Python文件操作示例

基本操作

文件打开与关闭


# 使用with语句（推荐）
with open('example.txt', 'r', encoding='utf-8') as f:
    content = f.read()
    print(content)
# 文件会自动关闭

# 传统方式
f = open('example.txt', 'r', encoding='utf-8')
try:
    content = f.read()
    print(content)
finally:
    f.close()

文件模式


# 读取模式 'r'
with open('file.txt', 'r') as f:
    content = f.read()

# 写入模式 'w'（会覆盖原文件）
with open('file.txt', 'w') as f:
    f.write('Hello, World!')

# 追加模式 'a'
with open('file.txt', 'a') as f:
    f.write('\nNew line')

# 读写模式 'r+'
with open('file.txt', 'r+') as f:
    content = f.read()
    f.write('Additional content')

文本文件操作

读取文本文件


# 读取整个文件
with open('text.txt', 'r', encoding='utf-8') as f:
    content = f.read()
    print(content)

# 逐行读取
with open('text.txt', 'r', encoding='utf-8') as f:
    for line in f:
        print(line.strip())

# 读取所有行到列表
with open('text.txt', 'r', encoding='utf-8') as f:
    lines = f.readlines()
    print(lines)

# 读取指定字节数
with open('text.txt', 'r', encoding='utf-8') as f:
    chunk = f.read(100)  # 读取前100个字符
    print(chunk)

写入文本文件


# 写入字符串
with open('output.txt', 'w', encoding='utf-8') as f:
    f.write('Hello, World!\n')
    f.write('Another line\n')

# 写入多行
lines = ['Line 1\n', 'Line 2\n', 'Line 3\n']
with open('output.txt', 'w', encoding='utf-8') as f:
    f.writelines(lines)

# CSV文件操作
import csv

# 写入CSV
data = [
    ['Name', 'Age', 'City'],
    ['Alice', '25', 'Beijing'],
    ['Bob', '30', 'Shanghai']
]
with open('data.csv', 'w', newline='', encoding='utf-8') as f:
    writer = csv.writer(f)
    writer.writerows(data)

# 读取CSV
with open('data.csv', 'r', encoding='utf-8') as f:
    reader = csv.reader(f)
    for row in reader:
        print(row)

二进制文件操作

读写二进制文件


# 写入二进制数据
data = bytes([0x48, 0x65, 0x6C, 0x6C, 0x6F])
with open('binary.bin', 'wb') as f:
    f.write(data)

# 读取二进制数据
with open('binary.bin', 'rb') as f:
    content = f.read()
    print(content)  # b'Hello'

# 图片文件复制
def copy_image(src, dst):
    with open(src, 'rb') as source:
        with open(dst, 'wb') as dest:
            dest.write(source.read())

# 分块读取大文件
def read_in_chunks(file_path, chunk_size=8192):
    with open(file_path, 'rb') as f:
        while True:
            chunk = f.read(chunk_size)
            if not chunk:
                break
            yield chunk

目录操作

目录和文件管理


import os
import shutil

# 创建目录
os.mkdir('new_directory')
os.makedirs('path/to/nested/directory')  # 创建多级目录

# 删除文件和目录
os.remove('file.txt')  # 删除文件
os.rmdir('empty_directory')  # 删除空目录
shutil.rmtree('directory')  # 删除目录及其内容

# 复制文件和目录
shutil.copy('source.txt', 'dest.txt')  # 复制文件
shutil.copytree('src_dir', 'dst_dir')  # 复制目录

# 移动文件和目录
shutil.move('source.txt', 'dest/source.txt')

# 列出目录内容
print(os.listdir('.'))  # 列出当前目录内容
for entry in os.scandir('.'):  # 更详细的信息
    print(entry.name, entry.is_file())

文件查找和过滤


import glob
import fnmatch

# 使用glob模块
python_files = glob.glob('*.py')  # 查找所有Python文件
txt_files = glob.glob('**/*.txt', recursive=True)  # 递归查找

# 使用fnmatch模块
def find_files(directory, pattern):
    for root, dirs, files in os.walk(directory):
        for basename in files:
            if fnmatch.fnmatch(basename, pattern):
                filename = os.path.join(root, basename)
                yield filename

# 使用示例
for file in find_files('.', '*.py'):
    print(file)

路径处理

路径操作


from pathlib import Path
import os.path

# 使用pathlib（推荐）
path = Path('folder/subfolder/file.txt')
print(path.parent)  # 父目录
print(path.name)    # 文件名
print(path.suffix)  # 扩展名
print(path.stem)    # 不带扩展名的文件名

# 路径拼接
new_path = path.parent / 'another_file.txt'
print(new_path)

# 使用os.path
file_path = 'folder/subfolder/file.txt'
print(os.path.dirname(file_path))   # 目录名
print(os.path.basename(file_path))  # 文件名
print(os.path.splitext(file_path))  # 分离扩展名

# 路径判断
print(os.path.exists(file_path))    # 是否存在
print(os.path.isfile(file_path))    # 是否是文件
print(os.path.isdir(file_path))     # 是否是目录

高级应用

文件监控


import time
from watchdog.observers import Observer
from watchdog.events import FileSystemEventHandler

class MyHandler(FileSystemEventHandler):
    def on_modified(self, event):
        if not event.is_directory:
            print(f"文件被修改: {event.src_path}")

    def on_created(self, event):
        if not event.is_directory:
            print(f"新文件创建: {event.src_path}")

# 监控目录
path = "."
event_handler = MyHandler()
observer = Observer()
observer.schedule(event_handler, path, recursive=False)
observer.start()

try:
    while True:
        time.sleep(1)
except KeyboardInterrupt:
    observer.stop()
observer.join()

临时文件操作


import tempfile
import os

# 创建临时文件
with tempfile.NamedTemporaryFile(delete=False) as tmp:
    tmp.write(b'Hello World!')
    temp_path = tmp.name

# 使用临时文件
with open(temp_path, 'rb') as f:
    content = f.read()
    print(content)

# 删除临时文件
os.unlink(temp_path)

# 临时目录
with tempfile.TemporaryDirectory() as tmpdirname:
    print('创建临时目录:', tmpdirname)
    # 目录会在退出with语句后自动删除