python分割文件的常用方法(3)

#!/usr/bin/python
##########################################################################
# join all part files in a dir created by split.py, to recreate file. 
# This is roughly like a 'cat fromdir/* > tofile' command on unix, but is
# more portable and configurable, and exports the join operation as a
# reusable function.  Relies on sort order of file names: must be same
# length.  Could extend split/join to popup Tkinter file selectors.
##########################################################################
     
import os, sys
readsize = 1024
     
def join(fromdir, tofile):
    output = open(tofile, 'wb')
    parts  = os.listdir(fromdir)
    parts.sort()
    for filename in parts:
filepath = os.path.join(fromdir, filename)
fileobj  = open(filepath, 'rb')
while 1:
    filebytes = fileobj.read(readsize)
    if not filebytes: break
    output.write(filebytes)
fileobj.close()
    output.close()
     
if __name__ == '__main__':
    if len(sys.argv) == 2 and sys.argv[1] == '-help':
print 'Use: join.py [from-dir-name to-file-name]'
    else:
if len(sys.argv) != 3:
    interactive = 1
    fromdir = raw_input('Directory containing part files? ')
    tofile  = raw_input('Name of file to be recreated? ')
else:
    interactive = 0
    fromdir, tofile = sys.argv[1:]
absfrom, absto = map(os.path.abspath, [fromdir, tofile])
print 'Joining', absfrom, 'to make', absto
     
try:
    join(fromdir, tofile)
except:
    print 'Error joining files:'
    print sys.exc_info()[0], sys.exc_info()[1]
else:
   print 'Join complete: see', absto
if interactive: raw_input('Press Enter key') # pause if clicked