Node.js基础与常用模块

若梦plus2025-12-25 16:36

Node.js基础与常用模块

目录

  1. Node.js介绍与安装
  2. Node.js核心模块详解
  3. 文件系统操作
  4. 进程管理模块
  5. 网络通信模块
  6. 数据处理模块
  7. 最佳实践与常见问题

相关资料

Node.js介绍与安装

什么是Node.js？

Node.js是一个基于Chrome V8引擎的JavaScript运行时环境，使JavaScript能够在服务器端运行。它采用事件驱动、非阻塞I/O模型，使其轻量且高效。

Node.js的特点
graph TD A[Node.js特点] --> B[事件驱动架构] A --> C[非阻塞I/O] A --> D[单线程模型] A --> E[跨平台支持] A --> F[丰富的包生态] B --> B1[基于事件循环] B --> B2[高并发处理] C --> C1[异步操作] C --> C2[高效资源利用] D --> D1[避免线程切换开销] D --> D2[简化并发编程] E --> E1[Windows/macOS/Linux] E --> E2[容器化支持] F --> F1[npm生态系统] F --> F2[模块化开发]

核心优势：

  • 高性能：基于V8引擎的快速执行
  • 高并发：事件循环机制处理大量并发连接
  • 统一语言栈：前后端使用同一种语言
  • 实时应用：非常适合构建实时应用（如聊天室、游戏服务器）

安装Node.js

为什么选择Volta？

Volta是一个快速、可靠的JavaScript工具链管理器，具有以下优势：

  • 跨平台兼容：Windows、macOS、Linux全平台支持
  • 项目级版本管理：每个项目可以使用不同的Node.js版本
  • 无缝切换：自动检测并切换到项目所需的版本
  • 速度快：用Rust编写，启动速度极快
  • 团队协作：确保团队使用统一的工具版本
还有其他选择
工具 优点 缺点 推荐场景
Volta 快速、自动切换、团队友好 相对较新 现代开发团队
nvm 成熟稳定、功能丰富 Windows支持不佳 Unix系统
fnm 速度快、跨平台 功能相对简单 个人开发
n 简单易用 仅支持Unix 简单场景

使用Volta安装Node.js

在Windows上安装Volta
javascript 复制代码 
// 使用PowerShell安装
// 下载并运行安装脚本
curl https://get.volta.sh | bash

// 或者从官网下载安装包
// https://github.com/volta-cli/volta/releases
在macOS/Linux上安装Volta
bash 复制代码 
# 使用curl安装
curl https://get.volta.sh | bash

# 重新加载shell配置
source ~/.bashrc
# 或者
source ~/.zshrc

# 验证安装
volta --version
安装Node.js和npm
bash 复制代码 
# 安装最新LTS版本的Node.js
volta install node

# 安装特定版本
volta install node@18.17.0

# 安装npm特定版本
volta install npm@9.8.0

# 查看已安装的工具
volta list

创建并管理项目

使用npm初始化项目
bash 复制代码 
# 创建项目目录
mkdir my-node-app
cd my-node-app

# 初始化package.json
npm init -y

# 或者交互式初始化
npm init

package.json示例：

javascript 复制代码 
{
  "name": "my-node-app",
  "version": "1.0.0",
  "description": "Node.js应用示例",
  "main": "index.js",
  "scripts": {
    "start": "node index.js",
    "dev": "nodemon index.js",
    "test": "jest",
    "lint": "eslint .",
    "build": "webpack --mode production"
  },
  "keywords": ["node", "javascript", "api"],
  "author": "Your Name",
  "license": "MIT",
  "volta": {
    "node": "18.17.0",
    "npm": "9.8.0"
  },
  "dependencies": {
    "express": "^4.18.2",
    "dotenv": "^16.3.1"
  },
  "devDependencies": {
    "nodemon": "^3.0.1",
    "eslint": "^8.47.0",
    "jest": "^29.6.2"
  }
}
安装依赖
bash 复制代码 
# 安装生产依赖
npm install express
npm install --save express  # 等价写法

# 安装开发依赖
npm install --save-dev nodemon
npm install -D eslint  # 简写形式

# 安装全局依赖
npm install -g pm2

# 安装所有依赖
npm install

# 安装指定版本
npm install express@4.18.2

编写与调试Node.js程序

创建一个简单的服务器
javascript 复制代码 
// index.js - 基础HTTP服务器
const http = require('node:http');
const url = require('node:url');

// 创建服务器
const server = http.createServer((req, res) => {
    const parsedUrl = url.parse(req.url, true);
    const path = parsedUrl.pathname;
    const method = req.method;
    
    // 设置响应头
    res.setHeader('Content-Type', 'application/json');
    res.setHeader('Access-Control-Allow-Origin', '*');
    
    // 路由处理
    if (path === '/' && method === 'GET') {
        res.statusCode = 200;
        res.end(JSON.stringify({
            message: '欢迎使用Node.js服务器',
            timestamp: new Date().toISOString(),
            pid: process.pid
        }));
    } else if (path === '/health' && method === 'GET') {
        res.statusCode = 200;
        res.end(JSON.stringify({
            status: 'healthy',
            uptime: process.uptime(),
            memory: process.memoryUsage()
        }));
    } else {
        res.statusCode = 404;
        res.end(JSON.stringify({
            error: '页面未找到',
            path
        }));
    }
});

// 错误处理
server.on('error', (error) => {
    console.error('服务器错误:', error);
});

// 启动服务器
const PORT = process.env.PORT || 3000;
server.listen(PORT, () => {
    console.log(`服务器运行在 http://localhost:${PORT}`);
});
javascript 复制代码 
// express-server.js - 使用Express框架
const express = require('express');
const path = require('node:path');

const app = express();

// 中间件配置
app.use(express.json());
app.use(express.urlencoded({ extended: true }));
app.use(express.static(path.join(__dirname, 'public')));

// 日志中间件
app.use((req, res, next) => {
    console.log(`${new Date().toISOString()} - ${req.method} ${req.url}`);
    next();
});

// 路由定义
app.get('/', (req, res) => {
    res.json({
        message: 'Express服务器运行中',
        version: require('./package.json').version,
        environment: process.env.NODE_ENV || 'development'
    });
});

app.get('/api/users', (req, res) => {
    // 模拟用户数据
    const users = [
        { id: 1, name: '张三', email: 'zhangsan@example.com' },
        { id: 2, name: '李四', email: 'lisi@example.com' }
    ];
    res.json(users);
});

app.post('/api/users', (req, res) => {
    const { name, email } = req.body;
    
    if (!name || !email) {
        return res.status(400).json({
            error: '姓名和邮箱不能为空'
        });
    }
    
    const newUser = {
        id: Date.now(),
        name,
        email,
        createdAt: new Date().toISOString()
    };
    
    res.status(201).json(newUser);
});

// 错误处理中间件
app.use((error, req, res, next) => {
    console.error('错误:', error);
    res.status(500).json({
        error: '服务器内部错误'
    });
});

// 404处理
app.use((req, res) => {
    res.status(404).json({
        error: '接口不存在'
    });
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
    console.log(`Express服务器运行在端口 ${PORT}`);
});
运行项目
bash 复制代码 
# 直接运行
node index.js

# 使用npm scripts
npm start
npm run dev

# 使用PM2（生产环境）
pm2 start index.js --name "my-app"
pm2 status
pm2 logs my-app
使用npm脚本调试
javascript 复制代码 
// package.json中的scripts配置
{
  "scripts": {
    "start": "node index.js",
    "dev": "nodemon --inspect index.js",
    "dev:watch": "nodemon --watch src --ext js,json index.js",
    "debug": "node --inspect-brk index.js",
    "test": "jest",
    "test:watch": "jest --watch",
    "lint": "eslint .",
    "lint:fix": "eslint . --fix",
    "build": "webpack --mode production"
  }
}

调试配置：

bash 复制代码 
# 启动调试模式
npm run debug

# 使用Chrome DevTools调试
# 打开 chrome://inspect
# 点击 "inspect" 链接

# VS Code调试配置 (.vscode/launch.json)
json 复制代码 
{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "启动程序",
      "type": "node",
      "request": "launch",
      "program": "${workspaceFolder}/index.js",
      "env": {
        "NODE_ENV": "development"
      },
      "console": "integratedTerminal"
    },
    {
      "name": "调试测试",
      "type": "node",
      "request": "launch",
      "program": "${workspaceFolder}/node_modules/.bin/jest",
      "args": ["--runInBand"],
      "console": "integratedTerminal"
    }
  ]
}

Node.js核心模块详解

模块系统概述

Node.js采用CommonJS模块系统，同时支持ES模块。以下是核心模块的分类：

graph TD A[Node.js核心模块] --> B[文件系统] A --> C[网络通信] A --> D[进程管理] A --> E[数据处理] A --> F[实用工具] B --> B1[fs - 文件系统] B --> B2[path - 路径处理] C --> C1[http/https - HTTP服务] C --> C2[net - TCP网络] C --> C3[dgram - UDP协议] D --> D1[process - 进程对象] D --> D2[child_process - 子进程] D --> D3[cluster - 集群] E --> E1[buffer - 二进制数据] E --> E2[stream - 数据流] E --> E3[crypto - 加密] F --> F1[util - 实用函数] F --> F2[os - 操作系统] F --> F3[events - 事件发射器]

常见问题解析

1. 为什么有时使用node:fs，而有时使用fs？

历史背景与最佳实践：

javascript 复制代码 
// 传统方式（向后兼容）
const fs = require('fs');
const path = require('path');
const http = require('http');

// 现代方式（Node.js 14+）
const fs = require('node:fs');
const path = require('node:path');
const http = require('node:http');

使用场景对比：

方式 优点 缺点 推荐场景
fs 向后兼容、简洁 可能的命名冲突 兼容老版本Node.js
node:fs 明确标识核心模块、避免冲突 需要Node.js 14+ 现代项目、团队开发

实际应用示例：

javascript 复制代码 
// 可能的问题：第三方模块命名冲突
// 如果安装了名为'fs'的第三方包
const fs = require('fs'); // 可能引用第三方模块

// 解决方案：使用node:前缀
const fs = require('node:fs'); // 确保使用核心模块

// ES模块中的使用
import { readFile } from 'node:fs/promises';
import { join } from 'node:path';
2. 什么是Buffer和Streams？两者有什么区别？

Buffer：二进制数据处理

javascript 复制代码 
// Buffer基础用法
const buffer1 = Buffer.alloc(10); // 创建10字节的buffer
const buffer2 = Buffer.from('Hello World', 'utf8'); // 从字符串创建
const buffer3 = Buffer.from([0x48, 0x65, 0x6c, 0x6c, 0x6f]); // 从数组创建

// Buffer操作示例
class BufferExample {
    static basicOperations() {
        const buf = Buffer.from('Node.js Buffer示例');
        
        console.log('Buffer长度:', buf.length);
        console.log('Buffer内容:', buf.toString('utf8'));
        console.log('Buffer十六进制:', buf.toString('hex'));
        console.log('Buffer Base64:', buf.toString('base64'));
        
        // 写入数据
        const writeBuf = Buffer.alloc(20);
        writeBuf.write('Hello', 0, 'utf8');
        writeBuf.write(' World', 5, 'utf8');
        console.log('写入结果:', writeBuf.toString());
        
        return buf;
    }
    
    static bufferConversion() {
        // JSON数据的Buffer处理
        const jsonData = { name: '张三', age: 25 };
        const jsonString = JSON.stringify(jsonData);
        const jsonBuffer = Buffer.from(jsonString, 'utf8');
        
        console.log('原始数据:', jsonData);
        console.log('Buffer大小:', jsonBuffer.length);
        
        // 解析回JSON
        const parsedData = JSON.parse(jsonBuffer.toString('utf8'));
        console.log('解析结果:', parsedData);
    }
}

BufferExample.basicOperations();
BufferExample.bufferConversion();

Streams：流式数据处理

javascript 复制代码 
const fs = require('node:fs');
const { Transform, pipeline } = require('node:stream');
const { promisify } = require('node:util');

// 可读流示例
class CustomReadableStream extends require('node:stream').Readable {
    constructor(options) {
        super(options);
        this.current = 0;
        this.max = 5;
    }
    
    _read() {
        if (this.current < this.max) {
            this.push(`数据块 ${this.current++}\n`);
        } else {
            this.push(null); // 结束流
        }
    }
}

// 可写流示例
class CustomWritableStream extends require('node:stream').Writable {
    constructor(options) {
        super(options);
        this.chunks = [];
    }
    
    _write(chunk, encoding, callback) {
        console.log(`接收到数据: ${chunk.toString()}`);
        this.chunks.push(chunk);
        callback();
    }
    
    _final(callback) {
        console.log('所有数据处理完成');
        console.log('总数据量:', Buffer.concat(this.chunks).length);
        callback();
    }
}

// 转换流示例
class UpperCaseTransform extends Transform {
    _transform(chunk, encoding, callback) {
        const upperChunk = chunk.toString().toUpperCase();
        callback(null, upperChunk);
    }
}

// 流的实际应用
async function streamExamples() {
    // 文件流处理
    const readStream = fs.createReadStream('input.txt');
    const writeStream = fs.createWriteStream('output.txt');
    const transform = new UpperCaseTransform();
    
    // 使用pipeline处理流（推荐方式）
    const pipelineAsync = promisify(pipeline);
    
    try {
        await pipelineAsync(readStream, transform, writeStream);
        console.log('文件处理完成');
    } catch (error) {
        console.error('流处理错误:', error);
    }
    
    // 自定义流使用
    const customRead = new CustomReadableStream();
    const customWrite = new CustomWritableStream();
    
    customRead.pipe(customWrite);
}

// 大文件处理示例
class LargeFileProcessor {
    static async processLargeFile(inputPath, outputPath) {
        const readStream = fs.createReadStream(inputPath, { 
            highWaterMark: 64 * 1024 // 64KB chunks
        });
        const writeStream = fs.createWriteStream(outputPath);
        
        let totalBytes = 0;
        let chunkCount = 0;
        
        // 监听流事件
        readStream.on('data', (chunk) => {
            totalBytes += chunk.length;
            chunkCount++;
            console.log(`处理第 ${chunkCount} 个数据块, 大小: ${chunk.length} 字节`);
        });
        
        readStream.on('end', () => {
            console.log(`文件处理完成, 总大小: ${totalBytes} 字节`);
        });
        
        readStream.on('error', (error) => {
            console.error('读取错误:', error);
        });
        
        writeStream.on('error', (error) => {
            console.error('写入错误:', error);
        });
        
        // 使用管道传输
        readStream.pipe(writeStream);
    }
}

streamExamples().catch(console.error);

Buffer vs Streams对比：

特性 Buffer Streams
内存使用 一次性加载到内存 分块处理，内存效率高
适用场景 小文件、完整数据处理 大文件、实时数据
处理方式 同步/异步操作 异步流式处理
性能 快速随机访问 高吞吐量处理
复杂度 简单直接 需要理解流概念

文件系统操作

fs模块深度应用

javascript 复制代码 
const fs = require('node:fs');
const fsPromises = require('node:fs/promises');
const path = require('node:path');

class FileSystemManager {
    constructor(basePath = './') {
        this.basePath = basePath;
    }
    
    // 文件基础操作
    async fileOperations() {
        try {
            // 读取文件（多种方式）
            const data1 = await fsPromises.readFile('config.json', 'utf8');
            console.log('异步读取:', JSON.parse(data1));
            
            // 同步读取（谨慎使用）
            const data2 = fs.readFileSync('config.json', 'utf8');
            console.log('同步读取:', JSON.parse(data2));
            
            // 写入文件
            const newData = { 
                updated: new Date().toISOString(),
                version: '1.0.1'
            };
            await fsPromises.writeFile('config.json', JSON.stringify(newData, null, 2));
            console.log('文件写入成功');
            
            // 追加内容
            await fsPromises.appendFile('log.txt', `日志时间: ${new Date()}\n`);
            
        } catch (error) {
            console.error('文件操作错误:', error);
        }
    }
    
    // 目录操作
    async directoryOperations() {
        const dirPath = path.join(this.basePath, 'testDir');
        
        try {
            // 创建目录
            await fsPromises.mkdir(dirPath, { recursive: true });
            console.log('目录创建成功');
            
            // 读取目录内容
            const files = await fsPromises.readdir(dirPath, { withFileTypes: true });
            
            for (const file of files) {
                const filePath = path.join(dirPath, file.name);
                const stats = await fsPromises.stat(filePath);
                
                console.log({
                    name: file.name,
                    isDirectory: file.isDirectory(),
                    isFile: file.isFile(),
                    size: stats.size,
                    created: stats.birthtime,
                    modified: stats.mtime
                });
            }
            
        } catch (error) {
            console.error('目录操作错误:', error);
        }
    }
    
    // 文件监听
    watchFiles(watchPath) {
        const watcher = fs.watch(watchPath, { recursive: true }, (eventType, filename) => {
            console.log(`文件变化: ${eventType} - ${filename}`);
            
            if (eventType === 'change') {
                this.handleFileChange(path.join(watchPath, filename));
            }
        });
        
        // 优雅关闭监听
        process.on('SIGINT', () => {
            watcher.close();
            console.log('文件监听已关闭');
            process.exit(0);
        });
        
        return watcher;
    }
    
    async handleFileChange(filePath) {
        try {
            const stats = await fsPromises.stat(filePath);
            console.log(`文件 ${filePath} 已修改，大小: ${stats.size} 字节`);
        } catch (error) {
            console.error('获取文件信息失败:', error);
        }
    }
    
    // 文件复制和移动
    async copyAndMove() {
        try {
            // 复制文件
            await fsPromises.copyFile('source.txt', 'backup.txt');
            console.log('文件复制成功');
            
            // 重命名/移动文件
            await fsPromises.rename('backup.txt', 'moved-backup.txt');
            console.log('文件移动成功');
            
            // 删除文件
            await fsPromises.unlink('moved-backup.txt');
            console.log('文件删除成功');
            
        } catch (error) {
            console.error('文件操作失败:', error);
        }
    }
}

// 高级文件处理类
class AdvancedFileProcessor {
    // 批量文件处理
    static async processFilesInBatch(directory, processor) {
        const files = await fsPromises.readdir(directory);
        const results = [];
        
        // 并发处理（控制并发数）
        const concurrency = 5;
        for (let i = 0; i < files.length; i += concurrency) {
            const batch = files.slice(i, i + concurrency);
            const batchPromises = batch.map(file => 
                processor(path.join(directory, file))
            );
            
            const batchResults = await Promise.allSettled(batchPromises);
            results.push(...batchResults);
        }
        
        return results;
    }
    
    // 文件压缩示例
    static async compressFile(inputPath, outputPath) {
        const zlib = require('node:zlib');
        const readStream = fs.createReadStream(inputPath);
        const writeStream = fs.createWriteStream(outputPath);
        const gzipStream = zlib.createGzip();
        
        return new Promise((resolve, reject) => {
            readStream
                .pipe(gzipStream)
                .pipe(writeStream)
                .on('finish', resolve)
                .on('error', reject);
        });
    }
    
    // 文件完整性检查
    static async calculateChecksum(filePath, algorithm = 'sha256') {
        const crypto = require('node:crypto');
        const hash = crypto.createHash(algorithm);
        const stream = fs.createReadStream(filePath);
        
        for await (const chunk of stream) {
            hash.update(chunk);
        }
        
        return hash.digest('hex');
    }
}

// 使用示例
const fileManager = new FileSystemManager();
fileManager.fileOperations();
fileManager.directoryOperations();

path模块实用工具

javascript 复制代码 
const path = require('node:path');

class PathUtils {
    static demonstratePathOperations() {
        const filePath = '/Users/username/projects/node-app/src/index.js';
        
        console.log('路径操作示例:');
        console.log('原始路径:', filePath);
        console.log('目录名:', path.dirname(filePath));
        console.log('文件名:', path.basename(filePath));
        console.log('扩展名:', path.extname(filePath));
        console.log('解析结果:', path.parse(filePath));
        
        // 路径拼接
        const newPath = path.join('/Users', 'username', 'projects', 'new-file.txt');
        console.log('拼接路径:', newPath);
        
        // 相对路径转换
        const relativePath = path.relative('/Users/username', filePath);
        console.log('相对路径:', relativePath);
        
        // 绝对路径解析
        const absolutePath = path.resolve('./src', '../config.json');
        console.log('绝对路径:', absolutePath);
    }
    
    // 跨平台路径处理
    static crossPlatformPaths() {
        // Windows: C:\Users\username\file.txt
        // Unix: /home/username/file.txt
        
        const configPath = path.join(process.cwd(), 'config', 'app.json');
        const logPath = path.join(process.cwd(), 'logs', 'app.log');
        
        console.log('配置文件路径:', configPath);
        console.log('日志文件路径:', logPath);
        console.log('平台分隔符:', path.sep);
        console.log('路径分隔符:', path.delimiter);
    }
}

PathUtils.demonstratePathOperations();
PathUtils.crossPlatformPaths();

进程管理模块

process对象详解

javascript 复制代码 
class ProcessManager {
    constructor() {
        this.setupProcessHandlers();
    }
    
    // 进程信息获取
    getProcessInfo() {
        const info = {
            // 基础信息
            pid: process.pid,
            ppid: process.ppid,
            platform: process.platform,
            arch: process.arch,
            version: process.version,
            versions: process.versions,
            
            // 运行时信息
            uptime: process.uptime(),
            cwd: process.cwd(),
            execPath: process.execPath,
            argv: process.argv,
            
            // 内存使用情况
            memoryUsage: process.memoryUsage(),
            
            // CPU使用情况
            cpuUsage: process.cpuUsage(),
            
            // 环境变量
            env: {
                NODE_ENV: process.env.NODE_ENV,
                PORT: process.env.PORT,
                // 只显示部分环境变量
                PATH: process.env.PATH ? '...(隐藏)' : undefined
            }
        };
        
        return info;
    }
    
    // 命令行参数处理
    parseCommandLineArgs() {
        const args = process.argv.slice(2); // 去掉node和脚本路径
        const parsedArgs = {};
        const flags = [];
        
        for (let i = 0; i < args.length; i++) {
            const arg = args[i];
            
            if (arg.startsWith('--')) {
                // 长选项 --key=value 或 --key value
                const [key, value] = arg.slice(2).split('=');
                if (value !== undefined) {
                    parsedArgs[key] = value;
                } else if (i + 1 < args.length && !args[i + 1].startsWith('-')) {
                    parsedArgs[key] = args[++i];
                } else {
                    parsedArgs[key] = true;
                }
            } else if (arg.startsWith('-')) {
                // 短选项 -p 3000
                const key = arg.slice(1);
                if (i + 1 < args.length && !args[i + 1].startsWith('-')) {
                    parsedArgs[key] = args[++i];
                } else {
                    flags.push(key);
                }
            } else {
                // 位置参数
                if (!parsedArgs._) parsedArgs._ = [];
                parsedArgs._.push(arg);
            }
        }
        
        return { args: parsedArgs, flags };
    }
    
    // 进程信号处理
    setupProcessHandlers() {
        // 优雅关闭
        process.on('SIGTERM', this.handleShutdown.bind(this));
        process.on('SIGINT', this.handleShutdown.bind(this));
        
        // 未捕获异常
        process.on('uncaughtException', (error) => {
            console.error('未捕获异常:', error);
            // 记录错误后退出
            this.logError(error);
            process.exit(1);
        });
        
        // 未处理的Promise拒绝
        process.on('unhandledRejection', (reason, promise) => {
            console.error('未处理的Promise拒绝:', reason);
            console.error('在Promise:', promise);
            // 可以选择退出或继续运行
            this.logError(reason);
        });
        
        // 警告事件
        process.on('warning', (warning) => {
            console.warn('Node.js警告:', warning.name);
            console.warn('消息:', warning.message);
            console.warn('堆栈:', warning.stack);
        });
    }
    
    async handleShutdown(signal) {
        console.log(`接收到${signal}信号，开始优雅关闭...`);
        
        try {
            // 清理资源
            await this.cleanup();
            
            console.log('应用已优雅关闭');
            process.exit(0);
        } catch (error) {
            console.error('关闭过程中出错:', error);
            process.exit(1);
        }
    }
    
    async cleanup() {
        // 关闭数据库连接
        // 停止定时器
        // 完成当前请求
        // 等等清理工作
        console.log('执行清理工作...');
        await new Promise(resolve => setTimeout(resolve, 1000));
    }
    
    logError(error) {
        const errorLog = {
            timestamp: new Date().toISOString(),
            error: error.message,
            stack: error.stack,
            pid: process.pid,
            memory: process.memoryUsage()
        };
        
        // 这里可以写入文件或发送到日志服务
        console.error('错误详情:', JSON.stringify(errorLog, null, 2));
    }
    
    // 进程性能监控
    startPerformanceMonitoring(interval = 10000) {
        const monitor = setInterval(() => {
            const usage = process.memoryUsage();
            const cpu = process.cpuUsage();
            
            console.log('性能指标:', {
                timestamp: new Date().toISOString(),
                memory: {
                    rss: Math.round(usage.rss / 1024 / 1024) + 'MB',
                    heapUsed: Math.round(usage.heapUsed / 1024 / 1024) + 'MB',
                    heapTotal: Math.round(usage.heapTotal / 1024 / 1024) + 'MB',
                    external: Math.round(usage.external / 1024 / 1024) + 'MB'
                },
                cpu: {
                    user: cpu.user,
                    system: cpu.system
                },
                uptime: Math.round(process.uptime()) + 's'
            });
        }, interval);
        
        return monitor;
    }
}

// 使用示例
const processManager = new ProcessManager();

console.log('进程信息:');
console.log(JSON.stringify(processManager.getProcessInfo(), null, 2));

console.log('\n命令行参数:');
console.log(processManager.parseCommandLineArgs());

// 启动性能监控
const monitor = processManager.startPerformanceMonitoring(5000);

// 5分钟后停止监控
setTimeout(() => {
    clearInterval(monitor);
    console.log('性能监控已停止');
}, 300000);

child_process和cluster区别详解

javascript 复制代码 
// child_process示例
const { spawn, exec, fork } = require('node:child_process');
const path = require('node:path');

class ChildProcessManager {
    // exec使用示例 - 执行shell命令
    static async executeCommand(command) {
        return new Promise((resolve, reject) => {
            exec(command, { timeout: 10000 }, (error, stdout, stderr) => {
                if (error) {
                    reject({ error, stderr });
                } else {
                    resolve(stdout);
                }
            });
        });
    }
    
    // spawn使用示例 - 长时间运行的进程
    static runLongProcess() {
        const child = spawn('node', ['-e', `
            setInterval(() => {
                console.log('子进程运行中...', new Date().toISOString());
            }, 2000);
        `]);
        
        child.stdout.on('data', (data) => {
            console.log(`子进程输出: ${data}`);
        });
        
        child.stderr.on('data', (data) => {
            console.error(`子进程错误: ${data}`);
        });
        
        child.on('close', (code) => {
            console.log(`子进程退出，代码: ${code}`);
        });
        
        return child;
    }
    
    // fork使用示例 - Node.js子进程通信
    static createWorker() {
        const workerScript = `
            // worker.js
            process.on('message', (msg) => {
                console.log('Worker收到消息:', msg);
                
                if (msg.type === 'compute') {
                    const result = msg.data.reduce((sum, num) => sum + num, 0);
                    process.send({
                        type: 'result',
                        data: result,
                        workerId: process.pid
                    });
                }
            });
            
            process.send({ type: 'ready', workerId: process.pid });
        `;
        
        // 创建临时worker文件
        const fs = require('node:fs');
        const workerPath = path.join(__dirname, 'temp-worker.js');
        fs.writeFileSync(workerPath, workerScript);
        
        const worker = fork(workerPath);
        
        worker.on('message', (msg) => {
            console.log('主进程收到消息:', msg);
            
            if (msg.type === 'ready') {
                // 发送计算任务
                worker.send({
                    type: 'compute',
                    data: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
                });
            } else if (msg.type === 'result') {
                console.log('计算结果:', msg.data);
                worker.kill();
                // 清理临时文件
                fs.unlinkSync(workerPath);
            }
        });
        
        return worker;
    }
}

// cluster使用示例
const cluster = require('node:cluster');
const http = require('node:http');
const numCPUs = require('node:os').cpus().length;

class ClusterManager {
    static setupCluster() {
        if (cluster.isMaster) {
            this.setupMaster();
        } else {
            this.setupWorker();
        }
    }
    
    static setupMaster() {
        console.log(`主进程 ${process.pid} 正在运行`);
        
        // 创建工作进程
        for (let i = 0; i < Math.min(4, numCPUs); i++) {
            cluster.fork();
        }
        
        // 监听工作进程事件
        cluster.on('online', (worker) => {
            console.log(`工作进程 ${worker.process.pid} 已上线`);
        });
        
        cluster.on('exit', (worker, code, signal) => {
            console.log(`工作进程 ${worker.process.pid} 已退出`);
            
            // 自动重启工作进程
            if (!worker.exitedAfterDisconnect) {
                console.log('重启工作进程...');
                cluster.fork();
            }
        });
        
        // 优雅关闭
        process.on('SIGTERM', () => {
            console.log('主进程收到SIGTERM信号');
            
            for (const id in cluster.workers) {
                cluster.workers[id].kill();
            }
        });
        
        // 工作进程负载监控
        setInterval(() => {
            const workers = Object.keys(cluster.workers).length;
            console.log(`当前活跃工作进程数: ${workers}`);
        }, 10000);
    }
    
    static setupWorker() {
        // 创建HTTP服务器
        const server = http.createServer((req, res) => {
            const startTime = Date.now();
            
            // 模拟一些处理时间
            setTimeout(() => {
                const processTime = Date.now() - startTime;
                
                res.writeHead(200, { 'Content-Type': 'application/json' });
                res.end(JSON.stringify({
                    pid: process.pid,
                    timestamp: new Date().toISOString(),
                    processTime: processTime,
                    url: req.url,
                    method: req.method
                }));
            }, Math.random() * 100); // 0-100ms的随机延迟
        });
        
        server.listen(3000, () => {
            console.log(`工作进程 ${process.pid} 监听端口 3000`);
        });
        
        // 优雅关闭处理
        process.on('SIGTERM', () => {
            console.log(`工作进程 ${process.pid} 收到SIGTERM信号`);
            
            server.close(() => {
                process.exit(0);
            });
        });
    }
}

// 使用示例
async function demonstrateChildProcess() {
    try {
        // 执行系统命令
        const result = await ChildProcessManager.executeCommand('ls -la');
        console.log('命令执行结果:', result);
        
        // 创建长时间运行的子进程
        const longProcess = ChildProcessManager.runLongProcess();
        
        // 5秒后终止
        setTimeout(() => {
            longProcess.kill();
        }, 5000);
        
        // 创建worker进程
        ChildProcessManager.createWorker();
        
    } catch (error) {
        console.error('子进程操作失败:', error);
    }
}

// 启动集群（需要在单独文件中运行）
// ClusterManager.setupCluster();

demonstrateChildProcess();

child_process vs cluster 对比总结：

特性 child_process cluster
目的 通用子进程创建和管理 专门用于HTTP服务器集群
灵活性 可执行任何程序 仅限Node.js应用
负载均衡 需要手动实现 自动负载均衡
进程通信 多种方式（IPC、流、管道） 内置IPC通信
适用场景 外部命令、CPU密集任务 Web服务器、API服务
复杂度 需要更多手动管理 更高级的抽象

网络通信模块

HTTP服务器高级应用

javascript 复制代码 
const http = require('node:http');
const https = require('node:https');
const fs = require('node:fs');
const url = require('node:url');
const querystring = require('node:querystring');

class HTTPServerManager {
    constructor() {
        this.server = null;
        this.connections = new Set();
    }
    
    // 创建基础HTTP服务器
    createBasicServer(port = 3000) {
        this.server = http.createServer((req, res) => {
            this.handleRequest(req, res);
        });
        
        // 连接管理
        this.server.on('connection', (socket) => {
            this.connections.add(socket);
            socket.on('close', () => {
                this.connections.delete(socket);
            });
        });
        
        this.server.listen(port, () => {
            console.log(`HTTP服务器运行在端口 ${port}`);
        });
        
        return this.server;
    }
    
    async handleRequest(req, res) {
        const startTime = Date.now();
        const parsedUrl = url.parse(req.url, true);
        const pathname = parsedUrl.pathname;
        const method = req.method;
        
        // 设置通用响应头
        res.setHeader('Content-Type', 'application/json; charset=utf-8');
        res.setHeader('X-Powered-By', 'Node.js');
        res.setHeader('Access-Control-Allow-Origin', '*');
        
        try {
            // 路由处理
            if (pathname === '/' && method === 'GET') {
                this.handleHome(req, res);
            } else if (pathname === '/api/users' && method === 'GET') {
                await this.handleGetUsers(req, res);
            } else if (pathname === '/api/users' && method === 'POST') {
                await this.handleCreateUser(req, res);
            } else if (pathname.startsWith('/api/users/') && method === 'GET') {
                const userId = pathname.split('/')[3];
                await this.handleGetUser(req, res, userId);
            } else if (pathname === '/upload' && method === 'POST') {
                await this.handleFileUpload(req, res);
            } else {
                this.handleNotFound(req, res);
            }
            
        } catch (error) {
            this.handleError(req, res, error);
        }
        
        // 记录请求日志
        const duration = Date.now() - startTime;
        console.log(`${method} ${pathname} - ${res.statusCode} - ${duration}ms`);
    }
    
    handleHome(req, res) {
        const serverInfo = {
            message: '欢迎使用Node.js HTTP服务器',
            timestamp: new Date().toISOString(),
            server: {
                platform: process.platform,
                nodeVersion: process.version,
                pid: process.pid,
                uptime: process.uptime()
            },
            memory: process.memoryUsage(),
            endpoints: [
                'GET /',
                'GET /api/users',
                'POST /api/users',
                'GET /api/users/:id',
                'POST /upload'
            ]
        };
        
        res.statusCode = 200;
        res.end(JSON.stringify(serverInfo, null, 2));
    }
    
    async handleGetUsers(req, res) {
        // 模拟从数据库获取用户
        const users = [
            { id: 1, name: '张三', email: 'zhangsan@example.com', createdAt: new Date().toISOString() },
            { id: 2, name: '李四', email: 'lisi@example.com', createdAt: new Date().toISOString() }
        ];
        
        // 模拟异步操作
        await new Promise(resolve => setTimeout(resolve, 100));
        
        res.statusCode = 200;
        res.end(JSON.stringify({
            data: users,
            total: users.length,
            timestamp: new Date().toISOString()
        }));
    }
    
    async handleCreateUser(req, res) {
        const body = await this.parseRequestBody(req);
        
        try {
            const userData = JSON.parse(body);
            
            // 验证数据
            if (!userData.name || !userData.email) {
                res.statusCode = 400;
                res.end(JSON.stringify({
                    error: '姓名和邮箱不能为空',
                    code: 'VALIDATION_ERROR'
                }));
                return;
            }
            
            // 创建新用户（模拟）
            const newUser = {
                id: Date.now(),
                name: userData.name,
                email: userData.email,
                createdAt: new Date().toISOString()
            };
            
            res.statusCode = 201;
            res.end(JSON.stringify({
                message: '用户创建成功',
                data: newUser
            }));
            
        } catch (error) {
            res.statusCode = 400;
            res.end(JSON.stringify({
                error: '无效的JSON格式',
                code: 'INVALID_JSON'
            }));
        }
    }
    
    async handleGetUser(req, res, userId) {
        // 模拟数据库查询
        await new Promise(resolve => setTimeout(resolve, 50));
        
        if (!userId || isNaN(userId)) {
            res.statusCode = 400;
            res.end(JSON.stringify({
                error: '无效的用户ID',
                code: 'INVALID_USER_ID'
            }));
            return;
        }
        
        // 模拟用户数据
        const user = {
            id: parseInt(userId),
            name: `用户${userId}`,
            email: `user${userId}@example.com`,
            profile: {
                age: 25 + parseInt(userId),
                city: '北京',
                hobbies: ['阅读', '编程', '旅游']
            },
            createdAt: new Date().toISOString()
        };
        
        res.statusCode = 200;
        res.end(JSON.stringify({
            data: user,
            timestamp: new Date().toISOString()
        }));
    }
    
    async handleFileUpload(req, res) {
        try {
            const contentType = req.headers['content-type'];
            
            if (!contentType || !contentType.includes('multipart/form-data')) {
                res.statusCode = 400;
                res.end(JSON.stringify({
                    error: '请使用multipart/form-data格式上传文件',
                    code: 'INVALID_CONTENT_TYPE'
                }));
                return;
            }
            
            const body = await this.parseRequestBody(req);
            const uploadInfo = {
                size: body.length,
                timestamp: new Date().toISOString(),
                contentType: contentType
            };
            
            // 这里应该处理实际的文件上传逻辑
            // 保存文件、生成文件名等
            
            res.statusCode = 200;
            res.end(JSON.stringify({
                message: '文件上传成功',
                uploadInfo
            }));
            
        } catch (error) {
            res.statusCode = 500;
            res.end(JSON.stringify({
                error: '文件上传失败',
                code: 'UPLOAD_ERROR'
            }));
        }
    }
    
    handleNotFound(req, res) {
        res.statusCode = 404;
        res.end(JSON.stringify({
            error: '页面未找到',
            code: 'NOT_FOUND',
            path: req.url,
            method: req.method,
            timestamp: new Date().toISOString()
        }));
    }
    
    handleError(req, res, error) {
        console.error('服务器错误:', error);
        
        res.statusCode = 500;
        res.end(JSON.stringify({
            error: '服务器内部错误',
            code: 'INTERNAL_ERROR',
            timestamp: new Date().toISOString(),
            // 开发环境下可以返回错误详情
            ...(process.env.NODE_ENV === 'development' && {
                details: error.message,
                stack: error.stack
            })
        }));
    }
    
    // 解析请求体
    parseRequestBody(req) {
        return new Promise((resolve, reject) => {
            let body = '';
            req.on('data', chunk => {
                body += chunk.toString();
            });
            req.on('end', () => {
                resolve(body);
            });
            req.on('error', reject);
        });
    }
    
    // 优雅关闭服务器
    async gracefulShutdown() {
        return new Promise((resolve) => {
            console.log('开始关闭HTTP服务器...');
            
            // 停止接受新连接
            this.server.close(() => {
                console.log('HTTP服务器已关闭');
                resolve();
            });
            
            // 关闭现有连接
            for (const connection of this.connections) {
                connection.end();
            }
            
            // 5秒后强制关闭
            setTimeout(() => {
                for (const connection of this.connections) {
                    connection.destroy();
                }
                resolve();
            }, 5000);
        });
    }
}

// HTTPS服务器
class HTTPSServerManager extends HTTPServerManager {
    createHTTPSServer(port = 443, certOptions) {
        const options = certOptions || {
            key: fs.readFileSync('path/to/private-key.pem'),
            cert: fs.readFileSync('path/to/certificate.pem')
        };
        
        this.server = https.createServer(options, (req, res) => {
            this.handleRequest(req, res);
        });
        
        this.server.listen(port, () => {
            console.log(`HTTPS服务器运行在端口 ${port}`);
        });
        
        return this.server;
    }
}

// 使用示例
const httpManager = new HTTPServerManager();
httpManager.createBasicServer(3000);

// 优雅关闭处理
process.on('SIGTERM', async () => {
    await httpManager.gracefulShutdown();
    process.exit(0);
});

process.on('SIGINT', async () => {
    await httpManager.gracefulShutdown();
    process.exit(0);
});

WebSocket通信示例

javascript 复制代码 
// 注意：这是一个WebSocket的简化实现示例
const http = require('node:http');
const crypto = require('node:crypto');

class SimpleWebSocketServer {
    constructor(port = 8080) {
        this.port = port;
        this.clients = new Set();
        this.server = this.createServer();
    }
    
    createServer() {
        const server = http.createServer();
        
        server.on('upgrade', (request, socket, head) => {
            this.handleUpgrade(request, socket, head);
        });
        
        return server;
    }
    
    handleUpgrade(request, socket, head) {
        const key = request.headers['sec-websocket-key'];
        const acceptKey = this.generateAcceptKey(key);
        
        const responseHeaders = [
            'HTTP/1.1 101 Switching Protocols',
            'Upgrade: websocket',
            'Connection: Upgrade',
            `Sec-WebSocket-Accept: ${acceptKey}`,
            '',
            ''
        ].join('\r\n');
        
        socket.write(responseHeaders);
        
        // 创建WebSocket连接
        const client = {
            socket,
            id: crypto.randomUUID(),
            connected: true
        };
        
        this.clients.add(client);
        console.log(`客户端连接: ${client.id}`);
        
        socket.on('data', (data) => {
            this.handleMessage(client, data);
        });
        
        socket.on('close', () => {
            this.clients.delete(client);
            console.log(`客户端断开: ${client.id}`);
        });
        
        // 发送欢迎消息
        this.sendMessage(client, {
            type: 'welcome',
            message: '欢迎连接WebSocket服务器',
            clientId: client.id
        });
    }
    
    generateAcceptKey(key) {
        const magicString = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11';
        const hash = crypto.createHash('sha1');
        hash.update(key + magicString);
        return hash.digest('base64');
    }
    
    handleMessage(client, data) {
        try {
            // 简化的消息解析（实际WebSocket协议更复杂）
            const message = JSON.parse(data.toString());
            console.log(`收到消息 from ${client.id}:`, message);
            
            // 广播消息给所有客户端
            this.broadcast({
                type: 'message',
                from: client.id,
                data: message,
                timestamp: new Date().toISOString()
            }, client);
            
        } catch (error) {
            console.error('消息解析错误:', error);
        }
    }
    
    sendMessage(client, message) {
        if (client.connected && !client.socket.destroyed) {
            const data = JSON.stringify(message);
            client.socket.write(data);
        }
    }
    
    broadcast(message, excludeClient = null) {
        for (const client of this.clients) {
            if (client !== excludeClient) {
                this.sendMessage(client, message);
            }
        }
    }
    
    start() {
        this.server.listen(this.port, () => {
            console.log(`WebSocket服务器运行在端口 ${this.port}`);
        });
    }
}

// 使用第三方WebSocket库的示例（推荐）
// npm install ws
/*
const WebSocket = require('ws');

class WebSocketServerManager {
    constructor(port = 8080) {
        this.port = port;
        this.wss = new WebSocket.Server({ port });
        this.clients = new Map();
        this.setupServer();
    }
    
    setupServer() {
        this.wss.on('connection', (ws, req) => {
            const clientId = crypto.randomUUID();
            this.clients.set(clientId, { ws, id: clientId, ip: req.socket.remoteAddress });
            
            console.log(`客户端连接: ${clientId} from ${req.socket.remoteAddress}`);
            
            // 发送欢迎消息
            ws.send(JSON.stringify({
                type: 'welcome',
                clientId,
                message: '连接成功'
            }));
            
            // 处理消息
            ws.on('message', (data) => {
                this.handleMessage(clientId, data);
            });
            
            // 处理断开
            ws.on('close', () => {
                this.clients.delete(clientId);
                console.log(`客户端断开: ${clientId}`);
            });
            
            // 心跳检测
            const heartbeat = setInterval(() => {
                if (ws.readyState === WebSocket.OPEN) {
                    ws.ping();
                } else {
                    clearInterval(heartbeat);
                }
            }, 30000);
            
            ws.on('pong', () => {
                console.log(`收到心跳响应: ${clientId}`);
            });
        });
    }
    
    handleMessage(clientId, data) {
        try {
            const message = JSON.parse(data.toString());
            console.log(`消息来自 ${clientId}:`, message);
            
            // 根据消息类型处理
            switch (message.type) {
                case 'chat':
                    this.handleChatMessage(clientId, message);
                    break;
                case 'broadcast':
                    this.handleBroadcastMessage(clientId, message);
                    break;
                default:
                    console.log('未知消息类型:', message.type);
            }
            
        } catch (error) {
            console.error('消息处理错误:', error);
        }
    }
    
    handleChatMessage(senderId, message) {
        const response = {
            type: 'chat',
            from: senderId,
            message: message.content,
            timestamp: new Date().toISOString()
        };
        
        // 发送给所有客户端
        this.broadcast(response);
    }
    
    handleBroadcastMessage(senderId, message) {
        const response = {
            type: 'broadcast',
            from: senderId,
            message: message.content,
            timestamp: new Date().toISOString()
        };
        
        // 发送给除发送者外的所有客户端
        this.broadcast(response, senderId);
    }
    
    broadcast(message, excludeClientId = null) {
        const data = JSON.stringify(message);
        
        this.clients.forEach((client, clientId) => {
            if (clientId !== excludeClientId && client.ws.readyState === WebSocket.OPEN) {
                client.ws.send(data);
            }
        });
    }
    
    sendToClient(clientId, message) {
        const client = this.clients.get(clientId);
        if (client && client.ws.readyState === WebSocket.OPEN) {
            client.ws.send(JSON.stringify(message));
        }
    }
    
    getClientCount() {
        return this.clients.size;
    }
}

// 使用示例
const wsManager = new WebSocketServerManager(8080);
console.log('WebSocket服务器已启动');

// 定期广播服务器状态
setInterval(() => {
    wsManager.broadcast({
        type: 'server-status',
        clientCount: wsManager.getClientCount(),
        timestamp: new Date().toISOString(),
        uptime: process.uptime()
    });
}, 60000);
*/

// 启动简化版WebSocket服务器
const wsServer = new SimpleWebSocketServer(8080);
wsServer.start();

数据处理模块

加密解密与安全

javascript 复制代码 
const crypto = require('node:crypto');

class CryptoUtils {
    // 哈希函数
    static createHash(data, algorithm = 'sha256') {
        return crypto.createHash(algorithm).update(data).digest('hex');
    }
    
    // 密码哈希（带盐值）
    static hashPassword(password, salt = null) {
        if (!salt) {
            salt = crypto.randomBytes(16).toString('hex');
        }
        
        const hash = crypto.pbkdf2Sync(password, salt, 100000, 64, 'sha512');
        return {
            salt,
            hash: hash.toString('hex'),
            combined: salt + ':' + hash.toString('hex')
        };
    }
    
    // 验证密码
    static verifyPassword(password, storedHash) {
        const [salt, originalHash] = storedHash.split(':');
        const { hash } = this.hashPassword(password, salt);
        return hash === originalHash;
    }
    
    // 对称加密
    static encrypt(text, key = null) {
        if (!key) {
            key = crypto.randomBytes(32); // 256位密钥
        }
        
        const iv = crypto.randomBytes(16); // 初始化向量
        const cipher = crypto.createCipher('aes-256-cbc', key);
        
        let encrypted = cipher.update(text, 'utf8', 'hex');
        encrypted += cipher.final('hex');
        
        return {
            encrypted,
            key: key.toString('hex'),
            iv: iv.toString('hex')
        };
    }
    
    // 对称解密
    static decrypt(encryptedData, key) {
        const decipher = crypto.createDecipher('aes-256-cbc', Buffer.from(key, 'hex'));
        
        let decrypted = decipher.update(encryptedData, 'hex', 'utf8');
        decrypted += decipher.final('utf8');
        
        return decrypted;
    }
    
    // RSA密钥对生成
    static generateRSAKeyPair() {
        return crypto.generateKeyPairSync('rsa', {
            modulusLength: 2048,
            publicKeyEncoding: {
                type: 'spki',
                format: 'pem'
            },
            privateKeyEncoding: {
                type: 'pkcs8',
                format: 'pem'
            }
        });
    }
    
    // RSA加密
    static rsaEncrypt(text, publicKey) {
        return crypto.publicEncrypt(publicKey, Buffer.from(text, 'utf8')).toString('base64');
    }
    
    // RSA解密
    static rsaDecrypt(encryptedText, privateKey) {
        return crypto.privateDecrypt(privateKey, Buffer.from(encryptedText, 'base64')).toString('utf8');
    }
    
    // 数字签名
    static sign(data, privateKey) {
        const sign = crypto.createSign('RSA-SHA256');
        sign.update(data);
        return sign.sign(privateKey, 'base64');
    }
    
    // 验证签名
    static verify(data, signature, publicKey) {
        const verify = crypto.createVerify('RSA-SHA256');
        verify.update(data);
        return verify.verify(publicKey, signature, 'base64');
    }
}

// JWT令牌处理（简化版）
class JWTHelper {
    static base64URLEncode(str) {
        return Buffer.from(str)
            .toString('base64')
            .replace(/\+/g, '-')
            .replace(/\//g, '_')
            .replace(/=/g, '');
    }
    
    static base64URLDecode(str) {
        str += new Array(5 - str.length % 4).join('=');
        return Buffer.from(str.replace(/\-/g, '+').replace(/_/g, '/'), 'base64').toString();
    }
    
    static createToken(payload, secret, expiresIn = '1h') {
        const header = {
            alg: 'HS256',
            typ: 'JWT'
        };
        
        const now = Math.floor(Date.now() / 1000);
        const exp = now + (parseInt(expiresIn) * 3600); // 简化处理，假设都是小时
        
        const tokenPayload = {
            ...payload,
            iat: now,
            exp: exp
        };
        
        const encodedHeader = this.base64URLEncode(JSON.stringify(header));
        const encodedPayload = this.base64URLEncode(JSON.stringify(tokenPayload));
        
        const signature = crypto
            .createHmac('sha256', secret)
            .update(encodedHeader + '.' + encodedPayload)
            .digest('base64')
            .replace(/\+/g, '-')
            .replace(/\//g, '_')
            .replace(/=/g, '');
        
        return `${encodedHeader}.${encodedPayload}.${signature}`;
    }
    
    static verifyToken(token, secret) {
        try {
            const [encodedHeader, encodedPayload, signature] = token.split('.');
            
            // 验证签名
            const expectedSignature = crypto
                .createHmac('sha256', secret)
                .update(encodedHeader + '.' + encodedPayload)
                .digest('base64')
                .replace(/\+/g, '-')
                .replace(/\//g, '_')
                .replace(/=/g, '');
            
            if (signature !== expectedSignature) {
                throw new Error('Invalid signature');
            }
            
            // 解析payload
            const payload = JSON.parse(this.base64URLDecode(encodedPayload));
            
            // 检查过期时间
            const now = Math.floor(Date.now() / 1000);
            if (payload.exp && payload.exp < now) {
                throw new Error('Token expired');
            }
            
            return { valid: true, payload };
            
        } catch (error) {
            return { valid: false, error: error.message };
        }
    }
}

// 使用示例
console.log('=== 加密解密示例 ===');

// 哈希函数
const text = 'Hello Node.js Crypto';
const hash = CryptoUtils.createHash(text);
console.log('文本:', text);
console.log('SHA256哈希:', hash);

// 密码哈希
const password = 'mySecurePassword123';
const hashedPassword = CryptoUtils.hashPassword(password);
console.log('密码哈希:', hashedPassword.combined);

const isValid = CryptoUtils.verifyPassword(password, hashedPassword.combined);
console.log('密码验证:', isValid);

// 对称加密
const { encrypted, key } = CryptoUtils.encrypt('敏感数据需要加密');
console.log('加密后:', encrypted);

const decrypted = CryptoUtils.decrypt(encrypted, key);
console.log('解密后:', decrypted);

// RSA非对称加密
const { publicKey, privateKey } = CryptoUtils.generateRSAKeyPair();
const rsaEncrypted = CryptoUtils.rsaEncrypt('RSA加密测试', publicKey);
console.log('RSA加密后:', rsaEncrypted);

const rsaDecrypted = CryptoUtils.rsaDecrypt(rsaEncrypted, privateKey);
console.log('RSA解密后:', rsaDecrypted);

// 数字签名
const dataToSign = '重要文档内容';
const signature = CryptoUtils.sign(dataToSign, privateKey);
console.log('数字签名:', signature);

const signatureValid = CryptoUtils.verify(dataToSign, signature, publicKey);
console.log('签名验证:', signatureValid);

// JWT令牌
const jwtSecret = 'myJWTSecret';
const token = JWTHelper.createToken({ userId: 123, role: 'admin' }, jwtSecret, '2');
console.log('JWT令牌:', token);

const tokenVerification = JWTHelper.verifyToken(token, jwtSecret);
console.log('JWT验证:', tokenVerification);

最佳实践与常见问题

性能优化建议

javascript 复制代码 
class PerformanceOptimizer {
    // 内存使用监控
    static monitorMemoryUsage() {
        const usage = process.memoryUsage();
        
        return {
            rss: Math.round(usage.rss / 1024 / 1024), // 常驻内存
            heapUsed: Math.round(usage.heapUsed / 1024 / 1024), // 已用堆内存
            heapTotal: Math.round(usage.heapTotal / 1024 / 1024), // 堆内存总量
            external: Math.round(usage.external / 1024 / 1024), // 外部内存
            arrayBuffers: Math.round(usage.arrayBuffers / 1024 / 1024) // ArrayBuffer内存
        };
    }
    
    // 事件循环延迟监控
    static measureEventLoopDelay() {
        const { performance, PerformanceObserver } = require('perf_hooks');
        
        return new Promise((resolve) => {
            const start = performance.now();
            setImmediate(() => {
                const delay = performance.now() - start;
                resolve(delay);
            });
        });
    }
    
    // 流式处理大文件
    static async processLargeFileStream(inputPath, processor) {
        const fs = require('node:fs');
        const readline = require('node:readline');
        
        const fileStream = fs.createReadStream(inputPath);
        const rl = readline.createInterface({
            input: fileStream,
            crlfDelay: Infinity
        });
        
        let lineCount = 0;
        for await (const line of rl) {
            await processor(line, lineCount++);
            
            // 定期让出控制权给事件循环
            if (lineCount % 1000 === 0) {
                await new Promise(resolve => setImmediate(resolve));
            }
        }
        
        return lineCount;
    }
    
    // 对象池模式（减少GC压力）
    static createObjectPool(factory, resetFn, initialSize = 10) {
        const pool = [];
        
        // 初始化对象池
        for (let i = 0; i < initialSize; i++) {
            pool.push(factory());
        }
        
        return {
            acquire() {
                return pool.length > 0 ? pool.pop() : factory();
            },
            
            release(obj) {
                resetFn(obj);
                pool.push(obj);
            },
            
            size() {
                return pool.length;
            }
        };
    }
}

// 错误处理最佳实践
class ErrorHandler {
    constructor() {
        this.setupGlobalHandlers();
    }
    
    setupGlobalHandlers() {
        process.on('uncaughtException', (error) => {
            console.error('未捕获异常:', error);
            this.logError(error, 'UNCAUGHT_EXCEPTION');
            
            // 优雅关闭
            this.gracefulShutdown(1);
        });
        
        process.on('unhandledRejection', (reason, promise) => {
            console.error('未处理的Promise拒绝:', reason);
            this.logError(reason, 'UNHANDLED_REJECTION', { promise });
        });
        
        process.on('warning', (warning) => {
            console.warn('Node.js警告:', warning);
            this.logError(warning, 'NODE_WARNING');
        });
    }
    
    logError(error, type, context = {}) {
        const errorInfo = {
            timestamp: new Date().toISOString(),
            type,
            message: error.message,
            stack: error.stack,
            context,
            process: {
                pid: process.pid,
                memory: process.memoryUsage(),
                uptime: process.uptime()
            }
        };
        
        // 写入错误日志文件
        const fs = require('node:fs');
        const logFile = `error-${new Date().toISOString().split('T')[0]}.log`;
        fs.appendFileSync(logFile, JSON.stringify(errorInfo) + '\n');
        
        // 发送到监控系统
        this.sendToMonitoring(errorInfo);
    }
    
    sendToMonitoring(errorInfo) {
        // 这里可以集成监控系统，如Sentry、DataDog等
        console.log('错误已记录到监控系统:', errorInfo.type);
    }
    
    async gracefulShutdown(code = 0) {
        console.log('开始优雅关闭...');
        
        try {
            // 关闭服务器
            // 关闭数据库连接
            // 清理资源
            
            setTimeout(() => {
                console.log('强制退出');
                process.exit(1);
            }, 10000);
            
            process.exit(code);
        } catch (error) {
            console.error('关闭过程出错:', error);
            process.exit(1);
        }
    }
}

// 配置管理最佳实践
class ConfigManager {
    constructor() {
        this.config = this.loadConfig();
        this.validateConfig();
    }
    
    loadConfig() {
        const env = process.env.NODE_ENV || 'development';
        
        const defaultConfig = {
            port: 3000,
            database: {
                host: 'localhost',
                port: 5432,
                name: 'myapp'
            },
            redis: {
                host: 'localhost',
                port: 6379
            },
            jwt: {
                expiresIn: '24h'
            },
            logging: {
                level: 'info'
            }
        };
        
        const envConfig = {
            development: {
                logging: { level: 'debug' }
            },
            production: {
                port: process.env.PORT || 8080,
                database: {
                    host: process.env.DB_HOST,
                    port: process.env.DB_PORT,
                    name: process.env.DB_NAME,
                    user: process.env.DB_USER,
                    password: process.env.DB_PASSWORD
                },
                redis: {
                    host: process.env.REDIS_HOST,
                    port: process.env.REDIS_PORT,
                    password: process.env.REDIS_PASSWORD
                },
                jwt: {
                    secret: process.env.JWT_SECRET,
                    expiresIn: process.env.JWT_EXPIRES_IN || '24h'
                }
            }
        };
        
        return this.mergeConfig(defaultConfig, envConfig[env] || {});
    }
    
    mergeConfig(defaultConfig, envConfig) {
        const merged = { ...defaultConfig };
        
        for (const [key, value] of Object.entries(envConfig)) {
            if (typeof value === 'object' && !Array.isArray(value)) {
                merged[key] = { ...merged[key], ...value };
            } else {
                merged[key] = value;
            }
        }
        
        return merged;
    }
    
    validateConfig() {
        const required = [
            'port',
            'database.host',
            'database.port',
            'database.name'
        ];
        
        if (process.env.NODE_ENV === 'production') {
            required.push(
                'database.user',
                'database.password',
                'jwt.secret'
            );
        }
        
        const missing = required.filter(path => {
            const keys = path.split('.');
            let current = this.config;
            
            for (const key of keys) {
                if (!current[key]) return true;
                current = current[key];
            }
            
            return false;
        });
        
        if (missing.length > 0) {
            throw new Error(`缺少必需配置: ${missing.join(', ')}`);
        }
    }
    
    get(path, defaultValue = undefined) {
        const keys = path.split('.');
        let current = this.config;
        
        for (const key of keys) {
            if (!current[key]) return defaultValue;
            current = current[key];
        }
        
        return current;
    }
}

// 使用示例
console.log('=== 性能监控示例 ===');
console.log('内存使用:', PerformanceOptimizer.monitorMemoryUsage());

PerformanceOptimizer.measureEventLoopDelay().then(delay => {
    console.log('事件循环延迟:', delay + 'ms');
});

// 对象池使用示例
const bufferPool = PerformanceOptimizer.createObjectPool(
    () => Buffer.alloc(1024),
    (buffer) => buffer.fill(0),
    5
);

const buffer = bufferPool.acquire();
console.log('从对象池获取buffer，池大小:', bufferPool.size());
bufferPool.release(buffer);
console.log('返回buffer到对象池，池大小:', bufferPool.size());

// 初始化错误处理和配置管理
const errorHandler = new ErrorHandler();
const configManager = new ConfigManager();

console.log('应用配置:', {
    port: configManager.get('port'),
    dbHost: configManager.get('database.host'),
    logLevel: configManager.get('logging.level')
});
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