python支持断点续传的多线程下载示例

代码如下:

#! /usr/bin/env python#coding=utf-8

from __future__ import unicode_literals

from multiprocessing.dummy import pool as threadpoolimport threading

import osimport sysimport cpicklefrom collections import namedtupleimport urllib2from urlparse import urlsplit

import time

# global locklock = threading.lock()

# default parametersdefaults = dict(thread_count=10, buffer_size=10*1024, block_size=1000*1024)

def progress(percent, width=50): print “%s %d%%\r” % ((‘%%-%ds’ % width) % (width * percent / 100 * ‘=’), percent), if percent >= 100: print sys.stdout.flush()

def write_data(filepath, data): with open(filepath, ‘wb’) as output: cpickle.dump(data, output)

def read_data(filepath): with open(filepath, ‘rb’) as output: return cpickle.load(output)

fileinfo = namedtuple(‘fileinfo’, ‘url name size lastmodified’)

def get_file_info(url): class headrequest(urllib2.request): def get_method(self): return “head” res = urllib2.urlopen(headrequest(url)) res.read() headers = dict(res.headers) size = int(headers.get(‘content-length’, 0)) lastmodified = headers.get(‘last-modified’, ”) name = none if headers.has_key(‘content-disposition’): name = headers[‘content-disposition’].split(‘filename=’)[1] if name[0] == ‘”‘ or name[0] == “‘”: name = name[1:-1] else: name = os.path.basename(urlsplit(url)[2])

return fileinfo(url, name, size, lastmodified)

def download(url, output, thread_count = defaults[‘thread_count’], buffer_size = defaults[‘buffer_size’], block_size = defaults[‘block_size’]): # get latest file info file_info = get_file_info(url)

# init path if output is none: output = file_info.name workpath = ‘%s.ing’ % output infopath = ‘%s.inf’ % output

# split file to blocks. every block is a array [start, offset, end], # then each greenlet download filepart according to a block, and # update the block’ offset. blocks = []

if os.path.exists(infopath): # load blocks _x, blocks = read_data(infopath) if (_x.url != url or _x.name != file_info.name or _x.lastmodified != file_info.lastmodified): blocks = []

if len(blocks) == 0: # set blocks if block_size > file_info.size: blocks = [[0, 0, file_info.size]] else: block_count, remain = pmod(file_info.size, block_size) blocks = [[i*block_size, i*block_size, (i+1)*block_size-1] for i in range(block_count)] blocks[-1][-1] += remain # create new blank workpath with open(workpath, ‘wb’) as fobj: fobj.write(”)

print ‘downloading %s’ % url # start monitor threading.thread(target=_monitor, args=(infopath, file_info, blocks)).start()

# start downloading with open(workpath, ‘rb+’) as fobj: args = [(url, blocks[i], fobj, buffer_size) for i in range(len(blocks)) if blocks[i][1] < blocks[i][2]]

if thread_count > len(args): thread_count = len(args)

pool = threadpool(thread_count) pool.map(_worker, args) pool.close() pool.join()

# rename workpath to output if os.path.exists(output): os.remove(output) os.rename(workpath, output)

# delete infopath if os.path.exists(infopath): os.remove(infopath)

assert all([block[1]>=block[2] for block in blocks]) is true

def _worker((url, block, fobj, buffer_size)): req = urllib2.request(url) req.headers[‘range’] = ‘bytes=%s-%s’ % (block[1], block[2]) res = urllib2.urlopen(req)

while 1: chunk = res.read(buffer_size) if not chunk: break with lock: fobj.seek(block[1]) fobj.write(chunk) block[1] += len(chunk)

def _monitor(infopath, file_info, blocks): while 1: with lock: percent = sum([block[1] – block[0] for block in blocks]) * 100 / file_info.size progress(percent) if percent >= 100: break write_data(infopath, (file_info, blocks)) time.sleep(2)

if __name__ == ‘__main__’: import argparse parser = argparse.argumentparser(description=’download file by multi-threads.’) parser.add_argument(‘url’, type=str, help=’url of the download file’) parser.add_argument(‘-o’, type=str, default=none, dest=”output”, help=’output file’) parser.add_argument(‘-t’, type=int, default=defaults[‘thread_count’], dest=”thread_count”, help=’thread counts to downloading’) parser.add_argument(‘-b’, type=int, default=defaults[‘buffer_size’], dest=”buffer_size”, help=’buffer size’) parser.add_argument(‘-s’, type=int, default=defaults[‘block_size’], dest=”block_size”, help=’block size’)

argv = sys.argv[1:]

if len(argv) == 0: argv = [‘https://eyes.nasa.gov/eyesproduct/eyes/os/win’]

args = parser.parse_args(argv)

start_time = time.time() download(args.url, args.output, args.thread_count, args.buffer_size, args.block_size) print ‘times: %ds’ % int(time.time()-start_time)