Python yaml格式配置文件操作实战教程

# 字符串 (通常不需要引号，除非有特殊字符)
name: John Doe
company: "CSDN & Co." # 包含特殊字符&，建议加引号
title: This is a title

# 数字
age: 29
score: 89.5

# 布尔值
is_active: true  # 或 True, TRUE
is_admin: false  # 或 False, FALSE

# 空值
salary: null     # 或 Null, NULL, ~

# 日期和时间
date: 2023-10-27
datetime: 2023-10-27T15:30:00+08:00

fruits:
  - Apple
  - Banana
  - Orange

# 行内写法 (类似JSON数组)
colors: [red, blue, green]

person:
  name: Alice
  age: 25
  address: Beijing

# 行内写法 (类似JSON对象)
coordinates: { x: 12.5, y: -7.2 }

# 一个列表中包含多个字典
users:
  - name: John
    id: 1
    hobbies:
      - reading
      - hiking
  - name: Jane
    id: 2
    hobbies:
      - gaming
      - cooking

# 一个字典中某个值是列表
server:
  ip: 192.168.1.1
  ports:
    - 80
    - 443
    - 8080

# 锚点(&)和别名(*) - 避免重复
defaults: &defaults
  adapter: postgres
  host: localhost

development:
  <<: *defaults  # 合并defaults的内容
  database: dev_db

test:
  <<: *defaults
  database: test_db

# 多行字符串
description: |
  This is a long text
  that spans multiple
  lines.           # 保留换行符

signature: >
  This will fold
  into a single
  line.            # 将换行折叠为空格

pip install pyyaml

# config.yml
database:
  host: localhost
  port: 3306
  username: admin
  password: secret123
  db_name: my_app

logging:
  level: INFO
  file: /var/log/my_app.log
  rotation: 5

features:
  enable_upload: true
  allowed_file_types:
    - .jpg
    - .png
    - .pdf

import yaml
import pathlib

# 推荐使用 pathlib 处理路径
config_path = pathlib.Path('config.yml')

# 使用 safe_load() 而不是 load() 以避免安全风险！
with config_path.open('r', encoding='utf-8') as f:
    config_data = yaml.safe_load(f)

# 现在可以像操作普通字典一样访问配置
print(config_data['database']['host'])  # 输出: localhost
print(config_data['features']['enable_upload'])  # 输出: True

# 获取日志配置
log_level = config_data['logging']['level']
print(f"日志级别是: {log_level}")

import yaml

# 要写入的 Python 数据
data_to_write = {
    'project': 'Awesome Project',
    'author': 'CSDN Blogger',
    'tags': ['python', 'tutorial', 'yaml'],
    'config': {
        'timeout': 30,
        'retries': 3
    }
}

# 写入文件
with open('output.yml', 'w', encoding='utf-8') as f:
    # safe_dump() 同样比 dump() 更安全
    # allow_unicode: 确保中文等字符正确显示
    # indent: 指定缩进空格数，让文件更美观
    yaml.safe_dump(
        data_to_write,
        f,
        allow_unicode=True,
        indent=2 # 可选，使用2空格缩进，更美观
    )

# 也可以直接生成一个YAML字符串
yaml_string = yaml.safe_dump(data_to_write, allow_unicode=True)
print(yaml_string)

author: CSDN Blogger
config:
  retries: 3
  timeout: 30
project: Awesome Project
tags:
- python
- tutorial
- yaml

my_app/
├── config.yml
└── app.py

# config.yml
app:
  name: My Python Application
  version: 1.0.0
  environment: development # production / staging

database:
  url: mysql+pymysql://user:pass@localhost:3306/dev_db
  pool_size: 5
  echo_sql: false

api:
  endpoint: https://api.example.com/v1
  timeout_seconds: 10
  retries: 2
  api_key: YOUR_API_KEY_HERE # 切记不要在代码中提交真实密钥！

logging:
  level: DEBUG
  format: "%(asctime)s - %(name)s - %(levelname)s - %(message)s"

# app.py
import yaml
import pathlib
import logging
from typing import Dict, Any

def load_config(config_file: pathlib.Path) -> Dict[str, Any]:
    """加载YAML配置文件"""
    if not config_file.exists():
        raise FileNotFoundError(f"配置文件 {config_file} 未找到！")
    
    with config_file.open('r', encoding='utf-8') as f:
        config = yaml.safe_load(f)
    return config

def setup_logging(logging_config: Dict[str, Any]):
    """根据配置设置日志"""
    logging.basicConfig(
        level=getattr(logging, logging_config['level']),
        format=logging_config['format']
    )
    logging.info("日志系统初始化成功！")

def main():
    # 1. 加载配置
    try:
        config = load_config(pathlib.Path('config.yml'))
    except Exception as e:
        print(f"加载配置失败: {e}")
        return

    # 2. 读取应用配置
    app_config = config['app']
    print(f"启动应用: {app_config['name']} (版本: {app_config['version']})")

    # 3. 设置日志
    setup_logging(config['logging'])

    # 4. 模拟使用其他配置
    db_url = config['database']['url']
    api_endpoint = config['api']['endpoint']
    # ... 这里可以继续初始化数据库连接、API客户端等 ...

    logging.debug(f"数据库URL: {db_url}")
    logging.info(f"API端点: {api_endpoint}")
    logging.warning("这是一个警告信息！")
    print("应用初始化完成，开始运行...")

if __name__ == "__main__":
    main()

启动应用: My Python Application (版本: 1.0.0)
应用初始化完成，开始运行...