day 11 - 2 装饰器练习

1、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

FLAG = False
def login(func):
    def inner(*args,**kwargs):
        global FLAG
        if FLAG:
            ret = func(*args,**kwargs)
            return ret
        else:
            #登录程序
            username = input('请输入用户名：')
            password = input('请输入密码：')
            if username == 'ysg' and password == "":
                FLAG = True
                ret = func(*args,**kwargs)
                return ret
            else:
                print("登录失败")
    return inner

@login
def shoplist_add():
    print("向购物车中添加物品")

@login
def shoplist_del():
    print("向购物车中添加物品")

shoplist_add()
shoplist_del()

FLAG = False
def login(f):
    def inner(*args,**kwargs):
        #判断是否以成功登录
        global FLAG
        if FLAG:
            ret = f(*args,**kwargs)
            return
        else:
            #登录验证
            use = input('>>>')
            pwd = input('>>>')
            lis=[]
            with open('E:/py/info.txt','r',encoding='utf-8')as info:
                for i in info:
                   lis.append(i)
            if use == lis[0].strip() and pwd == lis[1].strip():
                print('登陆成功')
                FLAG = True
                ret = f(*args,**kwargs)
                return ret
            else:
                print('登录失败')
    return inner

@login
def shoping():
    print('在购物')
@login
def money():
    print('在支付')

shoping()
money()

2、编写装饰器，为多个函数加上记录调用功能，要求每次调用函数都将被调用的函数名称写入文件

def log(func):
    def inner(*arge,**kwargs):
        with open('E:/py/log/log.txt','a',encoding='utf-8') as f:
            f.write(func.__name__ + '\n')
        ret = func(*arge,**kwargs)
        print("")
        return ret
    return inner

@log
def shoplist_add():
    print("购买了一件商品")

@log
def shoplist_del():
    print("删除了一件商品")

shoplist_add()
shoplist_del()
shoplist_add()
shoplist_del()
shoplist_add()
shoplist_del()

进阶练习：
1.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
2.为题目1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），就优先文件中读取网页内容，否则，就去下载，然后存到文件中

import os
from urllib.request import urlopen
def cache(func):
    def inner(*arge,**kwargs):
        if os.path.getsize('E:/py/log/url.txt'):
            with open ("E:/py/log/url.txt","rb") as f:
                return f.read()
        ret = func(*arge,**kwargs)
        with open('E:/py/log/url.txt','wb') as f:
            f.write(ret+b"*****")
        return ret
    return inner

@cache
def get(url):
    code = urlopen(url).read()
    return code

ret = get('http://www.baidu.com')
print(ret)

ret = get('http://www.baidu.com')
print(ret)