Python 3 教程二:文件和路径访问[转]

1 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".
'''

 

 

2 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)

 

3 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 + 1
    
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[ - 1 ] == "" :
        tmp
= l[ - 2 ]
    
else :
        tmp
= l[ - 1 ]
    
return  fullpath[0:len(fullpath) - len(tmp) - 1 ]

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) + 1 :]

mainLogic()

 

来自:http://www.cnitblog.com/yunshichen/archive/2009/04/01/55931.html

posted @ 2009-04-09 13:27  aoogur  阅读(477)  评论(0编辑  收藏  举报