Python はマルチスレッド ダウンロードをサポートします。ブレークポイント再開ダウンロードの例

复制代码 代码如下:

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

from __future__ import unicode_literals

from multiprocessing.dummy import Pool as ThreadPool
import threading

import os
import sys
import cPickle
from collections import namedtuple
import urllib2
from urlparse import urlsplit

import time

# global lock
lock = threading.Lock()

# default parameters
defaults = 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 = divmod(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 '%s をダウンロード中' % url
# start Monitor
threading.Thread(target=_monitor, args=(infopath, file_info,blocks)).start()

# ダウンロードを開始
with open(workpath, 'rb+') as fobj:
args = [(url, block[i], fobj,buffer_size) for i in range(len(blocks)) ifブロック[i][1]

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

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

# workpath の名前を出力に変更します
if os.path.exists(output):
os.remove(output)
os.rename(workpath, Output)

# infopath を削除
if os.path.exists(infopath):
os.remove(infopath)

すべてアサート ([ブロック[1]>=ブロック内のブロックのブロック[2]]) が 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:
チャンク = res.read(buffer_size)
チャンクでない場合:
ブレーク
ロックあり:
fobj.seek(block[1])
fobj .write(チャンク)
ブロック[1] += len(チャンク)

def _monitor(infopath, file_info,blocks):
while 1:
with lock:
パーセント = sum([block[1] - block[0] for block in block] ) * 100 / file_info.size
progress(percent)
ifpercent >= 100:
Break
write_data(infopath, (file_info,blocks))
time.sleep(2)

if __name__ == '__main__':
import argparse
parser = argparse.ArgumentParser(description='マルチスレッドでファイルをダウンロードします。')
parser.add_argument('url' , type=str, help='ダウンロード ファイルの URL')
parser.add_argument('-o', type=str,default=None, dest="output", help='出力ファイル')
parser.add_argument('-t', type=int,default=defaults['thread_count'], dest="thread_count", help='ダウンロードまでのスレッド数')
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="ブロックサイズ"、ヘルプ='ブロック サイズ')

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)