python 实现多线程下载视频的代码

def thread(url):  r = requests.get(url, headers=None, stream=True, timeout=30)  # print(r.status_code, r.headers)  headers = {}  all_thread = 1  # 获取视频大小  file_size = int(r.headers['content-length'])  # 如果获取到文件大小，创建一个和需要下载文件一样大小的文件  if file_size:    fp = open('2.mp4', 'wb')    fp.truncate(file_size)    print('视频大小：' + str(int(file_size / 1024 / 1024)) + "MB")    fp.close()  # 每个线程每次下载大小为5M  size = 5242880  # 当前文件大小需大于5M  if file_size > size:    # 获取总线程数    all_thread = int(file_size / size)    # 设最大线程数为10，如总线程数大于10    # 线程数为10    if all_thread > 10:      all_thread = 10  part = file_size // all_thread  threads = []  starttime = datetime.datetime.now().replace(microsecond=0)  for i in range(all_thread):    # 获取每个线程开始时的文件位置    start = part * i    # 获取每个文件结束位置    if i == all_thread - 1:      end = file_size    else:      end = start + part    if i > 0:      start += 1    headers = headers.copy()    headers['Range'] = "bytes=%s-%s" % (start, end)    t = threading.Thread(target=Handler, name='th-' + str(i),               kwargs={'start': start, 'end': end, 'url': url, 'filename': '2.mp4', 'headers': headers})    t.setDaemon(True)    threads.append(t)  # 线程开始  for t in threads:    time.sleep(0.2)    t.start()  # 等待所有线程结束  for t in threads:    t.join()  endtime = datetime.datetime.now().replace(microsecond=0)  print('用时：%s' % (endtime - starttime))def Handler(start, end, url, filename, headers={}):  tt_name = threading.current_thread().getName()  print(tt_name + ' is begin')  r = requests.get(url, headers=headers, stream=True)  total_size = end - start  downsize = 0  startTime = time.time()  with open(filename, 'r+b') as fp:    fp.seek(start)    var = fp.tell()    for chunk in r.iter_content(204800):      if chunk:        fp.write(chunk)        downsize += len(chunk)        line = tt_name + '-downloading %d KB/s - %.2f MB， 共 %.2f MB'        line = line % (          downsize / 1024 / (time.time() - startTime), downsize / 1024 / 1024,          total_size / 1024 / 1024)        print(line, end='/r')if __name__ == '__main__':  url = input('输入视频链接（请输入视频原链）：')  thread(url)