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 \’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)