Python进阶指南之os.path模块拼接文件路径的使用技巧

# ❌ 危险写法（不推荐）
path = "C:" + "Users" + "John" + "file.txt"
print(path)  # 输出：C:UsersJohnfile.txt （缺少分隔符！）

import os

# 安全拼接路径
base_dir = "C:\\Users\\John"
sub_dir = "Projects"
filename = "main.py"

full_path = os.path.join(base_dir, sub_dir, filename)
print(full_path)
# Windows 输出：C:\Users\John\Projects\main.py
# Linux/macOS 输出：C:/Users/John/Projects/main.py

# 多余的斜杠不会出错
path = os.path.join("folder", "//subfolder//", "file.txt")
print(path)  # folder/subfolder/file.txt (自动标准化)

relative_path = "data/input.csv"
absolute_path = os.path.abspath(relative_path)
print(absolute_path)
# 假设当前工作目录是 /home/user/project
# 输出：/home/user/project/data/input.csv

path = "/home/user/documents/report.pdf"

dir_name = os.path.dirname(path)
file_name = os.path.basename(path)

print(f"目录: {dir_name}")     # 目录: /home/user/documents
print(f"文件: {file_name}")    # 文件: report.pdf

# 批量移动文件
files = ["a.txt", "b.py", "c.md"]
for f in files:
    src = os.path.join("temp", f)
    dst = os.path.join("backup", os.path.basename(src))
    print(f"移动 {src} → {dst}")

import os

path = "config/settings.json"

if os.path.exists(path):
    if os.path.isfile(path):
        print("这是一个文件，可以读取。")
    elif os.path.isdir(path):
        print("这是一个目录。")
else:
    print("路径不存在！请检查路径是否正确。")

path = "/var/log/app.log"

directory, filename = os.path.split(path)
print(directory)    # /var/log
print(filename)     # app.log

filename = "script.py"

name, ext = os.path.splitext(filename)
print(name)   # script
print(ext)    # .py

def is_json_file(filepath):
    _, ext = os.path.splitext(filepath)
    return ext.lower() == '.json'

print(is_json_file("data/config.json"))  # True
print(is_json_file("data/script.py"))    # False

path = "C:\\Users\\..\\Documents\\./file.txt"

normalized = os.path.normpath(path)
print(normalized)  # C:\Documents\file.txt

# normcase 对大小写敏感的操作系统（如 Windows）有特殊处理
case_normalized = os.path.normcase(path)
print(case_normalized)  # c:\documents\file.txt (全部小写)

import os
import datetime

def archive_old_logs(log_dir="logs", days=7):
    # 1. 确保归档目录存在
    archive_dir = os.path.join(log_dir, "archive")
    os.makedirs(archive_dir, exist_ok=True)

    # 2. 获取当前时间
    cutoff_date = datetime.datetime.now() - datetime.timedelta(days=days)

    # 3. 遍历所有日志文件
    for filename in os.listdir(log_dir):
        file_path = os.path.join(log_dir, filename)

        # 跳过非文件（如子目录）
        if not os.path.isfile(file_path):
            continue

        # 4. 获取文件创建时间（注意：不是修改时间）
        try:
            file_time = datetime.datetime.fromtimestamp(os.path.getctime(file_path))
        except OSError:
            continue  # 无法访问时间信息则跳过

        # 5. 判断是否超过期限
        if file_time < cutoff_date:
            # 6. 移动文件到归档目录
            dest_path = os.path.join(archive_dir, filename)
            os.rename(file_path, dest_path)
            print(f"已归档: {filename}")

# 调用函数
archive_old_logs()

# ❌ 错误示范
path = "data/" + "user.json"

# ✅ 正确做法
path = os.path.join("data", "user.json")

from pathlib import Path

# 等价于 os.path.join("data", "config.json")
p = Path("data") / "config.json"
print(p)  # data/config.json

# 检查是否存在
if p.exists():
    print("配置文件存在！")

import os
from pathlib import Path

class PathManager:
    def __init__(self, base_dir):
        self.base = Path(base_dir)

    def get(self, *parts):
        """安全生成路径"""
        return self.base.joinpath(*parts).resolve()

    def ensure_dir(self, *parts):
        """确保目录存在"""
        path = self.get(*parts)
        path.mkdir(parents=True, exist_ok=True)
        return path

    def is_valid_file(self, *parts):
        """检查文件是否存在且为文件"""
        path = self.get(*parts)
        return path.is_file()

# 使用示例
pm = PathManager("/project")

# 生成数据目录
data_dir = pm.ensure_dir("data", "raw")

# 读取配置
config_path = pm.get("config", "app.json")
if pm.is_valid_file("config", "app.json"):
    print(f"加载配置: {config_path}")

# 错误：硬编码斜杠
path = "folder\\file.txt"  # Windows 特定

# 可能抛出 OSError
os.path.getsize("nonexistent.txt")

if os.path.exists("file.txt") and os.path.isfile("file.txt"):
    size = os.path.getsize("file.txt")
    print(f"文件大小: {size} bytes")

import os

# 获取当前脚本所在目录
script_dir = os.path.dirname(os.path.abspath(__file__))
config_path = os.path.join(script_dir, "config.json")