Python:文件操作技巧(File operation)

一、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'''

二、遍历文件夹和文件

import  osimport  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".''' 

三、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)

四、复制文件

import  shutilimport  osimport  os.pathsrc = " 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)：把目录名提出来
os.path.exists(path)
shutil.copyfile(src, dst)
shutil.copytree(srcDir, dstDir)

os.mkdir(path, [mode])：path为目录名： 这里有个要求，只能创建一级目录。比如path为 abc/def 则当前目录下必须存在abc 否则失败

os.makedirs(path [,mode])：可以创建多级目录

四、删除

os.remove(path)       删除一个文件，一定是一个文件
os.removedirs(path) 删除一个目录下所有东西
os.rmdir(path)           删除一个目录，而且一定要空，否则os.errer

五、实战:文件备份小程序

import  osimport  shutilimport  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()

【转自：http://www.cnblogs.com/mmix2009/p/3211929.html】