Python_装饰器习题_31

# 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

        '''登录程序'''

        if FLAG:

            ret = func(*args, **kwargs)  # func是被装饰的函数

            return ret

        else:

            username = input('username : ')

            password = input('password : ')

            if username == 'boss_gold' and password == '':

                FLAG = True

                ret = func(*args,**kwargs)      #func是被装饰的函数

                return ret

            else:

                print('登录失败')

    return inner

@login

def shoplist_add():

    print('增加一件物品')

@login

def shoplist_del():

    print('删除一件物品')

shoplist_add()

shoplist_del()

def log(func):

    def inner(*args,**kwargs):

        with open('log','a',encoding='utf-8') as f:

            f.write(func.__name__+'\n')

        ret = func(*args,**kwargs)

        return ret

    return inner

@log

def shoplist_add():

    print('增加一件物品')

@log

def shoplist_del():

    print('删除一件物品')

shoplist_add()

shoplist_del()

shoplist_del()

shoplist_del()

shoplist_del()

shoplist_del()

# 进阶作业(选做)：

# 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），就优先从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(*args,**kwargs):

        if os.path.getsize('web_cache'):

            with open('web_cache','rb') as f:

                return f.read()

        ret = func(*args,**kwargs)  #get()

        with open('web_cache','wb') as f:

            f.write(b'*********'+ret)

        return ret

    return inner

@cache

def get(url):

    code = urlopen(url).read()

    return code

# {'网址':"文件名"}

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

print(ret)

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

print(ret)

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

print(ret)

import os

from urllib.request import urlopen

def cache(func):

    def inner(*args,**kwargs):

        if os.path.getsize('web_cache'):

            with open('web_cache','r',encoding='utf-8') as f:

                return f.read()

        ret = func(*args,**kwargs)  #get()

        with open('web_cache','w',encoding='utf-8') as f:

            f.write(b'*********'+ret)

        return ret

    return inner

@cache

def get(url):

    code = urlopen(url).read()

    return code

# {'网址':"文件名"}

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

print(ret)

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

print(ret)

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

print(ret)