import threadingimport requestsimport timeimport osclass Mythread(threading.Thread): def __init__(self,url,startpos,endpos,f): super(Mythread,self).__init__() self.url=url self.startpos=startpos self.endpos=endpos self.fd=f def 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) self.fd.seek(self.startpos) self.fd.write(res.content) print('Stop thread:%s at%s'%(self.getName(),time.time())) self.fd.close() def run(self): self.download()if __name__=="__main__": url='http://www.wendangxiazai.com/word/b-cfbdc77931b765ce050814a9-1.doc' filename=url.split('/')[-1] filesize=int(requests.head(url).headers['Content-Length']) print('%s filesize:%s'%(filename,filesize)) threadnum=3 threading.BoundedSemaphore(threadnum)#允许线程个数 step=filesize//threadnum mtd_list=[] start=0 end=-1 tempf = open('E:/Python/py/web'+filename,'w') tempf.close() mtd_list=[] with open('E:/Python/py/web'+filename,'rb+')as f: #获得文件句柄 fileno=f.fileno()#返回一个整型的文件描述符，可用于底层操作系统的 I/O 操作 while end<filesize-1: start=end+1 end=start+step-1 if end>filesize: end=filesize print ('Start:%s,end:%s'%(start,end)) dup=os.dup(fileno)#复制文件句柄 fd=os.fdopen(dup,'rb+',-1) t=Mythread(url,start,end,fd) t.start() mtd_list.append(t) for i in mtd_list: i.join() f.close() 
