5.1 Python3 进阶 - 文件操作

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源码

# open() 函数
# 打开文件方式一
fp = open('demo/open_mode', 'r', encoding='utf-8')
print('查看返回对象：', fp)
print('文件是否关闭：', fp.closed)
print('文件的访问模式：', fp.mode)
print('文件名称：', fp.name)

# close()方法：关闭一个已打开的文件，例如：
fp.close()
print('再次查看文件是否关闭：', fp.closed)

# 打开文件方式二：上下文管理机制，with语法
with open('demo/open_mode', 'r', encoding='utf-8') as fp:  # 必须是个可迭代对象，支持上下文
    print('文件是否关闭：', fp.closed)
print('再次查看文件是否关闭：', fp.closed)

# with支持同时对多个文件的上下文进行管理
with open('demo/open_mode') as fp1, open('demo/file_object_function.txt') as fp2:
    print('同时打开两个文件：:', fp1, fp2)

源码

from typing import Iterator

# close()方法
fp = open('demo/open_mode', 'r', encoding='utf-8')
fp.close()
fp.close()
print('属性仍然可以被访问：', fp.name)

# next()方法
with open('demo/file_object_function.txt', 'r', encoding='utf-8') as fp:
    print(next(fp))
    print(fp.__next__())
    print(next(fp))
    print('判断fp对象是否是迭代器：', isinstance(fp, Iterator))

源码

# read()方法
with open('demo/file_object_function.txt', 'r', encoding='utf-8') as fp:
    # print('读取12字节数字符：', fp.read(12))
    print('读取所有字节数：', fp.read())

# readline()方法
with open('demo/file_object_function.txt', 'r', encoding='utf-8') as fp:
    # print('读取50字节数字符：', fp.readline(50))
    print('读取整行所有字节数：', fp.readline())

源码

# readlines()方法
with open('demo/file_object_function.txt', 'r', encoding='utf-8') as fp:
    # print('读取30字节数字符：', fp.readlines(30))
    print('读取整行所有字节数：', fp.readlines())

# 可通过for循环进行迭代
with open('demo/file_object_function.txt', 'r', encoding='utf-8') as fp:
    for n, line in enumerate(fp.readlines()):
        print(f'第{n}行是：', line)

源码

# write()方法：文件打开模式：r+（读写，文件指针将会放在文件的开头）
with open('demo/write_mode_r+', 'r+', encoding='utf-8') as fp:
    # print(fp.read())  # 先读后写
    print('返回值是：', fp.write('5test write\n'))
    fp.write('6test write\n')
    # print(fp.read())  # 先写后读


# 文件打开模式：w+（读写）
with open('demo/write_mode_w+', 'w+', encoding='utf-8') as fp:
    # print(fp.read())  # 先读后写
    fp.write('5test write\n')
    fp.write('6test write\n')
    print(fp.read())  # 先写后读

# 文件打开模式：w（只写）
with open('demo/write_mode_w-', 'w') as fp:
    # print(fp.read())  # 先读后写，读文件报错
    fp.write('1test write\n')

源码

# 文writelines()方法：件打开模式：w（只写）
with open('demo/write_mode_w', 'w') as fp:
    seq1 = ['We', 'are', 'learning', 'writelines', 'function!']
    seq2 = ['\nI', '\nam', '\nfighting!']
    fp.writelines(seq1)
    fp.writelines(seq2)

# 文件打开模式：a+（读写，文件指针会放在文件的末尾）
with open('demo/write_mode_a+', 'a+') as fp:
    seq = ['We', 'are', 'learning', 'writelines', 'function!\n']
    fp.writelines(seq)

源码

"""
.env文件内容如下
# test1

 key1=value1

key2 = value2=
key3 = 'value3='

key4 ="val/ue4="

# test2
  key5 =
key6 = ''
{'key7': 'key7'}
{'key7': 'key7', 'key8': 'key8', 'key9': 'key9'}
key7=key7
key8=key8
key9=key9
"""

# Author:PortosHan
# Datetime:2021/8/24 18:24
# Project:zbcf_python_test_project
"""
功能
1、读取配置文件信息；
2、根据配置文件中key键获取value值；
3、添加配置信息：key=value；
"""
from functools import partial


def get_env_info(path):
    """
    :function: 读取env文件内容
    :param path: 传入文件路径名称
    :return: 
    """
    with open(path) as fp:
        print(fp.read())


def get_env_value(path, key=None):
    """
    :function: 根据key获取value值
    :param path: 传入文件路径名称
    :param key: 传入key键
    :return: 返回value值
    """
    value = None
    if key:
        file_key_value = {}
        with open(path) as fp:
            lines = fp.readlines()
            strip_lines = list(map(lambda x: x.replace('\n', ''), lines))
            for line in strip_lines:
                if not line.strip().startswith('#') and '=' in line:
                    line_key, line_value = line.split('=', 1)
                    line_key = line_key.strip()
                    line_value = line_value.strip().strip("\"'")
                    file_key_value[line_key] = line_value
        # print(file_key_value)
        value = file_key_value[key]
        print(f'{key}的值是：{value}')
    return value


def set_key_value(path, **kwargs):
    """
    :function: 向.env文件中添加key=value形式的数据（默认是追加）
    :param path: 传入文件路径名称
    :param kwargs: 可传入字典类型的值
    :return: 
    """
    for key, value in kwargs.items():
        key_value = key + '=' + value
        with open(path, 'a') as fp:
            fp.write('\n' + key_value)


if __name__ == '__main__':
    # .env配置文件地址（相对路径）
    env_path = 'exercise_1/.env'
    # 1、读取配置文件信息；
    get_env_info(env_path)
    # 2、根据配置文件中key键获取value值；
    get_env_value(env_path, 'key4')
    # 利用偏函数，固定env_path的值
    get_partial_env_value = partial(get_env_value, env_path)
    get_partial_env_value('key4')
    # 3、添加配置信息：key=value；
    set_key_value(env_path, key7='key7', **{'key8': 'key8', 'key9': 'key9'})

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