Python文件操作入门:新手如何快速掌握文件读写技巧

file = open('example.txt', 'r')  # 以只读模式打开文件
content = file.read()  # 读取文件内容
file.close()  # 关闭文件

with open('example.txt', 'r') as file:
    content = file.read()
    # 文件会在代码块结束后自动关闭

# 读取整个文件
with open('example.txt', 'r') as file:
    content = file.read()

# 逐行读取
with open('example.txt', 'r') as file:
    for line in file:
        print(line.strip())  # strip()去除行尾换行符

# 读取所有行到列表
with open('example.txt', 'r') as file:
    lines = file.readlines()

# 写入新文件（会覆盖已有内容）
with open('output.txt', 'w') as file:
    file.write("Hello, World!\n")
    file.write("This is a new line.")

# 追加内容到已有文件
with open('output.txt', 'a') as file:
    file.write("\nAppended content.")

import os

# 获取当前工作目录
current_dir = os.getcwd()

# 组合路径（跨平台安全）
file_path = os.path.join('data', 'example.txt')

# 检查路径是否存在
if os.path.exists(file_path):
    print("文件存在")

from pathlib import Path

# 创建Path对象
file_path = Path('data') / 'example.txt'

# 检查文件
if file_path.exists():
    content = file_path.read_text()
    file_path.write_text("New content")

import json

# 写入JSON文件
config = {'name': 'Alice', 'age': 25, 'active': True}
with open('config.json', 'w') as file:
    json.dump(config, file, indent=4)

# 读取JSON文件
with open('config.json', 'r') as file:
    loaded_config = json.load(file)

import csv

# 写入CSV文件
with open('data.csv', 'w', newline='') as file:
    writer = csv.writer(file)
    writer.writerow(['Name', 'Age', 'City'])
    writer.writerow(['Alice', 25, 'New York'])
    writer.writerow(['Bob', 30, 'London'])

# 读取CSV文件
with open('data.csv', 'r') as file:
    reader = csv.reader(file)
    for row in reader:
        print(row)

import logging

logging.basicConfig(
    filename='app.log',
    level=logging.INFO,
    format='%(asctime)s - %(levelname)s - %(message)s'
)

logging.info('程序启动')
try:
    result = 10 / 0
except ZeroDivisionError:
    logging.error('除零错误', exc_info=True)

class DatabaseConnection:
    def __enter__(self):
        print("连接数据库")
        return self
    
    def __exit__(self, exc_type, exc_val, exc_tb):
        print("关闭数据库连接")
        if exc_type:
            print(f"发生错误: {exc_val}")

with DatabaseConnection() as db:
    print("执行数据库操作")
    # raise Exception("模拟错误")

import io

# 内存中的文本文件
text_buffer = io.StringIO()
text_buffer.write("Hello, ")
text_buffer.write("World!")
content = text_buffer.getvalue()
print(content)
text_buffer.close()

# 内存中的二进制文件
binary_buffer = io.BytesIO()
binary_buffer.write(b'\x01\x02\x03')
binary_content = binary_buffer.getvalue()
print(binary_content)
binary_buffer.close()

import gzip
import zipfile

# 读写gzip文件
with gzip.open('example.gz', 'wt') as f:
    f.write("压缩的文本内容")

# 创建ZIP文件
with zipfile.ZipFile('archive.zip', 'w') as zipf:
    zipf.write('example.txt')
    
# 读取ZIP文件
with zipfile.ZipFile('archive.zip', 'r') as zipf:
    zipf.extractall('extracted')

# 设置缓冲区大小（字节）
with open('large_file.txt', 'r', buffering=8192) as f:
    while True:
        chunk = f.read(4096)  # 每次读取4KB
        if not chunk:
            break
        process(chunk)

try:
    with open('missing_file.txt', 'r') as f:
        content = f.read()
except FileNotFoundError:
    print("文件不存在")
except PermissionError:
    print("没有访问权限")
except IOError as e:
    print(f"IO错误: {e}")
except Exception as e:
    print(f"未知错误: {e}")
else:
    print("文件读取成功")
finally:
    print("操作完成")

import fcntl

with open('shared_file.txt', 'a') as f:
    try:
        fcntl.flock(f, fcntl.LOCK_EX)  # 获取排他锁
        f.write("独占写入的内容\n")
    finally:
        fcntl.flock(f, fcntl.LOCK_UN)  # 释放锁

import json
from pathlib import Path
from datetime import datetime

DIARY_FILE = 'my_diary.json'

def load_diary():
    try:
        with open(DIARY_FILE, 'r') as f:
            return json.load(f)
    except (FileNotFoundError, json.JSONDecodeError):
        return []

def save_diary(entries):
    with open(DIARY_FILE, 'w') as f:
        json.dump(entries, f, indent=2)

def add_entry():
    entries = load_diary()
    timestamp = datetime.now().strftime('%Y-%m-%d %H:%M:%S')
    content = input("写下今天的日记: ")
    entries.append({'time': timestamp, 'content': content})
    save_diary(entries)
    print("日记已保存!")

def list_entries():
    entries = load_diary()
    for idx, entry in enumerate(entries, 1):
        print(f"{idx}. [{entry['time']}] {entry['content']}")

def main():
    while True:
        print("\n简易日记本")
        print("1. 写日记")
        print("2. 看日记")
        print("3. 退出")
        choice = input("请选择: ")
        
        if choice == '1':
            add_entry()
        elif choice == '2':
            list_entries()
        elif choice == '3':
            break
        else:
            print("无效选择")

if __name__ == '__main__':
    main()