python重试装饰器(Python function retry decorator)

py3study

发布于 2020-03-12 12:28:01

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代码可运行

python重试装饰器(Python function retry decorator)

在用requests请求接口或者html的时候，很容易出现超时，限制等各种原因。

在对源代码不进行修改的情况下，可以用装饰器来进行重试

任何函数：成功，返回-结果，失败，返回--False 都可以用这个装饰器进行重试

1.不需要传参的装饰器写法:

max_retry 为默认重试的次数

import requests


def retry(func):
    def inner(*args, **kwargs):
        ret = func(*args, **kwargs)
        max_retry = 3
        number = 0
        if not ret:
            while number < max_retry:
                number += 1
                print("尝试第:{}次".format(number))
                result = func(*args, **kwargs)
                if result:
                    break
    return inner


@retry
def get_reponse():
    headers = {
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36'
    }
    url = 'https://www.baidu.com'
    try:
        r = requests.get(url=url, headers=headers, timeout=0.01)
        if r.status_code == 200:
            print(r.headers)
            return r.headers
    except requests.exceptions.ReadTimeout:
        return False
    except requests.exceptions.ConnectTimeout:
        return False
    except Exception:
        return False

get_reponse()

执行结果:

尝试第:1次

尝试第:2次

尝试第:3次

2.需要传参的装饰器写法:

def retry(*args, **kwargs):
    def warpp(func):
        def inner():
            ret = func()
            max_retry = kwargs.get('max_retry')
            # 不传默认重试3次
            if not max_retry:
                max_retry = 3
            number = 0
            if not ret:
                while number < max_retry:
                    number += 1
                    print("尝试第:{}次".format(number))
                    result = func()
                    if result:
                        break
        return inner
    return warpp


@retry(max_retry=5)  # 不传默认为3次  @retry() 括号需要带
def get_reponse():
    headers = {
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36'
    }
    url = 'https://www.baidu.com'
    try:
        r = requests.get(url=url, headers=headers, timeout=0.01)
        if r.status_code == 200:
            print(r.headers)
            return r.headers
    except requests.exceptions.ReadTimeout:
        return False
    except requests.exceptions.ConnectTimeout:
        return False
    except Exception:
        return False

get_reponse()

执行结果：

尝试第:1次

尝试第:2次

尝试第:3次

尝试第:4次

尝试第:5次

3. 装饰器在类的用法

import requests

class Test:
    def retry(*args, **kwargs):
        def warpp(func):
            def inner(self, *args, **kwargs):
                ret = func(self, *args, **kwargs)
                max_retry = kwargs.get('max_retry')
                # 不传默认重试3次
                if not max_retry:
                    max_retry = 3
                number = 0
                if not ret:
                    while number < max_retry:
                        number += 1
                        print("尝试第:{}次".format(number))
                        result = func(self, *args, **kwargs)
                        if result:
                            break
            return inner
        return warpp

    @retry()
    def get_reponse(self, url):
        headers = {
            'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.103 Safari/537.36'
        }
        try:
            r = requests.get(url=url, headers=headers, timeout=0.01)
            if r.status_code == 200:
                print(r.headers)
                return r.headers
        except requests.exceptions.ReadTimeout:
            return False
        except requests.exceptions.ConnectTimeout:
            return False
        except Exception:
            return False


if __name__ == '__main__':
    st = Test()
    url = 'https://www.baidu.com'
    st.get_reponse(url)