Python:文件操作技巧(File operation)(转)

Python:文件操作技巧(File operation)

读写文件

#
! /usr/bin/python

#
 -*- coding: utf8 -*-

spath
=
"
D:/download/baa.txt
"

f
=
open(spath,
"
w
"
) 
#
 Opens file for writing.Creates this file doesn't exist.

f.write(
"
First line 1.\n
"
)
f.writelines(
"
First line 2.
"
)

f.close()

f
=
open(spath,
"
r
"
) 
#
 Opens file for reading

for
 line 
in
 f:
    
print
(
"
每一行的数据是:%s
"
%
line)

f.close()

'''

知识点: 如何读写文件
'''

---

遍历文件夹和文件

import
 os
import
 os.path
#
 os,os.path里包含大多数文件访问的函数,所以要先引入它们.

#
 请按照你的实际情况修改这个路径

rootdir 
=
 
"
d:/download
"

for
 parent, dirnames, filenames 
in
 os.walk(rootdir):
    
#
case 1:

for
 dirname 
in
 dirnames:
        
print
 (
"
parent is:
"
 
+
 parent)
        
print
 (
"
dirname is:
"
 
+
 dirname)
    
#
case 2

for
 filename 
in
 filenames:
        
print
 (
"
parent is:
"
 
+
 parent)
        
print
 (
"
filename with full path :
"
 
+
 os.path.join(parent, filename))

'''
知识点:

* os.walk返回一个三元组.其中dirnames是所有文件夹名字(不包含路径),filenames是所有文件的名字(不包含路径).parent表示父目录.
    * case1 演示了如何遍历所有目录.
    * case2 演示了如何遍历所有文件.
    * os.path.join(dirname,filename) : 将形如"/a/b/c"和"d.java"变成/a/b/c/d.java".
'''

---

分割路径和文件名

import
 os.path
#
常用函数有三种:分隔路径,找出文件名.找出盘符(windows系统),找出文件的扩展名.

#
根据你机器的实际情况修改下面参数.

spath
=
"
D:/download/repository.7z
"

#
 case 1:

p,f
=
os.path.split(spath);
print
(
"
dir is:
"
+
p)
print
(
"
file is:
"
+
f)

#
 case 2:

drv,left
=
os.path.splitdrive(spath);
print
(
"
driver is:
"
+
drv)
print
(
"
left is:
"
+
left)
#
 case 3:

f,ext
=
os.path.splitext(spath);
print
(
"
f is:
"
+
f)
print
(
"
ext is:
"
+
ext)
'''

知识点:    这三个函数都返回二元组.
    * case1 分隔目录和文件名
    * case2 分隔盘符和文件名
    * case3 分隔文件和扩展名
'''

总结:5个函数

• os.walk(spath)
• os.path.split(spath)
• os.path.splitdrive(spath)
• os.path.splitext(spath)
• os.path.join(path1,path2)

---

复制文件

import
 shutil
import
 os
import
 os.path

src
=
"
d:\\download\\test\\myfile1.txt
"

dst
=
"
d:\\download\\test\\myfile2.txt
"

dst2
=
"
d:/download/test/测试文件夹.txt
"

dir1
=
os.path.dirname(src)

print
(
"
dir1 %s
"
%
dir1)

if
(os.path.exists(src)
==
False):
    os.makedirs(dir1)

f1
=
open(src,
"
w
"
)
f1.write(
"
line a\n
"
)
f1.write(
"
line b\n
"
)
f1.close()

shutil.copyfile(src, dst)
shutil.copyfile(src, dst2)
f2
=
open(dst,
"
r
"
)
for
 line 
in
 f2:
    
print
(line)

f2.close()

#
测试复制文件夹树

try
:
    srcDir
=
"
d:/download/test
"

dstDir
=
"
d:/download/test2
"

#
如果dstDir已经存在,那么shutil.copytree方法会报错!

#
这也意味着你不能直接用d:作为目标路径.

shutil.copytree(srcDir, dstDir)
except
 Exception as err:
    
print
 (err)
    
'''

知识点:
    * shutil.copyfile:如何复制文件
    * os.path.exists:如何判断文件夹是否存在
    * shutil.copytree:如何复制目录树    
'''

总结:4个函数

• os.path.dirname(path)
• os.path.exists(path)
• shutil.copyfile(src, dst)
• shutil.copytree(srcDir, dstDir)

---

实战:文件备份小程序

import
 os
import
 shutil
import
 datetime

'''

作用：将目录备份到其他路径。
实际效果：
假设给定目录"/media/data/programmer/project/python" ，
备份路径"/home/diegoyun/backup/“ ，
则会将python目录备份到备份路径下，形如：
/home/diegoyun/backup/yyyymmddHHMMSS/python/xxx/yyy/zzz..

用法:更改这两个参数.
backdir:备份目的地.
copydirs:想要备份的文件夹.
'''

def
 mainLogic():
    
#
add dirs you want to copy

backdir
=
"
d:\\test
"

print
(backdir)

copydirs
=
[]
    copydirs.append(
"
d:\\temp
"
);
    
#
copydirs.append("d:\\test");

print
(
"
Copying files  ===================
"
)
    start
=
datetime.datetime.now()

#
gen a data folder for backup

backdir
=
os.path.join(backdir,start.strftime(
"
%Y-%m-%d
"
))
    
#
print("backdir is:"+backdir)

kc
=
0
    
for
 d 
in
 copydirs:
        kc
=
kc
+
copyFiles(d,backdir)

end
=
datetime.datetime.now()
    
print
(
"
Finished! ===================
"
)
    
print
(
"
Total files : 
"
 
+
 str(kc) )
    
print
(
"
Elapsed time : 
"
 
+
 str((end
-
start).seconds)
+
"
 seconds
"
)

def
 copyFiles(copydir,backdir):
    prefix
=
getPathPrefix(copydir)
    
#
print("prefix is:"+prefix )

i
=
0
    
for
 dirpath,dirnames,filenames 
in
 os.walk(copydir):
        
for
 name 
in
 filenames:
            oldpath
=
os.path.join(dirpath,name)
            newpath
=
omitPrefix(dirpath,prefix)
            
print
(
"
backdir is:
"
+
backdir )           
            newpath
=
os.path.join(backdir,newpath)
            
print
(
"
newpath is:
"
+
newpath)

if
 os.path.exists(newpath)
!=
True:
                os.makedirs(newpath)  
            newpath
=
os.path.join(newpath,name)
            
print
(
"
From:
"
+
oldpath
+
"
 to:
"
+
newpath)
            shutil.copyfile(oldpath,newpath)
            i
=
i
+

return
 i

def
 getPathPrefix(fullpath):
    
#
Giving /media/data/programmer/project/ , get the prefix

#
/media/data/programmer/

l
=
fullpath.split(os.path.sep)
    
#
print(str(l[-1]=="")

if
 l[
-

]
==
""
:
        tmp
=
l[
-

]
    
else
:
        tmp
=
l[
-

]
    
return
 fullpath[0:len(fullpath)
-
len(tmp)
-

]

def
 omitPrefix(fullpath,prefix):
    
#
Giving /media/data/programmer/project/python/tutotial/file/test.py ,

#
and prefix is Giving /media/data/programmer/project/,

#
return path as python/tutotial/file/test.py

return
 fullpath[len(prefix)
+

:]

mainLogic()

---

资源参考:

你可以在这里看到更多的api解释,感谢该作者: http://www.cnpython.org/docs/200/p_119.html