Contents
6.4. 装饰器¶
装饰器的作用，写一个可以反复使用的函数或者装饰器类，用于装饰其它函数
比如：账号密码多次需要登录的时候。
有些警告信息、提示信息多个地方需要显示的。
实现一个需求，不用到处修改代码，统一入口
以下就是一个简单的装饰器函数的定义代码：
def demo_decorater (fun): #定义装饰器函数（参数为fun，可所受函数对象）
def new_fun (*args,**kwargs): #新定义一个包装器函数用于返回
pass
fun(*args,**kwargs) #包装器函数中调用被装饰的函数
pass
return new_fun #返回包装器函数
此外，装饰器还可以嵌套装饰，比如以下代码中，函数decorated_fun()同时被abc和disp_run_time装饰器装饰，插入了两种不同类型的功能：
@abc
@disp_run_time
def decorated_fun():
pass
6.4.1. 1.装饰符¶
#!/usr/bin/env python
# -*- coding:utf8 -*-
# auther; 18793
# Date：2020/1/8 22:09
# filename: @装饰符.py
def checkParams(fn):
def wrapper(strname):
if isinstance(strname, (str)):
return fn(strname)
print("variable strname is not a string type")
return
return wrapper
@checkParamss
def wrapperfun(strname):
def recoder(age):
print("姓名：", strname, "年纪:", age)
return recoder
fa = wrapperfun("hujianli")
fa(22) # 姓名： hujianli 年纪: 22
fun = wrapperfun(22) #variable strname is not a string type
1.1 一个普通的装饰器函数¶
#!/usr/bin/env python
# -*- coding:utf8 -*-
# auther; 18793
# Date：2020/5/10 21:55
# filename: sample01.py
def abc(fun):
# 定义一个装饰器abc
def warpper(*args, **kwargs):
# 定义包装饰器函数
print("开始运行....")
# 调用被装饰的函数
fun(*args, **kwargs)
print("运行结束!")
return warpper
@abc
def demo_decoration(x): # 返回包装饰器函数
a = []
for i in range(x):
a.append(i)
print(a)
@abc
def hello(name):
print("Hello {}!".format(name))
if __name__ == '__main__':
demo_decoration(5)
print()
hello("hujianli")
"""
开始运行....
[0, 1, 2, 3, 4]
运行结束!
开始运行....
Hello hujianli!
运行结束!
"""
#!/usr/bin/env python
# -*- coding:utf8 -*-
# auther; 18793
# Date：2019/9/23 21:52
# filename: 装饰器函数001.py
import datetime
def time(func):
def wrapper():
start_time = datetime.datetime.now()
print(start_time)
func()
end_time = datetime.datetime.now()
print(end_time)
print("time use :{}".format(end_time - start_time))
return wrapper
@time
def loop():
print("start.....")
for i in range(100000000):
pass
print("finish......")
if __name__ == '__main__':
loop()
"""
2019-09-23 21:55:12.081090
start.....
finish......
2019-09-23 21:55:14.501618
time use :0:00:02.420528
"""
1.2 带参数的装饰器 1¶
#!/usr/bin/env python
#-*- coding:utf8 -*-
def pre_str(pre=''):
def decorator(old_function):
def new_function(a, b):
print("*"*30)
print(pre + ' input',"用户名:", a)
print(pre + ' input',"密码:", b)
print("*"*30)
return old_function(a, b)
return new_function
return decorator
#不带参数，默认值参数
@pre_str()
def sum_str(a,b):
return a,b
#装饰square_sum()，带参数^_^
@pre_str("^_^")
def square_sum(a, b):
return a,b
#装饰器square_diff(),带参数T_T
@pre_str("T_T")
def square_diff(a,b):
return a,b
if __name__ == '__main__':
print(sum_str("xiaojian722","admin#123"))
print(square_sum("hujianli", "123.com"))
print(square_diff("hujianli","1234.com"))
装饰器也是可以带参数的，比如“@abc（”callcall“）”。可以将实例9-6中的装饰器函数改写为带参数的装饰器，代码如下：
def abc(action):
def mabc(fun):
def wrapper (*args,**kwargs):
print ('开始运行...',action)
fun (*args,**kwargs)
print ('运行结束！', action)
return wrapper
return mabc
1.3 带参数的装饰器 2¶
#!/usr/bin/env python
# -*- coding:utf8 -*-
import time
def abc(action):
def mabc(func):
def wrapper(*args, **kwargs):
print("开始运行....", action)
func(*args, **kwargs)
print("运行结束！....", action)
return wrapper
return mabc
def timer(func):
def deco(*args, **kwargs):
start_time = time.time()
func(*args, **kwargs)
end_time = time.time()
print(end_time - start_time)
return deco
@timer
@abc("print_name") # 带参数的装饰器
def deam_print_name(name):
time.sleep(2)
print("Hello {}!".format(name))
@timer
@abc("list_info") # 带参数的装饰器
def deam_list_print(x):
a = []
time.sleep(2)
for i in range(x):
a.append(i)
print(a)
if __name__ == '__main__':
deam_list_print(8)
print(''.center(100, "#"))
print("".center(100, "#"))
deam_print_name("hujianli")
1.4 带参数的装饰器 3¶
#!/usr/bin/env python
#-*- coding:utf8 -*-
import time
def timer(parameter):
def out_wrapper(func):
def wrapper(*args,**kwargs):
if parameter == "task1":
start = time.time()
func(*args,**kwargs)
stop = time.time()
print("the task1 run time is :",stop - start)
elif parameter == "task2":
start = time.time()
func(*args,**kwargs)
stop = time.time()
print("the task2 run time is :",stop - start)
return wrapper
return out_wrapper
@timer("task1")
def task1():
time.sleep(2)
print("in the task1")
@timer("task2")
def task2():
time.sleep(3)
print("in the task2")
if __name__ == '__main__':
task1()
print("我是分割线".center(100, "*"))
task2()
6.4.2. 2.定义装饰类的装饰器¶
采用的方法是：定义内嵌类的函数，返回新类
代码示例
#!/usr/bin/env python
#-*- coding:utf8 -*-
#定义装饰类的装饰器，采用的方法是：定义内嵌类的函数，返回新类
#定义一个类装饰器及其使用的例子
def abc(myclss):
class InnerClass:
def __init__(self, z=0):
self.z = 0
self.wrapper = myclss() #实例化被装饰的类
def position(self):
self.wrapper.position()
print('z axis:',self.z)
return InnerClass #返回新定义的类
'''
定义一个能够装饰类的装饰器abc，定义了一个内嵌类InnerClass用于代替被装饰的类，并返回新的内嵌类，实例化普通类
之后，得到的就是被装饰器装饰后的类
'''
@abc
class coordination:
def __init__(self, x=0, y=0):
self.x = x
self.y = y
def position(self):
print("x axis:", self.x)
print("y axis:", self.y)
if __name__ == '__main__':
coor = coordination()
coor.position()
2.1类装饰器¶
#!/usr/bin/env python
#-*- coding:utf8 -*-
def decorator_class(SomeClass):
class NewClass(object):
def __init__(self,age):
self.total_display = 0
self.wrapped = SomeClass(age)
def display(self):
self.total_display +=1
print("*"*20)
print("total display", self.total_display)
print("*"*20)
self.wrapped.display()
return NewClass
@decorator_class
class Bird:
def __init__(self,age):
self.age = age
def display(self):
print("My age is ",self.age)
if __name__ == '__main__':
eagle_lord = Bird(5)
for i in range(3):
eagle_lord.display()
2.2类装饰器¶
#!/usr/bin/env python
# -*- coding:utf8 -*-
# auther; 18793
# Date：2019/9/23 21:57
# filename: 装饰类002.py
def addSex(myClass):
class InnerClass:
def __init__(self, name, age, sex):
self.sex = sex
self.wrapper = myClass(name, age)
def showInfo(self):
self.wrapper.showInfo()
print("sex:{}".format(self.sex))
return InnerClass
@addSex
class Person:
def __init__(self, name, age):
self.name = name
self.age = age
def showInfo(self):
print("name:{}".format(self.name))
print("age:{}".format(self.age))
if __name__ == '__main__':
p = Person("Tom", 18, "MALE")
p.showInfo()
"""
name:Tom
age:18
sex:MALE
"""
6.4.3. 3.利用装饰器实现失败重试¶
#!/usr/bin/env python
# -*- coding:utf8 -*-
# auther; 18793
# Date：2020/1/8 22:34
# filename: sample04.py
import subprocess
import requests
def Retry(second):
def decorator(func):
def warpper(*args, **kwargs):
att = 0 # 计数器
while att < second: # 按照计数器条件来循环
print(att)
try:
return func(*args, **kwargs) # 运行请求，或者命令
except Exception as e:
att += 1 # 计数器累加
return warpper
return decorator
@Retry(3)
def cmd_01(cmd):
subprocess.call(cmd)
# 简单的爬虫,重试3次爬取
@Retry(3)
def get_respone(url):
r = requests.get(url)
return r
cmd_01("dir1")
get_respone("http://www.baidu1.com")