Python获取下载速度并显示进度条

#!/usr/bin/python3
# -*- coding:utf-8 -*-

import sys
import time
from urllib import request


'''
 urllib.urlretrieve 的回调函数：
def callbackfunc(blocknum, blocksize, totalsize):
    @blocknum:  已经下载的数据块
    @blocksize: 数据块的大小
    @totalsize: 远程文件的大小
'''

def Schedule(blocknum, blocksize, totalsize):
    speed = (blocknum * blocksize) / (time.time() - start_time)
    # speed_str = " Speed: %.2f" % speed
    speed_str = " Speed: %s" % format_size(speed)
    recv_size = blocknum * blocksize
    
    # 设置下载进度条
    f = sys.stdout
    pervent = recv_size / totalsize
    percent_str = "%.2f%%" % (pervent * 100)
    n = round(pervent * 50)
    s = ('#' * n).ljust(50, '-')
    f.write(percent_str.ljust(8, ' ') + '[' + s + ']' + speed_str)
    f.flush()
    # time.sleep(0.1)
    f.write('
')

# 字节bytes转化KMG
def format_size(bytes):
    try:
        bytes = float(bytes)
        kb = bytes / 1024
    except:
        print("传入的字节格式不对")
        return "Error"
    if kb >= 1024:
        M = kb / 1024
        if M >= 1024:
            G = M / 1024
            return "%.3fG" % (G)
        else:
            return "%.3fM" % (M)
    else:
        return "%.3fK" % (kb)

if __name__ == '__main__':
    # print(format_size(1222222222))
    start_time = time.time()
    filename = 'test.data'
    url = 'http://ip:port/path/speed.test'
    request.urlretrieve(url, filename, Schedule)