# 一：编写函数，（函数执行的时间是随机的）
# import time
#
#
# def timmer(func):
# def wrapper(*args, **kwargs):
# start = time.time()
# func(*args, **kwargs)
# stop = time.time()
# print(‘执行时间是%s‘ % (stop - start))
#
# return wrapper
#
#
# @timmer
# def exe():
# print(‘你瞅啥！‘)
#
#
# exe()
# 二：编写装饰器，为函数加上统计时间的功能
# import time
# def a(func):
# def inner():
# start = time.time()
# func()
# print(time.time() - start)
# return inner
# @a
# def index():
# print(‘welcome‘)
# time.sleep(2)
# index()
# 三：编写装饰器，为函数加上认证的功能
# flag = 0
#
#
# def login(func):
# def inner():
# global flag
# if flag == 0:
# username = ‘egon‘
# password = ‘123‘
# username_input = input(‘请输入用户名：‘).strip()
# pwd = input(‘请输入密码：‘).strip()
# if username_input == username and pwd == password:
# print(‘登录成功！‘)
# flag = 1
# else:
# print(‘用户名或密码错误！‘)
# if flag == 1:
# func()
# return inner
#
#
# @login
# def america():
# print(‘welcome to america‘)
# america()
# 四：编写装饰器，为多个函数加上认证的功能（用户的账号密码来源于文件），要求登录成功一次，后续的函数都无需再输入用户名和密码
# 注意：从文件中读出字符串形式的字典，可以用eval(‘{"name":"egon","password":"123"}‘)转成字典格式
# flag = 0
#
#
# def login(func):
# def inner():
# global flag
# while flag == 0:
# with open(‘usermessage_db.txt‘, ‘r‘)as f:
# data = f.read()
# dic1 = eval(data)
# username_input = input(‘请输入用户名：‘).strip()
# pwd = input(‘请输入密码：‘).strip()
# if username_input in dic1 and pwd == dic1[username_input]:
# print(‘登录成功！‘)
# flag = 1
# else:
# print(‘用户名或密码错误！‘)
# if flag == 1:
# func()
# return inner
#
#
# def china():
# print(‘welcome to china‘)
#
#
# @login
# def america():
# print(‘welcome to america‘)
#
#
# @login
# def japan():
# print(‘welcome to japan‘)
# china()
# america()
# japan()
#
# 五：编写装饰器，为多个函数加上认证功能，要求登录成功一次，在超时时间内无需重复登录，超过了超时时间，则必须重新登录
# import time
# flag = 0
#
#
# def login(func):
# def inner():
# global flag
# while flag == 0:
# with open(‘usermessage_db.txt‘, ‘r‘)as f:
# data = f.read()
# dic1 = eval(data)
# username_input = input(‘请输入用户名：‘).strip()
# pwd = input(‘请输入密码：‘).strip()
# if username_input in dic1 and pwd == dic1[username_input]:
# print(‘登录成功！‘)
# flag = 1
# else:
# print(‘用户名或密码错误！‘)
# if flag == 1:
# func()
# return inner
#
#
# def wait(func):
# def inner():
# global flag
# if flag == 1:
# start = time.time()
# func()
# end = time.time()
# if end - start > 5:
# flag = 0
# print(‘登录已超时！‘)
# return inner
#
#
# def china():
# print(‘welcome to china‘)
#
#
# @login
# @wait
# def america():
# print(‘welcome to america‘)
#
#
# @login
# @wait
# def japan():
# print(‘welcome to japan‘)
# time.sleep(5)
#
# china()
# america()
# japan()
# america()
#
# 六：编写下载网页内容的函数，要求功能是：用户传入一个url，函数返回下载页面的结果
# import requests
#
#
# def down():
# url = input(‘请输入网址：‘)
# r = requests.get(url)
# r.raise_for_status()
# print(r.text)
# down()
# 七：为题目五编写装饰器，实现缓存网页内容的功能：
# 具体：实现下载的页面存放于文件中，如果文件内有值（文件大小不为0），就优先从文件中读取网页内容，否则，就去下载，然后存到文件中
# import requests
# import os
# url = ‘http://www.baidu.com‘
#
#
# def out(func):
# def inner(*args, **kwargs):
# if not os.path.exists(‘r.txt‘):
# with open(‘r.txt‘, ‘w‘):
# pass
# if os.path.getsize(‘r.txt‘):
# with open(‘r.txt‘, ‘r‘, encoding=‘utf-8‘) as f:
# res = f.read()
# else:
# res = func(*args, **kwargs)
# with open(‘r.txt‘, ‘w‘, encoding=‘utf-8‘) as f:
# f.write(res)
# print(‘文件缓存成功！‘)
# return inner
#
#
# @out
# def get(urls):
# return requests.get(urls).text
# get(url)
# 扩展功能：用户可以选择缓存介质/缓存引擎，针对不同的url，缓存到不同的文件中
# import requests
# import os
#
# settings = [‘file‘, ‘db‘, ‘redis‘]
# url = input(‘请输入网址：‘).strip()
# while 1:
# sets = input(‘请输入缓存介质(file/db/redis)：‘)
# if sets not in settings:
# print(‘输入有误，请重试！‘)
# continue
# else:
# print(‘通过%s来缓存‘ % sets)
# break
#
#
# def out2(urls, setting=‘file‘):
# def out(func):
# def inner(*args, **kwargs):
# if sets == ‘file‘:
# if not os.path.exists(‘r.txt‘):
# print(‘文件不存在‘)
# with open(‘r.txt‘, ‘w‘):
# pass
# if os.path.getsize(‘r.txt‘):
# with open(‘r.txt‘, ‘r‘, encoding=‘utf-8‘) as f:
# res = f.read().strip()
# else:
# res = func(*args, **kwargs)
# with open(‘r.txt‘, ‘w‘, encoding=‘utf-8‘) as f:
# f.write(res)
# print(‘文件缓存成功！‘)
# elif sets == ‘db‘:
# print(‘db!没学！‘)
# elif sets == ‘redis‘:
# print(‘redis!没学！‘)
#
# return inner
#
# return out
#
#
# @out2(url, sets)
# def download(urls, setting):
# data = requests.get(urls).text
# return data
#
#
# download(url, sets)
# 八：还记得我们用函数对象的概念，制作一个函数字典的操作吗，来来来，我们有更高大上的做法，在文件开头声明一个空字典，然后在每个函数前加上装饰器，完成自动添加到字典的操作
# from functools import wraps
# dic1 = {}
#
#
# def out(func):
# @wraps(func)
# def inner(*args, **kwargs):
# func(*args, **kwargs)
# dic1[func.__name__] = func(*args, **kwargs)
# return inner
#
#
# @out
# def add(x, y):
# return x + y
#
#
# @out
# def sub(x, y):
# return x - y
#
# add(5, 6)
# print(dic1)
# sub(8, 2)
# print(dic1)
# 九 编写日志装饰器，实现功能如：一旦函数f1执行，则将消息2017-07-21 11:12:11 f1 run写入到日志文件中，日志文件路径可以指定
# 注意：时间格式的获取
# import time
# time.strftime(‘%Y-%m-%d %X‘)
# import time
# url = input(‘请输入需要写入的文件路径：‘).strip()
#
#
# def out(func):
# def inner(*args, **kwargs):
# func(*args, **kwargs)
# times = time.strftime(‘%Y-%m-%d %X‘)
# with open(url, ‘a‘)as f:
# f.write(‘%s %s run\n‘ % (times, func.__name__))
# return inner
#
#
# @out
# def f1():
# print(‘Hello world!‘)
#
#
# @out
# def f2():
# print(‘Hello Shanghai‘)
# f1()
# f2()
# f1()
原文：https://www.cnblogs.com/DariusZhou/p/9714339.html