本节内容：
pythonbiaozhunku/ target=_blank class=infotextkey>python标准库中目录、文件、字符串等模块的用法。
使用 os.path 模块处理文件名
复制代码 代码示例:
import os
filename = "my/little/pony"
print "using", os.name, "..."
print "split", "=>", os.path.split(filename)
print "splitext", "=>", os.path.splitext(filename)
print "dirname", "=>", os.path.dirname(filename)
print "basename", "=>", os.path.basename(filename)
print "join", "=>", os.path.join(os.path.dirname(filename),
os.path.basename(filename))
using nt ...
split => ('my/little', 'pony')
splitext => ('my/little/pony', '')
dirname => my/little
basename => pony
join => my/littlepony
当前目录和上一级目录
>>> os.pardir
'..'
>>> os.curdir
'.'
使用 os.path 模块检查文件名的特征
复制代码 代码示例:
import os
FILES = (
os.curdir,
"/",
"file",
"/file",
"samples",
"samples/sample.jpg",
"directory/file",
"../directory/file",
"/directory/file"
)
for file in FILES:
print file, "=>",
if os.path.exists(file):
print "EXISTS",
if os.path.isabs(file):
print "ISABS",
if os.path.isdir(file):
print "ISDIR",
if os.path.isfile(file):
print "ISFILE",
if os.path.islink(file):
print "ISLINK",
if os.path.is
linuxjishu/9952.html target=_blank class=infotextkey>mount(file):
print "ISMOUNT",
print
. => EXISTS ISDIR
/ => EXISTS ISABS ISDIR ISMOUNT
file =>
/file => ISABS
samples => EXISTS ISDIR
samples/sample.jpg => EXISTS ISFILE
directory/file =>
../directory/file =>
/directory/file => ISABS
expanduser 函数以与大部分Unix shell相同的方式处理用户名快捷符号(~, 不过在 Windows 下工作不正常),
使用 os.path 模块将用户名插入到文件名
复制代码 代码示例:
import os
print os.path.expanduser("~/.pythonrc")
# /home/effbot/.pythonrc
expandvars 函数将文件名中的环境变量替换为对应值
使用 os.path 替换文件名中的环境变量
复制代码 代码示例:
import os
os.environ["USER"] = "user"
print os.path.expandvars("/home/$USER/config")
print os.path.expandvars("$USER/folders")
/home/user/config
user/folders
列出目录下所有的文件和目录
复制代码 代码示例:
>>> a=[file for file in os.listdir("d:new")]
>>> for i in a:
print i
walk 函数会帮你找出一个目录树下的所有文件. 它的参数依次是目录名, 回调函数, 以及传递给回调函数的数据对象.
使用 os.path 搜索文件系统
复制代码 代码示例:
import os
def callback(arg, directory, files):
for file in files:
print os.path.join(directory, file), repr(arg)
os.path.walk(".", callback, "secret message")
./aifc-example-1.py 'secret message'
./anydbm-example-1.py 'secret message'
./array-example-1.py 'secret message'
...
./samples 'secret message'
./samples/sample.jpg 'secret message'
./samples/sample.txt 'secret message'
./samples/sample.zip 'secret message'
./samples/articles 'secret message'
./samples/articles/article-1.txt 'secret message'
./samples/articles/article-2.txt 'secret message'
...
index 函数会返回一个文件名列表, 你可以直接使用for-in 循环处理文件.
使用 os.listdir 搜索文件系统
复制代码 代码示例:
import os
def index(directory):
# like os.listdir, but traverses directory trees
stack = [directory]
files = []
while stack:
directory = stack.pop()
for file in os.listdir(directory):
fullname = os.path.join(directory, file)
files.append(fullname)
if os.path.isdir(fullname) and not os.path.islink(fullname):
stack.append(fullname)
return files
for file in index("."):
print file
.aifc-example-1.py
.anydbm-example-1.py
.array-example-1.py
...
一次返回一个文件
复制代码 代码示例:
import os
class DirectoryWalker:
# a forward iterator that traverses a directory tree
def _ _init_ _(self, directory):
self.stack = [directory]
self.files = []
self.index = 0
def _ _getitem_ _(self, index):
while 1:
try:
file = self.files[self.index]
self.index = self.index + 1
except IndexError:
# pop next directory from stack
self.directory = self.stack.pop()
self.files = os.listdir(self.directory)
self.index = 0
else:
# got a filename
fullname = os.path.join(self.directory, file)
if os.path.isdir(fullname) and not os.path.islink(fullname):
self.stack.append(fullname)
return fullname
for file in DirectoryWalker("."):
print file
.aifc-example-1.py
.anydbm-example-1.py
.array-example-1.py
...
注意 DirectoryWalker 类并不检查传递给 _ _getitem_ _ 方法的索引值. 这意味着如果你越界访问序列成员(索引数字过大)的话, 这个类将不能正常工作.
下面这个例子它返回文件名和它的 os.stat 属性(一个元组). 这个版本在每个文件上都能节省一次或两次stat 调用( os.path.isdir 和 os.path.islink 内部都使用了 stat ), 并且在一些平台上运行很快.
使用 DirectoryStatWalker 搜索文件系统
复制代码 代码示例:
import os, stat
class DirectoryStatWalker:
# a forward iterator that traverses a directory tree, and
# returns the filename and additional file information
def _ _init_ _(self, directory):
self.stack = [directory]
self.files = []
self.index = 0
def _ _getitem_ _(self, index):
while 1:
try:
file = self.files[self.index]
self.index = self.index + 1
except IndexError:
# pop next directory from stack
self.directory = self.stack.pop()
self.files = os.listdir(self.directory)
self.index = 0
else:
# got a filename
fullname = os.path.join(self.directory, file)
st = os.stat(fullname)
mode = st[stat.ST_MODE]
if stat.S_ISDIR(mode) and not stat.S_ISLNK(mode):
self.stack.append(fullname)
return fullname, st
for file, st in DirectoryStatWalker("."):
print file, st[stat.ST_SIZE]
.aifc-example-1.py 336
.anydbm-example-1.py 244
.array-example-1.py 526
Using the stat Module
?
import stat
import os, time
st = os.stat("samples/sample.txt")
print "mode", "=>", oct(stat.S_IMODE(st[stat.ST_MODE]))
print "type", "=>",
if stat.S_ISDIR(st[stat.ST_MODE]):
print "DIRECTORY",
if stat.S_ISREG(st[stat.ST_MODE]):
print "REGULAR",
if stat.S_ISLNK(st[stat.ST_MODE]):
print "LINK",
print
print "size", "=>", st[stat.ST_SIZE]
print "last acces
sed", "=>", time.ctime(st[stat.ST_ATIME])
print "last modified", "=>", time.ctime(st[stat.ST_MTIME])
print "inode changed", "=>", time.ctime(st[stat.ST_CTIME])
mode => 0664
type => REGULAR
size => 305
last accessed => Sun Oct 10 22:12:30 1999
last modified => Sun Oct 10 18:39:37 1999
inode changed => Sun Oct 10 15:26:38 1999
使用 string 模块
复制代码 代码示例:
import string
text = "Monty Python's Flying Circus"
print "upper", "=>", string.upper(text)
print "lower", "=>", string.lower(text)
print "split", "=>", string.split(text)
print "join", "=>", string.join(string.split(text), "+")
print "replace", "=>", string.replace(text, "Python", "Java")
print "find", "=>", string.find(text, "Python"), string.find(text, "Java")
print "count", "=>", string.count(text, "n")
upper => MONTY PYTHON'S FLYING CIRCUS
lower => monty python's flying circus
split => ['Monty', "Python's", 'Flying', 'Circus']
join => Monty+Python's+Flying+Circus
replace => Monty Java's Flying Circus
find => 6 -1
count => 3
