Python实现分割文件及合并文件的方法

 #!/usr/bin/python ########################################################################## # split a file into a set of parts; join.py puts them back together; # this is a customizable version of the standard unix split command-line # utility; because it is written in Python, it also works on Windows and # can be easily modified; because it exports a function, its logic can # also be imported and reused in other applications; ########################################################################## import sys, os kilobytes = 1024 megabytes = kilobytes * 1000 chunksize = int(1.4 * megabytes)     # default: roughly a floppy def split(fromfile, todir, chunksize=chunksize): if not os.path.exists(todir):     # caller handles errors os.mkdir(todir)       # make dir, read/write parts else: for fname in os.listdir(todir):   # delete any existing files os.remove(os.path.join(todir, fname)) partnum = 0 input = open(fromfile, 'rb')     # use binary mode on Windows while 1:          # eof=empty string from read chunk = input.read(chunksize)    # get next part <= chunksize if not chunk: break partnum = partnum+1 filename = os.path.join(todir, ('part%04d' % partnum)) fileobj = open(filename, 'wb') fileobj.write(chunk) fileobj.close()       # or simply open().write() input.close() assert partnum <= 9999       # join sort fails if 5 digits return partnum if __name__ == '__main__': if len(sys.argv) == 2 and sys.argv[1] == '-help': print 'Use: split.py [file-to-split target-dir [chunksize]]' else: if len(sys.argv) <3: interactive=1 fromfile=raw_input('File to be split? ') # input if clicked todir=raw_input('Directory store part files? else: 0 fromfile, sys.argv[1:3] args in cmdline len(sys.argv)== 4: chunksize absfrom, absto [fromfile, todir]) print 'splitting', 'to', absto, 'by', try: parts=split(fromfile, todir, chunksize) except: 'error during split:' sys.exc_info()[0], sys.exc_info()[1] 'split finished:', parts, 'parts are in', interactive: raw_input('press enter key') pause < pre>

 #!/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