装饰器

装饰器

装饰器就像我们穿长裤，在不影响内裤作用的前提下，给我们的身子提供了保暖的功效。装饰器的作用就是为已经存在的对象添加额外的功能。

作用：让其他函数在不需要做任何代码变动的前提下增加额外功能，装饰器的返回值也是一个函数对象。

最简单的装饰器

# 最简单的装饰器
# 为函数添加运行时间的功能
import time

def timer(funcname):
    def wrapper():
        start = time.time()
        funcname()
        stop = time.time()
        print("函数运行时间为%f" % (stop - start))
    return wrapper

@timer      # home = timer(home)
def home():
    time.sleep(1)
    print("welcome to index page")

home() # 未改变函数原先的调用方式

添加传入参数

import time
def timer(func):    # 函数运行时间装饰器
    def wrapper(*args, **kwargs):
        start1 = time.time()
        res = func(*args)
        stop1 = time.time()
        print("run time is %f" % (stop1 - start1))
        return res
    return wrapper


@timer        # foo = timmer(foo)
def foo():
    time.sleep(1)
    print("welcome to oldboy")

@timer
def home(name):    # home = timer(home)
    time.sleep(1)
    print("welcome to %s home" % name)

@timer          # home = timer(home)
def tell(name, age):
    time.sleep(1)
    print("my name is %s ,i am %s years old" % (name, age))
    
# 函数调用阶段
foo()
print("--------------")
home('zou')
print("--------------")
tell("chen", "18")

有参装饰器

# 有参装饰器
# 参数是选择认证方式
def auth2(auth_type="file"):  # 默认认证方式为文件判断
    def auth(func):
        def wrapper(*args, **kwargs):
            if auth_type == "file":
                count = 0
                while count < 3:         # 输入用户名和密码进行登陆
                    username = input("username:>>")    
                    password = input("password:>>")
                    if username == "zou" and password == "123":
                        print("登陆成功")
                        res = func(*args, **kwargs)   # 执行原函数
                        return res
                    else:
                        count += 1
                        if count == 3:
                            print("输错三次了，程序退出")
            elif auth_type == "sql":
                print("还没学sql认证")
        return wrapper
    return auth


@auth2()      # home = auth(home)
def home(name):
    print("its in %s's house" % name)

home("zou")   # 主函数入口

为函数添加认证装饰器，输错三次锁定用户
有三个txt文件，
blackname.txt-->存放黑名单

info.txt-->存放所有用户信息和密码
status.txt-->保存用户登陆状态，默认写入
status = {"user": None, "login": False}

# 有参装饰器为函数添加认证功能，
# 用户信息来源是文件或者数据库，三次验证失败锁定用户
def confirm2(auth_type = "file"):
    def confirm(func):
        def wrapper(*args, **kwargs):
            if auth_type == "file":          # 判断哪种方式认证
                with open("status.txt") as sfile:
                    data = sfile.readline().strip()
                    user_status = eval(data)           # 拿到用户登陆状态
                    if user_status["login"] == True:
                        func(*args, **kwargs)           # 用户已经登陆过
                    else:
                        username = input("username:>>")
                        with open("blackname.txt") as bfile:    # 判断是否在黑名单
                            for line in bfile:
                                if username in line.strip():
                                    print("用户被锁定")
                                    return 0
                        with open("info.txt") as ifile:         # 判断是否在用户数据库
                            status = {"user": None, "login": False}
                            for line in ifile:
                                _username, _password = line.strip().split()
                                if username == _username:
                                    count = 0
                                    while count < 3:
                                        password = input("passward:>>")  # 输入密码判断
                                        if password == _password:
                                            print("登陆成功")
                                            func(*args, **kwargs)        # 函数执行
                                            status["user"] = username
                                            status["login"] = True
                                            with open("status.txt", "w") as sfile:  # 写入登陆状态
                                                sfile.write(str(status))
                                            break
                                        else:
                                            count += 1
                                            continue
                                    if count == 3:
                                        with open("blackname.txt", "a") as bfile:
                                            bfile.write(username+"
")
                                        print("连续输错三次，用户被锁定")
            elif auth_type == "sql":
                print("还没学sql")
        return wrapper
    return confirm


@confirm2()
def home(name):
    print("welcome to %s home"% name)

@confirm2()
def index(name):
    print("欢迎来到%s主页程序" % name)

# 函数调用
home("zou")
index("zou")