如何使用请求衡量下载速度和进度？

Question

我正在requests下载文件，但是对于大文件，我每次都需要检查磁盘上文件的大小，因为我无法以百分比形式显示进度，并且我也想知道下载速度。我该怎么做呢？这是我的代码：

import requests
import sys
import time
import os

def downloadFile(url, directory) :
  localFilename = url.split('/')[-1]
  r = requests.get(url, stream=True)

  start = time.clock()
  f = open(directory + '/' + localFilename, 'wb')
  for chunk in r.iter_content(chunk_size = 512 * 1024) :
        if chunk :
              f.write(chunk)
              f.flush()
              os.fsync(f.fileno())
  f.close()
  return (time.clock() - start)

def main() :
  if len(sys.argv) > 1 :
        url = sys.argv[1]
  else :
        url = raw_input("Enter the URL : ")
  directory = raw_input("Where would you want to save the file ?")

  time_elapsed = downloadFile(url, directory)
  print "Download complete..."
  print "Time Elapsed: " + time_elapsed


if __name__ == "__main__" :
  main()

我认为一种方法是在for循环中每次读取文件并根据标头计算进度百分比Content- Length。但是对于大文件（大约500MB），这将再次成为问题。还有其他方法吗？

Answer 1

参见此处：Python进度栏和下载

我认为代码将是这样，它应该显示 自开始以来 的 平均速度， 以每秒字节数为单位：

import requests
import sys
import time

def downloadFile(url, directory) :
  localFilename = url.split('/')[-1]
  with open(directory + '/' + localFilename, 'wb') as f:
    start = time.clock()
    r = requests.get(url, stream=True)
    total_length = r.headers.get('content-length')
    dl = 0
    if total_length is None: # no content length header
      f.write(r.content)
    else:
      for chunk in r.iter_content(1024):
        dl += len(chunk)
        f.write(chunk)
        done = int(50 * dl / total_length)
        sys.stdout.write("\r[%s%s] %s bps" % ('=' * done, ' ' * (50-done), dl//(time.clock() - start)))
        print ''
  return (time.clock() - start)

def main() :
  if len(sys.argv) > 1 :
        url = sys.argv[1]
  else :
        url = raw_input("Enter the URL : ")
  directory = raw_input("Where would you want to save the file ?")

  time_elapsed = downloadFile(url, directory)
  print "Download complete..."
  print "Time Elapsed: " + time_elapsed


if __name__ == "__main__" :
  main()