Python实现多线程下载

#!/usr/bin/python
# -*- coding: utf-8 -*-
# filename: paxel.py

'''It is a multi-thread downloading tool

It was developed follow axel.
Author: volans
E-mail: volansw [at] gmail.com
'''

import sys
import os
import time
import urllib
from threading import Thread

local_proxies = {'http': 'http://131.139.58.200:8080'}

class AxelPython(Thread, urllib.FancyURLopener):
'''Multi-thread downloading class.

run() is a vitural method of Thread.
'''
def __init__(self, threadname, url, filename, ranges=0, proxies={}):
Thread.__init__(self, name=threadname)
urllib.FancyURLopener.__init__(self, proxies)
self.name = threadname
self.url = url
self.filename = filename
self.ranges = ranges
self.downloaded = 0

def run(self):
'''vertual function in Thread'''
try:
self.downloaded = os.path.getsize( self.filename )
except OSError:
#print 'never downloaded'
self.downloaded = 0

# rebuild start poind
self.startpoint = self.ranges[0] + self.downloaded

# This part is completed
if self.startpoint >= self.ranges[1]:
print 'Part %s has been downloaded over.' % self.filename
return

self.oneTimeSize = 16384 #16kByte/time
print 'task %s will download from %d to %d' % (self.name, self.startpoint, self.ranges[1])

self.addheader("Range", "bytes=%d-%d" % (self.startpoint, self.ranges[1]))

self.urlhandle = self.open( self.url )

data = self.urlhandle.read( self.oneTimeSize )
while data:
filehandle = open( self.filename, 'ab+' )
filehandle.write( data )
filehandle.close()

self.downloaded += len( data )
#print "%s" % (self.name)
#progress = u'\r...'

data = self.urlhandle.read( self.oneTimeSize )

def GetUrlFileSize(url, proxies={}):
urlHandler = urllib.urlopen( url, proxies=proxies )
headers = urlHandler.info().headers
length = 0
for header in headers:
if header.find('Length') != -1:
length = header.split(':')[-1].strip()
length = int(length)
return length

def SpliteBlocks(totalsize, blocknumber):
blocksize = totalsize/blocknumber
ranges = []
for i in range(0, blocknumber-1):
ranges.append((i*blocksize, i*blocksize +blocksize - 1))
ranges.append(( blocksize*(blocknumber-1), totalsize -1 ))

return ranges
def islive(tasks):
for task in tasks:
if task.isAlive():
return True
return False

def paxel(url, output, blocks=6, proxies=local_proxies):
''' paxel
'''
size = GetUrlFileSize( url, proxies )
ranges = SpliteBlocks( size, blocks )

threadname = [ "thread_%d" % i for i in range(0, blocks) ]
filename = [ "tmpfile_%d" % i for i in range(0, blocks) ]

tasks = []
for i in range(0,blocks):
task = AxelPython( threadname[i], url, filename[i], ranges[i] )
task.setDaemon( True )
task.start()
tasks.append( task )

time.sleep( 2 )
while islive(tasks):
downloaded = sum( [task.downloaded for task in tasks] )
process = downloaded/float(size)*100
show = u'\rFilesize:%d Downloaded:%d Completed:%.2f%%' % (size, downloaded, process)
sys.stdout.write(show)
sys.stdout.flush()
time.sleep( 0.5 )

filehandle = open( output, 'wb+' )
for i in filename:
f = open( i, 'rb' )
filehandle.write( f.read() )
f.close()
try:
os.remove(i)
pass
except:
pass

filehandle.close()

if __name__ == '__main__':
url = "http://www.pygtk.org/dist/pygtk2-tut.pdf"
output = 'pygtk2.pdf'
paxel( url, output, blocks=4, proxies={} )