Python文件处理

def open(file, mode=‘r‘, buffering=None, encoding=None, errors=None, newline=None, closefd=True)

#!/usr/bin/env python
# -*- coding:utf-8 -*-

f = open(‘demo‘)
print(f)
f.close()
# <_io.TextIOWrapper name=‘demo‘ mode=‘r‘ encoding=‘UTF-8‘>
#python3默认以可读(r)、‘utf-8‘编码方式打开文件

###===r模式打开文件===
f = open(‘demo.txt‘,mode=‘r‘,encoding=‘utf-8‘)  #文件句柄
data = f.read()
print(data)
f.close()


###===w模式打开文件===
#a.该文件存在
f = open(‘demo.txt‘,mode=‘w‘,encoding=‘utf-8‘)
# data = f.read()   #io.UnsupportedOperation: not readable,不可读
f.close()
#发现使用w打开原有文件，尽管什么都不做，该文件内容已被清空(删除)

###b.该文件不存在
f = open(‘demo1.txt‘,mode=‘w‘,encoding=‘utf-8‘)
f.close()
#不存在则创建该文件


###===a模式打开文件===
f = open(‘demo2.txt‘,mode=‘a‘,encoding=‘utf-8‘)
# data = f.read()   #io.UnsupportedOperation: not readable
f.write(‘这是一首词牌名!‘)
f.close()
#该文件不存在则创建新文件并写入内容，存在则在后面追加内容。

###===b模式打开文件===
# f = open(‘demo2.txt‘,mode=‘b‘,encoding=‘utf-8‘)
# #ValueError: binary mode doesn‘t take an encoding argument

# f = open(‘demo2.txt‘,mode=‘b‘)
#alueError: Must have exactly one of create/read/write/append mode and at most one plus

f = open(‘demo3.txt‘,mode=‘br‘)
data = f.read()
print(data)
f.close()

###===t模式打开文件===
# f = open(‘demo3.txt‘,‘t‘)
#ValueError: Must have exactly one of create/read/write/append mode and at most one plus

f = open(‘demo3.txt‘,‘tr‘)
data = f.read()
print(data)
f.close()

###===x模式打开文件===
# 如果文件存在则报错：FileExistsError: [Errno 17] File exists: ‘demo4.txt‘
f = open(‘demo41.txt‘,mode=‘x‘,encoding=‘utf-8‘)
f.write(‘人生苦短，我用python‘)
f.close()

###===+模式打开文件===
# f = open(‘demo4.txt‘,‘+‘)
#ValueError: Must have exactly one of create/read/write/append mode and at most one plus

#+需要和a/r/w/x结合使用,并且添加追加功能，即写文件不删除原内容
f = open(‘demo4.txt‘,‘r+‘)
data = f.read()
print(data)
f.write("人生苦短，我用python")    #不删除原有内容
f.close()

###===U模式打开文件===
f = open(‘demo5.txt‘,‘U‘)
# f.write(‘hello‘)    #io.UnsupportedOperation: not writable不可写
print(f.readlines())    #[‘adcdefg\n‘, ‘    dsfsdfs\n‘, ‘hijklmn‘]
f.close()

#打开一个文件
with open(‘demo‘,‘r‘,encoding=‘utf-8‘) as f:
    print(f.read())
#连续打开两个文件
with open(‘demo1.txt‘,‘r‘,encoding=‘utf-8‘) as f1,open(‘demo2.txt‘,‘r‘,encoding=‘utf-8‘) as f2:
    print(f1.read(),f2.read())

#Read at most size bytes, returned as bytes.
f = open(‘demo‘,mode=‘r‘,encoding=‘utf-8‘)
data = f.read()
print(data)
f.close()

f = open(‘demo.txt‘,mode=‘r‘,encoding=‘utf-8‘)
data = f.read(5)    #读取文件前5个字节
print(data)
f.close()

f = open(‘demo‘,mode=‘r‘,encoding=‘utf-8‘)
while True:
    line = f.readline()
    if line:
        print(line.strip())
    else:
        print(line)     #空
        print(bool(line))   #False
        break

f = open(‘demo‘,mode=‘r‘,encoding=‘utf-8‘)
while True:
    line = f.readline(8)
    if line:
        print(line.strip())
    else:
        break


‘‘‘
###################demo文件内容##############
伫倚危楼风细细。
望极春愁，黯黯生天际。
草色烟光残照里。无言谁会凭阑意。

拟把疏狂图一醉。
对酒当歌，强乐还无味。
衣带渐宽终不悔。为伊消得人憔悴。
#########################################
运行结果：
伫倚危楼风细细。

望极春愁，黯黯生
天际。
草色烟光残照里。
无言谁会凭阑意。


拟把疏狂图一醉。

对酒当歌，强乐还
无味。
衣带渐宽终不悔。
为伊消得人憔悴。
‘‘‘

f = open(‘demo‘,‘r‘)
lines = f.readlines()
print(lines)
print(type(lines))    #返回的是一个列表<class ‘list‘>
for line in lines:
    print(line.strip())
f.close()

    def write(self, s):
        """Write the unicode string s to the stream and return the number of
        characters written.

        :type b: unicode
        :rtype: int
        """
        return 0


    def writelines(self, lines):
        """Write a list of lines to the stream.

        :type lines: collections.Iterable[unicode]
        :rtype: None
        """
        pass

f = open(‘demo‘,‘a+‘)
print(f.write(‘\n这是一首词牌名‘))
f.close()

l = [‘a‘,‘b‘,‘c‘,‘1‘,‘2‘,‘3‘]
f = open(‘demo‘,‘a+‘)
f.writelines(l)     #写入内容：abcabc123
f.close()

    def close(self, *args, **kwargs): # real signature unknown
        """
        Flush and close the IO object.
        
        This method has no effect if the file is already closed.
        """
        pass
#刷新并关闭文件
f = open(‘a.txt‘,‘a+‘,encoding=‘utf-8‘)
f.write(‘hello‘)
f.close()
	
	

    def fileno(self, *args, **kwargs): # real signature unknown
        """
        Returns underlying file descriptor if one exists.
        
        OSError is raised if the IO object does not use a file descriptor.
        """
        pass
#文件描述符
f = open(‘a.txt‘,‘r‘,encoding=‘utf-8‘)
print(f.fileno())
f.close()



    def flush(self, *args, **kwargs): # real signature unknown
        """
        Flush write buffers, if applicable.
        
        This is not implemented for read-only and non-blocking streams.
        """
        pass
# 刷新文件内部缓冲区
f = open(‘a.txt‘,‘a+‘,encoding=‘utf-8‘)
print(f.fileno())
f.write("JJJJJJJJJJJJJJJJJJ")
f.flush()
input = input("wait for input:")
f.close()



    def isatty(self, *args, **kwargs): # real signature unknown
        """
        Return whether this is an ‘interactive‘ stream.
        
        Return False if it can‘t be determined.
        """
        pass
#判断文件是不是tty设备
f = open(‘a.txt‘,‘r‘,encoding=‘utf-8‘)
print(f.isatty())
f.close()



    def readable(self, *args, **kwargs): # real signature unknown
        """
        Return whether object was opened for reading.
        
        If False, read() will raise OSError.
        """
        pass
#判断文件是否可读
f = open(‘a.txt‘,‘w‘,encoding=‘utf-8‘)
print(f.readable()) #False，因为使用w模式不可读
f.close()



    def seek(self, *args, **kwargs): # real signature unknown
        """
        Change stream position.
        
        Change the stream position to the given byte offset. The offset is
        interpreted relative to the position indicated by whence.  Values
        for whence are:
        
        * 0 -- start of stream (the default); offset should be zero or positive
        * 1 -- current stream position; offset may be negative
        * 2 -- end of stream; offset is usually negative
        
        Return the new absolute position.
        """
        pass
#把文件的指针移动到一个新的位置。
#格式：seek(offset[,whence]),offset表示相对于whence的位置。whence用于设置相对位置的起点，如果whence省略，offset表示相对文件开头的位置。
#0表示从文件开头开始计算。
#1表示从当前位置开始计算。
#2表示从文件末尾开始计算。
f = open(‘a.txt‘,‘r‘,encoding=‘utf-8‘)
print(f.read(2))    
print(f.tell())
f.seek(0)
print(f.read(3))
f.close()



    def seekable(self, *args, **kwargs): # real signature unknown
        """
        Return whether object supports random access.
        
        If False, seek(), tell() and truncate() will raise OSError.
        This method may need to do a test seek().
        """
        pass
#判断指针是否操作
f = open(‘a.txt‘,‘r‘,encoding=‘utf-8‘)
print(f.seekable())
f.close()



    def tell(self, *args, **kwargs): # real signature unknown
        """ Return current stream position. """
        pass
#返回指针位置
f = open(‘a.txt‘,‘r‘,encoding=‘utf-8‘)
f.read(2)
print(f.tell())	#2
f.close()



    def truncate(self, *args, **kwargs): # real signature unknown
        """
        Truncate file to size bytes.
        
        File pointer is left unchanged.  Size defaults to the current IO
        position as reported by tell().  Returns the new size.
        """
        pass
#截断数据
f = open(‘a.txt‘,‘r+‘,encoding=‘utf-8‘)
f.truncate()    #不加参数文件清空
f.close()
#加参数，从文件开头截取
f = open(‘a.txt‘,‘r+‘,encoding=‘utf-8‘)
f.truncate(4)   #截取文件前面4个字节
f.close()



    def writable(self, *args, **kwargs): # real signature unknown
        """
        Return whether object was opened for writing.
        
        If False, write() will raise OSError.
        """
        pass
#判断文件是否可写
f = open(‘a.txt‘,‘r‘,encoding=‘utf-8‘)
print(f.writable()) #False，因为是用r模式打开
f.close()

import os
if os.path.exists(‘test.txt‘):
    os.remove(‘test.txt‘)

#边读边写
f = open(‘a.txt‘,‘r‘,encoding=‘utf-8‘)
f_new = open(‘a_new.txt‘,‘w‘,encoding=‘utf-8‘)
for line in f:
    f_new.write(line)
f.close()
f_new.close()

#或者先全部读取，然后再写
f = open(‘a.txt‘,‘r‘,encoding=‘utf-8‘)
f_new = open(‘a_new.txt‘,‘w‘,encoding=‘utf-8‘)
src = f.read()
f_new.write(src)
f.close()
f_new.close()

import shutil

shutil.copyfile(‘a.txt‘,‘a1.txt‘)

import os

li = os.listdir(‘.‘)
print(li)   #返回一个文件列表
if ‘a1.txt‘ in li:  #判断文件是否存在
    os.rename(‘a1.txt‘,‘A1.txt‘)

import os

#将a.doc修改为a.html
f_list = os.listdir(‘.‘)
print(f_list)   #f_list是一个文件列表，如[‘a.doc‘, ‘b.txt‘, ‘c.txt‘]
for f_name in f_list:   #循环该列吧
    p = f_name.find(‘.‘)    #查找每个元素(字符串).的位置，如a.doc的位置是1。
    print(p)
    print(f_name)   #a.doc
    if f_name[p+1:] == ‘doc‘:   #截取.后面的所有字符，如果是doc
        new_name = f_name[:p+1]+‘html‘  #则截取.和.前面的字符串加上html，即新字符串为a.html
        os.rename(f_name,new_name)  #将新名字重命名给旧文件上面

import os
f_list = os.listdir(‘.‘)
for f_name in f_list:
    li = os.path.splitext(f_name)　　#以.截取，如(‘a‘, ‘.doc‘)
    print(li)
    if li[1] == ‘.doc‘:
        new_name = li[0]+‘.html‘
        os.rename(f_name,new_name)