLevel, };}export const config = loadConfig();2. 权限最小化# 只授予必要的权限deno run --allow-net --allow-env src/main.ts# 限制网络访问范围deno run --allow-net=api.example.com src/main.ts# 限制文件访问deno run --allow-read=/app/data src/main.tsCI/CD 集成1. GitHub Actions# .github/workflows/deploy.ymlname: Deployon: push: branches: [main]jobs: test: runs-on: ubuntu-latest steps: - uses: actions/checkout@v3 - name: Setup Deno uses: denoland/setup-deno@v1 with: deno-version: v1.38.0 - name: Run tests run: deno test --allow-all - name: Lint run: deno lint - name: Format check run: deno fmt --check deploy: needs: test runs-on: ubuntu-latest steps: - uses: actions/checkout@v3 - name: Build Docker image run: docker build -t deno-app:${{ github.sha }} . - name: Push to registry run: | echo ${{ secrets.REGISTRY_PASSWORD }} | docker login -u ${{ secrets.REGISTRY_USER }} --password-stdin docker push deno-app:${{ github.sha }}2. GitLab CI# .gitlab-ci.ymlstages: - test - build - deploytest: stage: test image: denoland/deno:1.38.0 script: - deno test --allow-all - deno lint - deno fmt --checkbuild: stage: build image: docker:latest services: - docker:dind script: - docker build -t deno-app:$CI_COMMIT_SHA . - docker push deno-app:$CI_COMMIT_SHAdeploy: stage: deploy image: alpine:latest script: - kubectl set image deployment/deno-app deno-app=deno-app:$CI_COMMIT_SHA only: - main故障排查1. 常见问题问题：应用启动失败# 检查日志deno run --log-level=debug src/main.ts# 检查权限deno info src/main.ts问题：内存泄漏// 定期检查内存使用setInterval(() => { const usage = Deno.memoryUsage(); console.log("Memory usage:", usage);}, 60000);问题：性能下降// 使用性能分析import { performance } from "https://deno.land/std@0.208.0/node/performance.ts";const start = performance.now();// 执行操作const duration = performance.now() - start;console.log(`Operation took ${duration}ms`);最佳实践容器化部署：使用 Docker 确保环境一致性健康检查：实现健康检查端点日志记录：记录关键操作和错误监控指标：收集和监控应用指标自动化部署：使用 CI/CD 自动化部署流程权限最小化：只授予必要的权限资源限制：设置合理的资源限制备份策略：定期备份重要数据Deno 的部署和运维需要综合考虑多个方面，通过合理的规划和实施，可以构建稳定、可靠的生产级应用。

Consul 在生产环境中的部署和运维需要考虑高可用性、性能优化、安全性和可维护性等多个方面。生产环境架构设计典型架构 ┌─────────────────┐ │ Load Balancer │ └────────┬────────┘ │ ┌────────────────────┼────────────────────┐ │ │ │ ┌────▼────┐ ┌────▼────┐ ┌────▼────┐ │ DC1 │ │ DC2 │ │ DC3 │ │ (Primary)│ │ (Backup) │ │ (Backup) │ └────┬────┘ └────┬────┘ └────┬────┘ │ │ │ ┌────▼────────────────────▼────────────────────▼────┐ │ Consul Server Cluster (3-5 nodes) │ └────────────────────────────────────────────────────┘ │ │ │ ┌────▼────┐ ┌────▼────┐ ┌────▼────┐ │ Client 1│ │ Client 2│ │ Client 3│ └─────────┘ └─────────┘ └─────────┘节点规划Server 节点数量：3-5 个奇数节点配置：高可用性、高性能部署：跨可用区分布资源：CPU 4 核、内存 8GB、磁盘 100GB SSDClient 节点数量：根据服务规模配置：轻量级部署：与应用同主机或同可用区资源：CPU 2 核、内存 4GB部署方案1. Docker 部署# docker-compose.ymlversion: '3.8'services: consul-server1: image: consul:1.15 container_name: consul-server1 hostname: consul-server1 ports: - "8500:8500" - "8600:8600/udp" volumes: - consul-data1:/consul/data command: > agent -server -bootstrap-expect=3 -ui -client=0.0.0.0 -bind=0.0.0.0 -retry-join=consul-server2 -retry-join=consul-server3 -datacenter=dc1 consul-server2: image: consul:1.15 container_name: consul-server2 hostname: consul-server2 volumes: - consul-data2:/consul/data command: > agent -server -bootstrap-expect=3 -bind=0.0.0.0 -retry-join=consul-server1 -retry-join=consul-server3 -datacenter=dc1 consul-server3: image: consul:1.15 container_name: consul-server3 hostname: consul-server3 volumes: - consul-data3:/consul/data command: > agent -server -bootstrap-expect=3 -bind=0.0.0.0 -retry-join=consul-server1 -retry-join=consul-server2 -datacenter=dc1volumes: consul-data1: consul-data2: consul-data3:2. Kubernetes 部署# consul-statefulset.yamlapiVersion: apps/v1kind: StatefulSetmetadata: name: consulspec: serviceName: consul replicas: 3 selector: matchLabels: app: consul template: metadata: labels: app: consul spec: containers: - name: consul image: consul:1.15 ports: - containerPort: 8500 name: http - containerPort: 8600 name: dns protocol: UDP env: - name: CONSUL_BIND_INTERFACE value: eth0 - name: CONSUL_GOSSIP_ENCRYPTION_KEY valueFrom: secretKeyRef: name: consul-gossip-key key: key command: - consul - agent - -server - -bootstrap-expect=3 - -ui - -client=0.0.0.0 - -data-dir=/consul/data - -retry-join=consul-0.consul.default.svc.cluster.local - -retry-join=consul-1.consul.default.svc.cluster.local - -retry-join=consul-2.consul.default.svc.cluster.local volumeMounts: - name: consul-data mountPath: /consul/data volumeClaimTemplates: - metadata: name: consul-data spec: accessModes: [ "ReadWriteOnce" ] resources: requests: storage: 10Gi3. Ansible 部署# consul.yml---- hosts: consul_servers become: yes vars: consul_version: "1.15.0" consul_datacenter: "dc1" consul_encrypt_key: "{{ vault_consul_encrypt_key }}" tasks: - name: Download Consul get_url: url: "https://releases.hashicorp.com/consul/{{ consul_version }}/consul_{{ consul_version }}_linux_amd64.zip" dest: /tmp/consul.zip - name: Install Consul unarchive: src: /tmp/consul.zip dest: /usr/local/bin remote_src: yes - name: Create Consul user user: name: consul system: yes shell: /bin/false - name: Create Consul directories file: path: "{{ item }}" state: directory owner: consul group: consul loop: - /etc/consul.d - /var/consul - name: Configure Consul template: src: consul.hcl.j2 dest: /etc/consul.d/consul.hcl owner: consul group: consul notify: restart consul - name: Create Consul systemd service copy: content: | [Unit] Description=Consul After=network.target [Service] User=consul Group=consul ExecStart=/usr/local/bin/consul agent -config-dir=/etc/consul.d [Install] WantedBy=multi-user.target dest: /etc/systemd/system/consul.service notify: restart consul - name: Start Consul systemd: name: consul state: started enabled: yes handlers: - name: restart consul systemd: name: consul state: restarted配置优化性能优化# 性能优化配置datacenter = "dc1"data_dir = "/var/consul"server = truebootstrap_expect = 3# 网络优化bind_addr = "0.0.0.0"advertise_addr = "{{ GetPrivateInterfaces | attr \"address\" }}"client_addr = "0.0.0.0"# Raft 优化raft_protocol = 3raft_multiplier = 8election_timeout = "1500ms"heartbeat_timeout = "1000ms"# Gossip 优化gossip_interval = "200ms"gossip_to_dead_time = "30s"# 快照优化snapshot_interval = "30s"snapshot_threshold = 8192# 连接优化limits { http_max_conns_per_client = 1000 rpc_max_conns_per_client = 1000}安全配置# TLS 配置verify_incoming = trueverify_outgoing = trueverify_server_hostname = trueca_file = "/etc/consul/tls/ca.crt"cert_file = "/etc/consul/tls/consul.crt"key_file = "/etc/consul/tls/consul.key"# Gossip 加密encrypt = "{{ vault_consul_encrypt_key }}"encrypt_verify_incoming = trueencrypt_verify_outgoing = true# ACL 配置acl = { enabled = true default_policy = "deny" down_policy = "extend-cache" enable_token_persistence = true tokens = { master = "{{ vault_consul_master_token }}" agent = "{{ vault_consul_agent_token }}" }}# 审计日志audit { enabled = true sink "file" { path = "/var/log/consul/audit.log" format = "json" delivery_mode = "async" }}监控和告警Prometheus 监控# prometheus.ymlscrape_configs: - job_name: 'consul' consul_sd_configs: - server: 'localhost:8500' services: ['consul'] relabel_configs: - source_labels: [__meta_consul_service_metadata_prometheus_scrape] action: keep regex: trueGrafana 仪表板{ "dashboard": { "title": "Consul Monitoring", "panels": [ { "title": "Cluster Members", "targets": [ { "expr": "consul_memberlist_member_count" } ] }, { "title": "Service Count", "targets": [ { "expr": "consul_catalog_services" } ] }, { "title": "Health Check Status", "targets": [ { "expr": "consul_health_check_status" } ] } ] }}告警规则# alerting_rules.ymlgroups: - name: consul_alerts rules: - alert: ConsulDown expr: up{job="consul"} == 0 for: 1m labels: severity: critical annotations: summary: "Consul instance down" description: "Consul instance {{ $labels.instance }} is down" - alert: ConsulLeaderMissing expr: consul_raft_leader == 0 for: 1m labels: severity: critical annotations: summary: "Consul leader missing" description: "Consul cluster has no leader" - alert: ConsulServiceUnhealthy expr: consul_health_service_status{status="passing"} == 0 for: 5m labels: severity: warning annotations: summary: "Service unhealthy" description: "Service {{ $labels.service }} is unhealthy"备份和恢复备份策略#!/bin/bash# backup_consul.shBACKUP_DIR="/backup/consul"DATE=$(date +%Y%m%d_%H%M%S)CONSUL_DIR="/var/consul"# 创建备份目录mkdir -p ${BACKUP_DIR}# 备份 Consul 数据tar -czf ${BACKUP_DIR}/consul_${DATE}.tar.gz ${CONSUL_DIR}# 备份 KV 数据consul kv export > ${BACKUP_DIR}/kv_${DATE}.json# 删除 7 天前的备份find ${BACKUP_DIR} -name "consul_*.tar.gz" -mtime +7 -deletefind ${BACKUP_DIR} -name "kv_*.json" -mtime +7 -deleteecho "Backup completed: ${BACKUP_DIR}/consul_${DATE}.tar.gz"恢复流程#!/bin/bash# restore_consul.shBACKUP_FILE=$1KV_FILE=$2if [ -z "$BACKUP_FILE" ] || [ -z "$KV_FILE" ]; then echo "Usage: $0 <backup_file> <kv_file>" exit 1fi# 停止 Consulsystemctl stop consul# 恢复数据tar -xzf ${BACKUP_FILE} -C /# 启动 Consulsystemctl start consul# 恢复 KV 数据consul kv import < ${KV_FILE}echo "Restore completed"故障排查常见问题Leader 选举失败 # 检查 Raft 状态 consul operator raft list-peers # 检查网络连接 consul members -wan服务注册失败 # 检查 Agent 状态 consul info # 检查 ACL 权限 consul acl token read -accessor <token-id>健康检查失败 # 检查健康检查状态 consul health check # 查看健康检查日志 journalctl -u consul | grep "health check"最佳实践高可用部署：至少 3 个 Server 节点，跨可用区分布定期备份：每日备份，保留 7-30 天监控告警：监控关键指标，设置合理告警阈值安全加固：启用 TLS、ACL、审计日志性能调优：根据负载调整配置参数文档完善：维护详细的运维文档和应急预案Consul 在生产环境中的稳定运行需要综合考虑架构设计、部署方案、配置优化、监控告警和故障处理等多个方面。

Expo支持Web平台，使开发者能够使用相同的代码库构建Web应用。这大大扩展了Expo的应用场景，实现了真正的跨平台开发。Expo for Web特点：单一代码库：使用相同的JavaScript/TypeScript代码响应式设计：自动适应不同屏幕尺寸Web API支持：访问浏览器原生APIPWA支持：可配置为渐进式Web应用快速开发：支持热重载和快速刷新配置Web支持：安装依赖：npx expo install react-dom react-native-web @expo/webpack-config配置app.json：{ "expo": { "web": { "bundler": "webpack", "output": "single", "favicon": "./assets/favicon.png" }, "experiments": { "typedRoutes": true } }}启动Web开发服务器：npx expo start --web平台特定代码：使用Platform模块处理平台差异：import { Platform } from 'react-native';function MyComponent() { if (Platform.OS === 'web') { return <div>Web specific content</div>; } return <View>Mobile specific content</View>;}Web特定API：窗口API：// 获取窗口尺寸const width = window.innerWidth;const height = window.innerHeight;// 监听窗口大小变化window.addEventListener('resize', handleResize);本地存储：// 使用localStoragelocalStorage.setItem('key', 'value');const value = localStorage.getItem('key');导航API：// 使用浏览器历史window.history.pushState({}, '', '/new-route');window.history.back();样式适配：响应式样式：import { StyleSheet, Dimensions } from 'react-native';const styles = StyleSheet.create({ container: { width: Dimensions.get('window').width > 768 ? '80%' : '100%', padding: 16, },});CSS媒体查询：// 使用expo-linear-gradient等库import { LinearGradient } from 'expo-linear-gradient';<LinearGradient colors={['#4c669f', '#3b5998']} style={{ flex: 1 }}/>Web特定组件：HTML元素：// 在Web上使用HTML元素import { View, Text } from 'react-native';// 在Web上渲染为div和span<View style={{ padding: 16 }}> <Text>Hello Web</Text></View>Web特定库：// 使用react-web-specific库import { useMediaQuery } from 'react-responsive';const isDesktop = useMediaQuery({ minWidth: 992 });性能优化：代码分割：// 使用React.lazy进行代码分割const LazyComponent = React.lazy(() => import('./LazyComponent'));懒加载：// 懒加载图片import { Image } from 'react-native';<Image source={{ uri: 'https://example.com/image.jpg' }} loading="lazy"/>缓存策略：// 配置Service Worker进行缓存// 在public/sw.js中配置PWA配置：创建manifest.json：{ "name": "My Expo App", "short_name": "MyApp", "start_url": "/", "display": "standalone", "background_color": "#ffffff", "theme_color": "#000000", "icons": [ { "src": "/assets/icon-192.png", "sizes": "192x192", "type": "image/png" } ]}配置Service Worker：// public/sw.jsself.addEventListener('install', event => { event.waitUntil( caches.open('v1').then(cache => { return cache.addAll([ '/', '/index.html', '/static/js/main.js' ]); }) );});部署Web应用：构建生产版本：npx expo export:web部署到Vercel：# 安装Vercel CLInpm i -g vercel# 部署vercel部署到Netlify：# 安装Netlify CLInpm i -g netlify-cli# 部署netlify deploy --prod常见问题：样式差异：Web和移动端样式可能有所不同，需要测试和调整API兼容性：某些移动端API在Web上不可用，需要提供替代方案性能问题：Web版本可能比移动端慢，需要优化加载和渲染触摸事件：Web需要同时支持鼠标和触摸事件键盘导航：Web需要支持键盘导航和无障碍访问最佳实践：渐进增强：先实现核心功能，然后为Web添加特定优化响应式设计：确保应用在不同屏幕尺寸上都能良好显示性能监控：使用Web性能工具监控和优化加载速度SEO优化：添加meta标签和结构化数据测试覆盖：在多个浏览器和设备上测试Web版本Expo for Web使开发者能够用一套代码构建真正的跨平台应用，大大提高了开发效率和代码复用率。

Expo提供了丰富的开发工具和调试功能，帮助开发者提高开发效率和代码质量。掌握这些工具对于Expo开发至关重要。核心开发工具：Expo CLIExpo CLI是主要的命令行工具，提供项目创建、开发服务器启动、构建等功能。常用命令：# 创建新项目npx create-expo-app my-app# 启动开发服务器npx expo start# 清除缓存npx expo start -c# 查看设备信息npx expo start --tunnel# 生成应用图标npx expo install expo-app-iconExpo Dev ToolsExpo Dev Tools是基于Web的开发工具界面，提供可视化的项目管理功能。功能：设备连接管理日志查看性能监控快速刷新控制网络请求监控React Native DebuggerReact Native Debugger是一个独立的调试工具，集成了React DevTools和Redux DevTools。使用方法：# 安装npm install -g react-native-debugger# 启动react-native-debugger调试技巧：Console调试使用console.log输出调试信息：console.log('Debug info');console.warn('Warning message');console.error('Error message');// 使用console.group组织日志console.group('User Data');console.log('Name:', user.name);console.log('Age:', user.age);console.groupEnd();React DevToolsReact DevTools提供组件树查看、props检查、状态监控等功能。使用方法：// 在开发环境中启用if (__DEV__) { const DevTools = require('react-devtools'); DevTools.connectToDevTools({ host: 'localhost', port: 8097, });}FlipperFlipper是Facebook开发的移动应用调试工具，支持网络请求、数据库、布局检查等。配置Flipper：// 在metro.config.js中const { getDefaultConfig } = require('expo/metro-config');const config = getDefaultConfig(__dirname);module.exports = config;ReactotronReactotron是一个强大的调试工具，支持Redux、API调用、日志等功能。配置Reactotron：import Reactotron from 'reactotron-react-native';if (__DEV__) { const tron = Reactotron .configure() .useReactNative() .connect(); console.tron = tron;}性能优化工具：性能监控使用React Native Performance API：import { Performance } from 'react-native';// 记录性能标记Performance.mark('component-start');// 组件渲染完成后Performance.mark('component-end');// 测量性能Performance.measure('component-render', 'component-start', 'component-end');内存分析使用Flipper或React Native Debugger查看内存使用情况：监控内存泄漏分析组件渲染性能优化图片和资源加载Bundle分析使用webpack-bundle-analyzer分析bundle大小：npm install --save-dev @expo/webpack-config webpack-bundle-analyzer错误处理：错误边界使用React错误边界捕获组件错误：class ErrorBoundary extends React.Component { state = { hasError: false }; static getDerivedStateFromError(error) { return { hasError: true }; } componentDidCatch(error, errorInfo) { console.error('Error caught by boundary:', error, errorInfo); } render() { if (this.state.hasError) { return <Text>Something went wrong.</Text>; } return this.props.children; }}全局错误处理监听全局错误事件：// JavaScript错误const defaultErrorHandler = ErrorUtils.getGlobalHandler();ErrorUtils.setGlobalHandler((error, isFatal) => { console.error('Global error:', error); defaultErrorHandler(error, isFatal);});// Promise错误process.on('unhandledRejection', (error) => { console.error('Unhandled promise rejection:', error);});测试工具：JestJest是Expo默认的测试框架：// 示例测试import { render } from '@testing-library/react-native';import MyComponent from './MyComponent';test('renders correctly', () => { const { getByText } = render(<MyComponent />); expect(getByText('Hello')).toBeTruthy();});DetoxDetox是端到端测试框架：describe('Login Flow', () => { it('should login successfully', async () => { await element(by.id('username')).typeText('user@example.com'); await element(by.id('password')).typeText('password'); await element(by.id('login-button')).tap(); await expect(element(by.id('welcome'))).toBeVisible(); });});最佳实践：开发环境配置：使用不同的环境变量配置开发、测试和生产环境日志管理：在生产环境中禁用详细的日志输出错误追踪：集成Sentry或Bugsnag等错误追踪服务性能监控：定期监控应用性能指标自动化测试：建立完善的测试体系掌握这些调试工具和技巧，可以大大提高Expo开发的效率和质量。