窗外下著小雨，作為單身程序員的我逛著逛著發(fā)現(xiàn)一篇好東西，來自知乎 你都用 Python 來做什么？的第一個高亮答案。
到上面去看了看，地址都是明文的，得，趕緊開始吧。
下載流式文件，requests庫中請求的stream設(shè)為True就可以啦，文檔在此。
先找一個視頻地址試驗一下：
# -*- coding: utf-8 -*-
import requests
def download_file(url, path):
with requests.get(url, stream=True) as r:
chunk_size = 1024
content_size = int(r.headers['content-length'])
print '下載開始'
with open(path, "wb") as f:
for chunk in r.iter_content(chunk_size=chunk_size):
f.write(chunk)
if __name__ == '__main__':
url = '就在原帖...'
path = '想存哪都行'
download_file(url, path)
遭遇當(dāng)頭一棒：
AttributeError: __exit__
這文檔也會騙人的么！
看樣子是沒有實現(xiàn)上下文需要的__exit__方法。既然只是為了保證要讓r最后close以釋放連接池，那就使用contextlib的closing特性好了：
# -*- coding: utf-8 -*-
import requests
from contextlib import closing
def download_file(url, path):
with closing(requests.get(url, stream=True)) as r:
chunk_size = 1024
content_size = int(r.headers['content-length'])
print '下載開始'
with open(path, "wb") as f:
for chunk in r.iter_content(chunk_size=chunk_size):
f.write(chunk)
程序正常運行了，不過我盯著這文件，怎么大小不見變啊，到底是完成了多少了呢？還是要讓下好的內(nèi)容及時存進硬盤，還能省點內(nèi)存是不是：
# -*- coding: utf-8 -*-
import requests
from contextlib import closing
import os
def download_file(url, path):
with closing(requests.get(url, stream=True)) as r:
chunk_size = 1024
content_size = int(r.headers['content-length'])
print '下載開始'
with open(path, "wb") as f:
for chunk in r.iter_content(chunk_size=chunk_size):
f.write(chunk)
f.flush()
os.fsync(f.fileno())
文件以肉眼可見的速度在增大，真心疼我的硬盤，還是最后一次寫入硬盤吧，程序中記個數(shù)就好了：
def download_file(url, path):
with closing(requests.get(url, stream=True)) as r:
chunk_size = 1024
content_size = int(r.headers['content-length'])
print '下載開始'
with open(path, "wb") as f:
n = 1
for chunk in r.iter_content(chunk_size=chunk_size):
loaded = n*1024.0/content_size
f.write(chunk)
print '已下載{0:%}'.format(loaded)
n += 1
結(jié)果就很直觀了：
已下載2.579129%
已下載2.581255%
已下載2.583382%
已下載2.585508%
心懷遠大理想的我怎么會只滿足于這一個呢，寫個類一起使用吧：
# -*- coding: utf-8 -*-
import requests
from contextlib import closing
import time
def download_file(url, path):
with closing(requests.get(url, stream=True)) as r:
chunk_size = 1024*10
content_size = int(r.headers['content-length'])
print '下載開始'
with open(path, "wb") as f:
p = ProgressData(size = content_size, unit='Kb', block=chunk_size)
for chunk in r.iter_content(chunk_size=chunk_size):
f.write(chunk)
p.output()
class ProgressData(object):
def __init__(self, block,size, unit, file_name='', ):
self.file_name = file_name
self.block = block/1000.0
self.size = size/1000.0
self.unit = unit
self.count = 0
self.start = time.time()
def output(self):
self.end = time.time()
self.count += 1
speed = self.block/(self.end-self.start) if (self.end-self.start)>0 else 0
self.start = time.time()
loaded = self.count*self.block
progress = round(loaded/self.size, 4)
if loaded >= self.size:
print u'%s下載完成\r\n'%self.file_name
else:
print u'{0}下載進度{1:.2f}{2}/{3:.2f}{4} 下載速度{5:.2%} {6:.2f}{7}/s'.\
format(self.file_name, loaded, self.unit,\
self.size, self.unit, progress, speed, self.unit)
print '%50s'%('/'*int((1-progress)*50))
運行：
下載開始
下載進度10.24Kb/120174.05Kb 0.01% 下載速度4.75Kb/s
/////////////////////////////////////////////////
下載進度20.48Kb/120174.05Kb 0.02% 下載速度32.93Kb/s
/////////////////////////////////////////////////
看上去舒服多了。
下面要做的就是多線程同時下載了，主線程生產(chǎn)url放入隊列，下載線程獲取url：
# -*- coding: utf-8 -*-
import requests
from contextlib import closing
import time
import Queue
import hashlib
import threading
import os
def download_file(url, path):
with closing(requests.get(url, stream=True)) as r:
chunk_size = 1024*10
content_size = int(r.headers['content-length'])
if os.path.exists(path) and os.path.getsize(path)>=content_size:
print '已下載'
return
print '下載開始'
with open(path, "wb") as f:
p = ProgressData(size = content_size, unit='Kb', block=chunk_size, file_name=path)
for chunk in r.iter_content(chunk_size=chunk_size):
f.write(chunk)
p.output()
class ProgressData(object):
def __init__(self, block,size, unit, file_name='', ):
self.file_name = file_name
self.block = block/1000.0
self.size = size/1000.0
self.unit = unit
self.count = 0
self.start = time.time()
def output(self):
self.end = time.time()
self.count += 1
speed = self.block/(self.end-self.start) if (self.end-self.start)>0 else 0
self.start = time.time()
loaded = self.count*self.block
progress = round(loaded/self.size, 4)
if loaded >= self.size:
print u'%s下載完成\r\n'%self.file_name
else:
print u'{0}下載進度{1:.2f}{2}/{3:.2f}{4} {5:.2%} 下載速度{6:.2f}{7}/s'.\
format(self.file_name, loaded, self.unit,\
self.size, self.unit, progress, speed, self.unit)
print '%50s'%('/'*int((1-progress)*50))
queue = Queue.Queue()
def run():
while True:
url = queue.get(timeout=100)
if url is None:
print u'全下完啦'
break
h = hashlib.md5()
h.update(url)
name = h.hexdigest()
path = 'e:/download/' + name + '.mp4'
download_file(url, path)
def get_url():
queue.put(None)
if __name__ == '__main__':
get_url()
for i in xrange(4):
t = threading.Thread(target=run)
t.daemon = True
t.start()
加了重復(fù)下載的判斷，至于怎么源源不斷的生產(chǎn)url，諸位摸索吧，保重身體！
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