python11文件读写模块

将文件的打开和关闭，交给上下文管理工具with去实现。

def read_file():
    """
    读取文件
    :return:
    """
    file_path1 = 'D:\\PycharmProjects\\p1\\text.txt'
    file_path2 = 'D:/PycharmProjects/p1/text.txt'
    #普通读取
    f = open(file_path1,encoding='utf-8')
    #rest = f.read()
    ###############################
    #读取指定的内容
    ###他不会从头开始读取，而是延续上一次读取的位置进行读取
    rest = f.read(10)
    print(rest)
    print("@@@@@@@@@@@@@@@@")
    rest = f.read(20)
    print(rest)
    print("@@@@@@@@@@@@@@@@")
    rest = f.read()
    print(rest)
    ##############################
    f.close()
if __name__ == "__main__":
    read_file()

jieguo :
【发文说明】
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def read_file():
    """
    读取文件
    :return:
    """
    file_path1 = 'D:\\PycharmProjects\\p1\\text1.txt'
    file_path2 = 'D:/PycharmProjects/p1/text1.txt'
    #随机读取
    f = open(file_path1,encoding='utf-8')
    #跳过这么多个字符
    #f.seek(10)
    #print(f.read(5))
    #rest = f.readline()
   # print(rest)
    #print(f.readline())#接着上一次读取继续读取
   # print(f.readline())

    #读取所有的行，返回列表：
    rest = f.readlines()
    print(rest)

    f.close()
if __name__ == "__main__":
    read_file()

jeiguo :
['Process finished with exit code 0\n', 'finished with exit code\n', '\n', 'finished with exit\n', '\n', 'finished with exit code\n']

import random
from datetime import datetime

def w_f():
    """
    写入文件
    :return:
    """
    file_name = 'D:/PycharmProjects/p1/text1.txt'

    f = open(file_name,'w')
    f.write("quanzhiqiang")
    f.write("\n")
    f.write("QQQQ")
    f.close()
def w_m_f():
    file_name = "D:/PycharmProjects/p1/text1.txt"
    with open(file_name,"w",encoding='utf-8') as f:
        l = ["11111","2222222","3333"]
        f.writelines(l)

def w_u_l():
    rest = "用户：{}-访问时间：{}\n".format(random.randint(1000,9999),datetime.now())
    file_name = "write_user_log.txt"
    with open(file_name,"a",encoding="utf-8") as f:
        f.writelines(rest)

def read_and_write():
    """
    先读再写入
    :return:
    """
    file_name = "read_and_write.txt"
    with open(file_name,"r+",encoding="utf-8") as f:
        read_rest = f.read()
        #如果里面没用1,写入一行数据aaa
        #如果有，写入bbb
        if "1" in read_rest:
            f.write("bbb")
        else:
            f.write("aaa")

if __name__ == "__main__":
    read_and_write()

文件的备份：

import  os
class FileBackup(object):
    """
    文本的备份
    """
    def __init__(self,src,dist):
        """
        构造方法
        :param src: 需要备份的文件目录
        :param dist: 备份到的目录
        """
        self.src = src
        self.dist = dist

    def read_files(self):
        """ 读取src的所有文件
        :return:
        """
        ls = os.listdir(self.src)
        print(ls)
        for l in ls:
            self.back_file(l)

    def back_file(self,filename):
        """
        备份
        :param filename: 文件/文件夹的名称
        :return:
        """
        #判断dist是否存在，不存在就创建这个目录
        if not os.path.exists(self.dist):
            os.makedirs(self.dist)
            print("文件夹不存在，已经创建")
        #拼接文件的完整路径
        full_src_path = os.path.join(self.src,filename)
        full_dist_path = os.path.join(self.dist, filename)
        #判断文件是否为我们备份的文件
        if os.path.isfile(full_src_path) and os.path.splitext(full_src_path)[-1].lower() == ".txt":
            print(full_src_path)
            #读取文件内容
            with open(full_dist_path,"w",encoding="utf-8") as f_dist:
                print(">>开始备份  {}".format(filename))
                with open(full_src_path,"r",encoding="utf-8") as f_src:
                    while True:
                        rest = f_src.read(100)
                        if not rest:
                            break
                        f_dist.write(rest)
                    f_dist.flush()
        #把读取的内容写入新的文件
        else:
            print("不存在")

if __name__ == "__main__":
    """
    这样子写通用性不高
    src_path = 'D:\\PycharmProjects\\p1\\src'
    dist_path = 'D:\\PycharmProjects\\p1\\dist'
    """
    base_path = os.path.dirname(os.path.abspath(__file__))
    src_path = os.path.join(base_path,"src")
    dist_path = os.path.join(base_path,"dist")
    print(base_path)
    bak = FileBackup(src_path,dist_path)
    bak.read_files()