python生成器/yield协程/gevent写简单的图片下载器功能示例

本文实例讲述了python生成器/yield协程/gevent写简单的图片下载器功能。分享给大家供大家参

本文实例讲述了python生成器/yield协程/gevent写简单的图片下载器功能。分享给大家供大家参考，具体如下：

1、生成器：

'''第二种生成器'''
# 函数只有有yield存在就是生成器
def test(i):
 while True:
 i += 1
 res = yield i
 print(res)
 i += 1
 return res
def main():
 t = test(1) # 创建生成器对象
 print(next(t)) # next第一次执行从上到下，yield是终点
 print(next(t))
 print(t.send(5))
if __name__ == '__main__':
 main()

运行结果：

2 None 4 5 6

2、yield协程demo:

def run1():
 while True:
 print('run1____')
 yield
def run2():
 while True:
 print('run2____')
 yield
def main():
 while True:
 next(run1())
 next(run2())
if __name__ == '__main__':
 main()

3、gevent写简单的下载图片

import gevent
import requests,lxml
# from gevent import monkey
# monkey.patch_all()
def get_pic(url, list):
 headers = {
 'user-agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36'
 }
 response = requests.get(url, headers=headers)
 with open('./pic/'+str(list.pop(0)) + '.png', 'wb') as f:
 f.write(response.content)
def get_pic_name_list():
def main():
 get_pic_name_list()
 list = [x for x in range(9999)]
 gevent.joinall([
 gevent.spawn(get_pic, 'http://pic8.iqiyipic.com/image/20181008/eb/af/v_116880780_m_601_m11_180_236.jpg', list),
 gevent.spawn(get_pic, 'http://pic6.iqiyipic.com/image/20181004/a2/2b/v_112874372_m_601_m15_180_236.jpg', list)
 ])
if __name__ == '__main__':
 main()