python 多线程下载
#-------------------------------------------------------------------------------
# Name: down
# Purpose:
#
# Author: lqefn
#
# Created: 15-09-2010
# Copyright: (c) lqefn 2010
# Licence:
#-------------------------------------------------------------------------------
from urllib.request import *
from threading import Thread
import os
import time
from datetime import datetime
class DownTask(Thread):
def __init__(self, url, file, start, end):
Thread.__init__(self)
self.url = url
self.startpos = start + file.tell()
self.endpos = end
self.file = file
self.length = self.endpos - self.startpos + 1
self.nread = 0
r = Request(url = self.url)
r.add_header("Range", "bytes=%d-%d"%(self.startpos, self.endpos))
self.con = urlopen(r)
print(self.file.name, "start")
print("need read %d bytes"%self.length)
print(self.con.info().as_string())
def run(self):
if self.startpos >= self.endpos:
print(self.file.name, "is already completed")
return
while self.nread < self.length:
nleft = self.length - self.nread
if nleft > 1024:
d = self.con.read(1024)
else:
d = self.con.read(nleft)
if d:
self.nread += len(d)
self.file.write(d)
self.file.flush()
else:
break
self.file.flush()
self.con.close()
print(self.file.name, "complete len/size:%d/%d, read %d byte"%(self.file.tell(), self.endpos-self.startpos+1, self.nread))
def download(url, nthread = 4, filename = None):
if filename is None:
filename = os.path.split(url)[1]
con = urlopen(url)
print(con.info().as_string())
supp = con.headers.get("Accept-Ranges")
length = int(con.headers.get("Content-length"))
con.close()
if not supp:
nthread = 1
ranges = [0]
isize = length // nthread
for i in range(nthread - 1):
ranges.append((i + 1) * isize)
ranges.append(length)
print("ranges", ranges)
files = []
tasks = []
for i in range(len(ranges) - 1):
file = open("%s_part%d"%(filename, i), "ab+")
files.append(file)
task = DownTask(url, file, ranges[i], ranges[i + 1] - 1)
tasks.append(task)
for t in tasks:
t.start()
while any(map(lambda t:t.isAlive(), tasks)):
nread = sum(map(lambda t:t.nread, tasks))
print("/rcomplete(%%%04.1f) len/size:%d/%d"%(nread * 100.0 / length, nread, length), datetime.now(), end = "", file=sys.stdout)
sys.stdout.flush()
time.sleep(0.5)
for t in tasks:
t.join()
file = open(filename, "wb")
for f in files:
f.seek(0)
file.write(f.read())
f.close()
os.remove(f.name)
补充：Web开发 , Python ,
