第一种方法
headers = Dict()
url = 'https://www.baidu.com'
try:
proxies = None
response = requests.get(url, headers=headers, verify=False, proxies=None, timeout=3)
except:
# logdebug('requests failed one time')
try:
proxies = None
response = requests.get(url, headers=headers, verify=False, proxies=None, timeout=3)
except:
# logdebug('requests failed two time')
print('requests failed two time')
总结 ：代码比较冗余，重试try的次数越多，代码行数越多，但是打印日志比较方便
第二种方法
def requestDemo(url，):
headers = Dict()
trytimes = 3 # 重试的次数
for i in range(trytimes):
try:
proxies = None
response = requests.get(url, headers=headers, verify=False, proxies=None, timeout=3)
# 注意此处也可能是302等状态码
if response.status_code == 200:
break
except:
# logdebug(f'requests failed {i}time')
print(f'requests failed {i} time')
总结 ：遍历代码明显比第一个简化了很多，打印日志也方便
第三种方法
def requestDemo(url， times=1):
headers = Dict()
try:
proxies = None
response = requests.get(url, headers=headers, verify=False, proxies=None, timeout=3)
html = response.text()
# todo 此处处理代码正常逻辑
pass
return html
except:
# logdebug(f'requests failed {i}time')
trytimes = 3 # 重试的次数
if times < trytimes:
times += 1
return requestDemo(url， times)
return 'out of maxtimes'
总结 ：迭代 显得比较高大上，中间处理代码时有其它错误照样可以进行重试； 缺点 不太好理解，容易出错，另外try包含的内容过多时，对代码运行速度不利。
第四种方法
@retry(3) # 重试的次数 3
def requestDemo(url):
headers = Dict()
proxies = None
response = requests.get(url, headers=headers, verify=False, proxies=None, timeout=3)
html = response.text()
# todo 此处处理代码正常逻辑
pass
return html
def retry(times):
def wrapper(func):
def inner_wrapper(*args, **kwargs):
i = 0
while i < times:
try:
print(i)
return func(*args, **kwargs)
except:
# 此处打印日志 func.__name__ 为say函数
print("logdebug: {}()".format(func.__name__))
i += 1
return inner_wrapper
return wrapper
总结 ：装饰器优点 多种函数复用，使用十分方便
第五种方法
#!/usr/bin/python
# -*-coding='utf-8' -*-
import requests
import time
import json
from lxml import etree
import warnings
warnings.filterwarnings("ignore")
def get_xiaomi():
try:
# for n in range(5): # 重试5次
# print("第"+str(n)+"次")
for a in range(5): # 重试5次
print(a)
url = "https://www.mi.com/"
headers = {
"Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3",
"Accept-Encoding": "gzip, deflate, br",
"Accept-Language": "zh-CN,zh;q=0.9,en;q=0.8",
"Connection": "keep-alive",
# "Cookie": "xmuuid=XMGUEST-D80D9CE0-910B-11EA-8EE0-3131E8FF9940; Hm_lvt_c3e3e8b3ea48955284516b186acf0f4e=1588929065; XM_agreement=0; pageid=81190ccc4d52f577; lastsource=www.baidu.com; mstuid=1588929065187_5718; log_code=81190ccc4d52f577-e0f893c4337cbe4d|https%3A%2F%2Fwww.mi.com%2F; Hm_lpvt_c3e3e8b3ea48955284516b186acf0f4e=1588929099; mstz=||1156285732.7|||; xm_vistor=1588929065187_5718_1588929065187-1588929100964",
"Host": "www.mi.com",
"Upgrade-Insecure-Requests": "1",
"User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.90 Safari/537.36"
}
response = requests.get(url,headers=headers,timeout=10,verify=False)
html = etree.HTML(response.text)
# print(html)
result = etree.tostring(html)
# print(result)
print(result.decode("utf-8"))
title = html.xpath('//head/title/text()')[0]
print("title==",title)
if "左左" in title:
# print(response.status_code)
# if response.status_code ==200:
break
return title
except:
result = "异常"
return result
if __name__ == '__main__':
print(get_xiaomi())
第六种方法
Python重试模块retrying
# 设置最大重试次数
@retry(stop_max_attempt_number=5)
def get_proxies(self):
r = requests.get('代理地址')
print('正在获取')
raise Exception("异常")
print('获取到最新代理 = %s' % r.text)
params = dict()
if r and r.status_code == 200:
proxy = str(r.content, encoding='utf-8')
params['http'] = 'http://' + proxy
params['https'] = 'https://' + proxy
# 设置方法的最大延迟时间，默认为100毫秒(是执行这个方法重试的总时间)
@retry(stop_max_attempt_number=5,stop_max_delay=50)
# 通过设置为50，我们会发现，任务并没有执行5次才结束！
# 添加每次方法执行之间的等待时间
@retry(stop_max_attempt_number=5,wait_fixed=2000)
# 随机的等待时间
@retry(stop_max_attempt_number=5,wait_random_min=100,wait_random_max=2000)
# 每调用一次增加固定时长
@retry(stop_max_attempt_number=5,wait_incrementing_increment=1000)
# 根据异常重试，先看个简单的例子
def retry_if_io_error(exception):
return isinstance(exception, IOError)
@retry(retry_on_exception=retry_if_io_error)
def read_a_file():
with open("file", "r") as f:
return f.read()
read_a_file函数如果抛出了异常，会去retry_on_exception指向的函数去判断返回的是True还是False，如果是True则运行指定的重试次数后，抛出异常，False的话直接抛出异常。
当时自己测试的时候网上一大堆抄来抄去的，意思是retry_on_exception指定一个函数，函数返回指定异常，会重试，不是异常会退出。真坑人啊！
来看看获取代理的应用(仅仅是为了测试retrying模块)
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