python爬虫URL重试机制的实现方法(python2.7以及python3.5)

# -*-coding:utf-8-*-"""ayou""" import requests def url_retry(url,num_retries=3): print("access!") try:  request = requests.get(url,timeout=60)  #raise_for_status(),如果不是200会抛出HTTPError错误  request.raise_for_status()  html = request.content except requests.HTTPError as e:  html=None  if num_retries>0:   #如果不是200就重试，每次递减重试次数   return url_retry(url,num_retries-1) #如果url不存在会抛出ConnectionError错误，这个情况不做重试 except requests.exceptions.ConnectionError as e:  return return html url_retry("http://httpbin.org/status/404")

# -*-coding:utf-8-*-"""ayou"""import asyncioimport aiohttp async def print_page(url,num_retries=3): async with aiohttp.ClientSession() as session:  try:   async with session.get(url,timeout=60) as response:    print("access!")     #raise_for_status(),如果不是200会抛出HttpProcessingError错误    response.raise_for_status()    body = await response.text()  except aiohttp.errors.HttpProcessingError as e:   body = None   if num_retries > 0:     #如果不是200就重试，每次递减重试次数    return await print_page(url, num_retries - 1)  #不存在URL会抛出ClientResponseError错误  except aiohttp.errors.ClientResponseError as e:   return e session.close() print(body) return body def main(): #这是一个不存在URL # url = 'http://httpbin.org/status/404111' #这是一个404的URL url = 'http://httpbin.org/status/404' loop = asyncio.get_event_loop() loop.run_until_complete(print_page(url)) loop.close() if __name__ == '__main__': main()

# -*-coding:utf-8-*-"""ayou"""import requests #定义一个重试修饰器，默认重试一次def retry(num_retries=1): #用来接收函数 def wrapper(func):  #用来接收函数的参数  def wrapper(*args,**kwargs):   #为了方便看抛出什么错误定义一个错误变量   last_exception =None   #循环执行包装的函数   for _ in range(num_retries):    try:     #如果没有错误就返回包装的函数，这样跳出循环     return func(*args, **kwargs)    except Exception as e:     #捕捉到错误不要return，不然就不会循环了     last_exception = e   #如果要看抛出错误就可以抛出   # raise last_exception  return wrapper return wrapper if __name__=="__main__": @retry(5) def url_retry(url):  request = requests.get(url, timeout=60)  print("access!")  request.raise_for_status()  html = request.content  print(html)  return html  url_retry("http://httpbin.org/status/404") # url_retry("http://httpbin.org/status/404111") # url_retry("http://www.baidu.com")

# -*-coding:utf-8-*-"""ayou"""import aiohttp,asyncio #定义一个重试修饰器，默认重试一次def retry(num_retries=1): #用来接收函数 def wrapper(func):  #用来接收函数的参数  def wrapper(*args,**kwargs):   #为了方便看抛出什么错误定义一个错误变量   last_exception =None   #循环执行包装的函数   for _ in range(num_retries):    try:     #如果没有错误就返回包装的函数，这样跳出循环     return func(*args, **kwargs)    except Exception as e:     #捕捉到错误不要return，不然就不会循环了     last_exception = e   #如果要看抛出错误就可以抛出   # raise last_exception  return wrapper return wrapper async def print_page(url): async with aiohttp.ClientSession() as session:  async with session.get(url,timeout=60) as response:   print("access!")    #raise_for_status(),如果不是200会抛出HttpProcessingError错误   response.raise_for_status()   body = await response.text() session.close() print(body) return body @retry(5)def loop_get(): # url = "http://www.baidu.com" # url = 'http://httpbin.org/status/404111' url = 'http://httpbin.org/status/404' loop = asyncio.get_event_loop() loop.run_until_complete(print_page(url)) loop.close() if __name__ == '__main__': loop_get()