一、文件操作基础

# 读取整个文件
with open("test.txt", "r", encoding="utf-8") as f:
    content = f.read()
    print(content)
逐行读取
with open("test.txt", "r", encoding="utf-8") as f:
    for line in f:
        print(line.strip())

二、文件写入

# 写入（覆盖模式）
with open("output.txt", "w", encoding="utf-8") as f:
    f.write("第一行
")
追加模式
with open("output.txt", "a", encoding="utf-8") as f:
    f.write("追加的内容
")

三、JSON 数据处理

import json
data = {"name": "小明", "age": 25}
json_str = json.dumps(data, ensure_ascii=False, indent=2)
parsed = json.loads(json_str)
print(parsed["name"])
with open("config.json", "r", encoding="utf-8") as f:
    config = json.load(f)

四、异常处理：try-except

try:
    result = 10 / 0
except ZeroDivisionError:
    print("除数不能为零！")

try:
    num = int(input("输入数字："))
except ValueError:
    print("请输入有效数字！")

五、实战：自动化备份文件夹

import os, shutil, json
from datetime import datetime

def backup_folder(src, dest):
    os.makedirs(dest, exist_ok=True)
    backup_name = f"backup_{datetime.now().strftime("%Y%m%d_%H%M%S")}"
    shutil.copytree(src, os.path.join(dest, backup_name))
    print(f"备份完成：{backup_name}")
backup_folder("/home/ubuntu/documents", "/home/ubuntu/backups")

六、常见错误

FileNotFoundError：文件路径写错了，或文件不在当前工作目录。

UnicodeEncodeError：中文编码不对。所有 open() 加 encoding="utf-8"。