1.利用内置函数获取文件对象
- 功能:
- 生成文件对象，进行创建，读写操作
- 用法:
open(path,mode)
- 参数说明∶
- path:文件路径
- mode :操作模式
- 返回值:
- 文件对象
- 举例:
f = open('d://a.txt' , ‘w')
2. 文件操作的模式之写入：
- 写入模式（“w”）：打开文件进行写入操作。如果文件已存在，则会覆盖原有内容；如果文件不存在，则会创建新文件。
- 注意：在写入模式下，如果文件已存在，原有内容将被清空。
3. 文件对象的操作方法之写入保存：
-
write(str)：将字符串str写入文件。它返回写入的字符数。file.write("Hello, world!\n") -
writelines(lines)：将字符串列表lines中的每个字符串写入文件。它不会在字符串之间添加换行符。可以通过在每个字符串末尾添加换行符来实现换行。lines = ["This is line 1\n", "This is line 2\n", "This is line 3\n"] file.writelines(lines) -
close()：关闭文件，释放文件资源。在写入完成后，应该调用该方法关闭文件。file.close()
以下是一个示例代码，演示如何使用open函数获取文件对象并进行写入保存操作：
# 打开文件并获取文件对象
file = open("example.txt", "w")
# 写入单行文本
file.write("Hello, world!\n")
# 写入多行文本
lines = ["This is line 1\n", "This is line 2\n", "This is line 3\n"]
file.writelines(lines)
# 关闭文件
file.close()
在上述示例中，我们首先使用open函数以写入模式打开名为”example.txt”的文件，获取了文件对象file。然后，我们使用文件对象的write方法写入了单行文本和writelines方法写入了多行文本。最后，我们调用了close方法关闭文件。
请确保在写入完成后调用close方法来关闭文件，以释放文件资源和确保写入的数据被保存。
操作完成后，必须使用close方法！
避坑指南：
#当打开的文件中有中文的时候，需要设置打开的编码格式为utf-8或gbk，视打开的原文件编码格式而定
实战
在这里插入代码片# coding:utf-8
# @Author: DX
# @Time: 2023/5/29
# @File: package_open.py
import os
def create_package(path):
if os.path.exists(path):
raise Exception('%s已经存在,不可创建' % path)
os.makedirs(path)
init_path = os.path.join(path, '__init__.py')
f = open(init_path, 'w', encoding='utf-8')
f.write('# coding: utf-8\n')
f.close()
class Open(object):
def __init__(self, path, mode='w', is_return=True):
self.path = path
self.mode = mode
self.is_return = is_return
def write(self, message):
f = open(self.path, mode=self.mode, encoding='utf-8')
try:
if self.is_return and message.endswith('\n'):
message = '%s\n' % message
f.write(message)
except Exception as e:
print(e)
finally:
f.close()
def read(self, is_strip=True):
result = []
with open(self.path, mode=self.mode, encoding='utf-8') as f:
data = f.readlines()
for line in data:
if is_strip:
temp = line.strip()
if temp != '':
result.append(temp)
else:
if line != '':
result.append(line)
return result
if __name__ == '__main__':
current_path = os.getcwd()
# path = os.path.join(current_path, 'test2')
# create_package(path)
open_path = os.path.join(current_path, 'b.txt')
o = open('package_datetime.py', mode='r', encoding='utf-8')
# o = os.write('你好~')
data1 = o.read()
print(data1)
输出结果（遍历了package_datetime.py中的内容）：
# coding:utf-8
# Time: 2023/5/28
# @Author: Dx
# @File:package_datetime.py
from datetime import datetime
from datetime import timedelta
now = datetime.now()
print(now, type(now))
now_str = now.strftime('%Y-%m-%d %H:%M:%S')
print(now_str, type(now_str))
now_obj = datetime.strptime(now_str, '%Y-%m-%d %H:%M:%S')
print(now_obj, type(now_obj))
print('===========================================')
three_days = timedelta(days=3) # 这个时间间隔是三天，可以代表三天前或三天后的范围
after_three_days = three_days + now
print(after_three_days)
after_three_days_str = after_three_days.strftime('%Y/%m/%d %H:%M:%S:%f')
print(after_three_days_str, type(after_three_days_str))
after_three_days_obj = datetime.strptime(after_three_days_str, '%Y/%m/%d %H:%M:%S:%f')
print(after_three_days_obj, type(after_three_days_obj))
print('===========================================')
before_three_days = now - three_days
print(before_three_days)
before_three_days_str = before_three_days.strftime('%Y/%m/%d %H:%M:%S:%f')
print(before_three_days_str, type(before_three_days_str), '=================')
before_three_days_obj = datetime.strptime(before_three_days_str, '%Y/%m/%d %H:%M:%S:%f')
print(before_three_days_obj, type(before_three_days_obj))
print('===========================================')
one_hour = timedelta(hours=1)
after_one_hour = now + one_hour
after_one_hour_str = after_one_hour.strftime('%H:%M:%S')
print(after_one_hour_str)
after_one_hour_obj = datetime.strptime(after_one_hour_str, '%H:%M:%S')
print(after_one_hour_obj, type(after_one_hour_obj))
# default_str = '2023 5 28 abc'
# default_obj = datetime.strptime(default_str, '%Y %m %d')
进程已结束,退出代码0
package_datetime.py
# coding:utf-8
# Time: 2023/5/28
# @Author: Dx
# @File:package_datetime.py
from datetime import datetime
from datetime import timedelta
now = datetime.now()
print(now, type(now))
now_str = now.strftime('%Y-%m-%d %H:%M:%S')
print(now_str, type(now_str))
now_obj = datetime.strptime(now_str, '%Y-%m-%d %H:%M:%S')
print(now_obj, type(now_obj))
print('===========================================')
three_days = timedelta(days=3) # 这个时间间隔是三天，可以代表三天前或三天后的范围
after_three_days = three_days + now
print(after_three_days)
after_three_days_str = after_three_days.strftime('%Y/%m/%d %H:%M:%S:%f')
print(after_three_days_str, type(after_three_days_str))
after_three_days_obj = datetime.strptime(after_three_days_str, '%Y/%m/%d %H:%M:%S:%f')
print(after_three_days_obj, type(after_three_days_obj))
print('===========================================')
before_three_days = now - three_days
print(before_three_days)
before_three_days_str = before_three_days.strftime('%Y/%m/%d %H:%M:%S:%f')
print(before_three_days_str, type(before_three_days_str), '=================')
before_three_days_obj = datetime.strptime(before_three_days_str, '%Y/%m/%d %H:%M:%S:%f')
print(before_three_days_obj, type(before_three_days_obj))
print('===========================================')
one_hour = timedelta(hours=1)
after_one_hour = now + one_hour
after_one_hour_str = after_one_hour.strftime('%H:%M:%S')
print(after_one_hour_str)
after_one_hour_obj = datetime.strptime(after_one_hour_str, '%H:%M:%S')
print(after_one_hour_obj, type(after_one_hour_obj))
# default_str = '2023 5 28 abc'
# default_obj = datetime.strptime(default_str, '%Y %m %d')
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