代码示例指南

本文档展示了各种编程语言的代码示例，用于测试代码块的复制功能和翻译保护。

JavaScript 示例

以下是一个简单的 API 调用示例：

// 获取用户列表
async function fetchUsers() {
  const response = await fetch('/api/users', {
    method: 'GET',
    headers: {
      'Content-Type': 'application/json',
      'Authorization': `Bearer ${token}`
    }
  });
  
  if (!response.ok) {
    throw new Error('获取用户失败');
  }
  
  return response.json();
}

// 使用示例
const users = await fetchUsers();
console.log('用户数量:', users.length);

Python 示例

使用 Python 连接数据库：

import pymysql
from contextlib import contextmanager

@contextmanager
def get_connection():
    """获取数据库连接"""
    conn = pymysql.connect(
        host='localhost',
        user='admin',
        password='your_password',
        database='enterprise_db',
        charset='utf8mb4'
    )
    try:
        yield conn
    finally:
        conn.close()

# 查询示例
with get_connection() as conn:
    cursor = conn.cursor()
    cursor.execute("SELECT * FROM users WHERE status = %s", ('active',))
    results = cursor.fetchall()
    print(f"找到 {len(results)} 个活跃用户")

YAML 配置示例

Kubernetes 部署配置：

apiVersion: apps/v1
kind: Deployment
metadata:
  name: enterprise-api
  namespace: production
  labels:
    app: enterprise-api
    version: v1.0.0
spec:
  replicas: 3
  selector:
    matchLabels:
      app: enterprise-api
  template:
    metadata:
      labels:
        app: enterprise-api
    spec:
      containers:
        - name: api
          image: registry.example.com/enterprise-api:1.0.0
          ports:
            - containerPort: 8080
          env:
            - name: DATABASE_URL
              valueFrom:
                secretKeyRef:
                  name: db-secrets
                  key: url
          resources:
            limits:
              cpu: "500m"
              memory: "512Mi"
            requests:
              cpu: "200m"
              memory: "256Mi"

Shell 脚本示例

自动化部署脚本：

#!/bin/bash

# 部署脚本
set -e

echo "开始部署..."

# 拉取最新代码
git pull origin main

# 安装依赖
npm install

# 构建项目
npm run build

# 重启服务
pm2 restart enterprise-api

echo "部署完成！"

SQL 示例

创建用户表：

-- 创建用户表
CREATE TABLE users (
    id BIGINT PRIMARY KEY AUTO_INCREMENT,
    username VARCHAR(50) NOT NULL UNIQUE,
    email VARCHAR(100) NOT NULL UNIQUE,
    password_hash VARCHAR(255) NOT NULL,
    status ENUM('active', 'inactive', 'suspended') DEFAULT 'active',
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    INDEX idx_status (status),
    INDEX idx_email (email)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='用户表';

-- 插入测试数据
INSERT INTO users (username, email, password_hash) VALUES
    ('admin', 'admin@example.com', 'hashed_password_here'),
    ('user1', 'user1@example.com', 'hashed_password_here');

JSON 配置示例

API 响应格式：

{
  "code": 200,
  "message": "success",
  "data": {
    "users": [
      {
        "id": 1,
        "name": "张三",
        "email": "zhangsan@example.com",
        "role": "admin"
      },
      {
        "id": 2,
        "name": "李四",
        "email": "lisi@example.com",
        "role": "user"
      }
    ],
    "pagination": {
      "page": 1,
      "pageSize": 10,
      "total": 100
    }
  }
}

TypeScript 示例

类型定义和接口：

// 用户接口定义
interface User {
  id: number;
  username: string;
  email: string;
  role: 'admin' | 'user' | 'guest';
  createdAt: Date;
}

// API 响应类型
interface ApiResponse<T> {
  code: number;
  message: string;
  data: T;
}

// 用户服务类
class UserService {
  private baseUrl: string;

  constructor(baseUrl: string) {
    this.baseUrl = baseUrl;
  }

  async getUser(id: number): Promise<ApiResponse<User>> {
    const response = await fetch(`${this.baseUrl}/users/${id}`);
    return response.json();
  }

  async createUser(user: Omit<User, 'id' | 'createdAt'>): Promise<ApiResponse<User>> {
    const response = await fetch(`${this.baseUrl}/users`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify(user)
    });
    return response.json();
  }
}

总结

以上示例展示了常见编程语言的代码片段。在翻译过程中，这些代码块应该保持原样不被翻译，只有注释和字符串中的中文内容可能需要翻译。