python file-like Obj
python file-like Obj
官网对文件操作解释：
open(file, mode='r', buffering=-1, encoding=None, errors=None, newline=None, closefd=True, opener=None)
Character | Meaning |
|---|---|
'r' | open for reading (default) |
'w' | open for writing, truncating the file first |
'x' | open for exclusive creation, failing if the file already exists |
'a' | open for writing, appending to the end of the file if it exists |
'b' | binary mode |
't' | text mode (default) |
'+' | open a disk file for updating (reading and writing) |
'U' | universal newlines mode (deprecated) |
The default mode is 'r' (open for reading text, synonym of 'rt'). For binary read-write access, the mode 'w+b' opens and truncates the file to 0 bytes. 'r+b' opens the file without truncation.
https://docs.python.org/3/library/functions.html#open
文本读写操作：open(), close(), read(), readlines(),
一、普通操作，open(),read(),close()
#!/usr/bin/python
#coding=utf-8
import logging
try:
f = open('/home/seeing-zynq/Documents/Temp/Test/mydict.py', 'r')
print f.read();
print 'read'
except Exception as e:
logging.exception(e)
print 'error'
raise
finally:
if f:
f.close()
print 'OK' 运行结果：
#!/usr/bin/python
# -*- coding: utf-8 -*-
class Dict(dict):
def __init__(self, **kw):
super().__init__(**kw)
def __getattr__(self, key):
try:
return self[key]
except KeyError:
raise AttributeError(r"'Dict' object has no attribute '%s'" % key)
def __setattr__(self, key, value):
self[key] = value
read
OK二、read()完后自动close()
with open('/home/seeing-zynq/Documents/Temp/Test/mydict.py', 'r') as f:
print (f.read())运行结果：
#!/usr/bin/python
# -*- coding: utf-8 -*-
class Dict(dict):
def __init__(self, **kw):
super().__init__(**kw)
def __getattr__(self, key):
try:
return self[key]
except KeyError:
raise AttributeError(r"'Dict' object has no attribute '%s'" % key)
def __setattr__(self, key, value):
self[key] = value三、为避免read()未知容量的大文件，保险起见用readlines().
print '------------------------------------'
print '-----------------------------------'
f = open('/home/seeing-zynq/Documents/Temp/Test/mydict.py', 'r')
for line in f.readlines():
print(line.strip()) ##strip会将前面首字符前的空格去掉，造成行句没有缩进
f.close()
print 'over'运行结果：
------------------------------------
-----------------------------------
#!/usr/bin/python
# -*- coding: utf-8 -*-
class Dict(dict):
def __init__(self, **kw):
super().__init__(**kw)
def __getattr__(self, key):
try:
return self[key]
except KeyError:
raise AttributeError(r"'Dict' object has no attribute '%s'" % key)
def __setattr__(self, key, value):
self[key] = value
over四、读二进制文件，如图片，视频等
>>> f = open('/Users/michael/test.jpg', 'rb')
>>> f.read()
b'\xff\xd8\xff\xe1\x00\x18Exif\x00\x00...' # 十六进制表示的字节五、write()
with open('/home/seeing-zynq/Documents/Temp/IO/a.txt', 'w') as f:
f.write('haha')
with open('/home/seeing-zynq/Documents/Temp/IO/a.txt', 'r') as f:
print (f.read())
"file.py" 37L, 758C wri运行结果：
haha
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