response = requests.head(self.url)print(response.headers)#
{'Keep-Alive': 'timeout=5, max=100', 'Accept-Ranges': 'bytes', 'Date': 'Sat, 18 Feb 2017 02:56:08 GMT', 'ETag': '"933e-548c4b0beff53"', 'Content-Type': 'image/jpeg', 'Content-Length': '37694', 'Last-Modified': 'S
at, 18 Feb 2017 02:21:39 GMT', 'Connection': 'Keep-Alive', 'Server': 'Apache/2.4.18 (Ubuntu)'}

        headers = {"Range":"bytes=0-12599"}res = requests.get(self.url,headers=headers)# res.text 是将get获取的byte类型数据自动编码，是str类型， res.content是原始的byte类型数据# 所以下面是直接write(res.content)with open(self.filename,'wb') as f:f.write(res.content)

        headers = {"Range":"bytes=12600-25199"}res = requests.get(self.url,headers=headers)# res.text 是将get获取的byte类型数据自动编码，是str类型， res.content是原始的byte类型数据# 所以下面是直接write(res.content)with open(self.filename,'ab+') as f:print(f.tell())f.write(res.content)

r或rt 默认模式，文本模式读
rb   二进制文件w或wt 文本模式写，打开前文件存储被清空
wb  二进制写，文件存储同样被清空a  追加模式，只能写在文件末尾
a+ 可读写模式，写只能写在文件末尾w+ 可读写，与a+的区别是要清空文件内容
r+ 可读写，与a+的区别是可以写到文件任何位置

        headers = {"Range":"bytes=26000-37694"}res = requests.get(self.url,headers=headers)# res.text 是将get获取的byte类型数据自动编码，是str类型， res.content是原始的byte类型数据# 所以下面是直接write(res.content)with open(self.filename,'rb+') as f:f.seek(26000)f.write(res.content)

#! -coding:utf8 -*-
import threading,sys
import requests
import time
import osclass MulThreadDownload(threading.Thread):def __init__(self,url,startpos,endpos,f):super(MulThreadDownload,self).__init__()self.url = urlself.startpos = startposself.endpos = endposself.fd = fdef download(self):print("start thread:%s at %s" % (self.getName(), time.time()))headers = {"Range":"bytes=%s-%s"%(self.startpos,self.endpos)}res = requests.get(self.url,headers=headers)# res.text 是将get获取的byte类型数据自动编码，是str类型， res.content是原始的byte类型数据# 所以下面是直接write(res.content)
        self.fd.seek(self.startpos)self.fd.write(res.content)print("stop thread:%s at %s" % (self.getName(), time.time()))# f.close()def run(self):self.download()if __name__ == "__main__":url = sys.argv[1]#获取文件的大小和文件名filename = url.split('/')[-1]filesize = int(requests.head(url).headers['Content-Length'])print("%s filesize:%s"%(filename,filesize))#线程数threadnum = 3#信号量，同时只允许3个线程运行
    threading.BoundedSemaphore(threadnum)# 默认3线程现在，也可以通过传参的方式设置线程数step = filesize // threadnummtd_list = []start = 0end = -1# 请空并生成文件tempf = open(filename,'w')tempf.close()# rb+ ，二进制打开，可任意位置读写with open(filename,'rb+') as  f:fileno = f.fileno()# 如果文件大小为11字节，那就是获取文件0-10的位置的数据。如果end = 10，说明数据已经获取完了。while end < filesize -1:start = end +1end = start + step -1if end > filesize:end = filesize# print("start:%s, end:%s"%(start,end))# 复制文件句柄dup = os.dup(fileno)# print(dup)# 打开文件fd = os.fdopen(dup,'rb+',-1)# print(fd)t = MulThreadDownload(url,start,end,fd)t.start()mtd_list.append(t)for i in  mtd_list:i.join()

python multiprocess_download.py http://192.168.10.7/of.tar.gz
of.tar.gz filesize:36578022
start thread:Thread-1 at 1487405833.7353075
start thread:Thread-2 at 1487405833.736311
start thread:Thread-3 at 1487405833.7378094
stop thread:Thread-1 at 1487405836.9561603
stop thread:Thread-3 at 1487405837.0016065
stop thread:Thread-2 at 1487405837.0116146