一、观察者模式介绍

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二、观察者模式UML

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三、python实现观察者模式（demo1、2）

1、demo1

"""
"""
观察者模式
"""

class Subject(object):
def init(self):
self.__observers = []

def register(self, observer):
    self.__observers.append(observer)

def notifyAll(self, *args, **kwargs):
    for observer in self.__observers:
        observer.notify(self, *args, **kwargs)

class Observer1(object):
def init(self, subject):
subject.register(self)

def notify(self, subject, *args):
    print(type(self).__name__, ":: Got", args, "From", subject)

class Observer2(object):
def init(self, subject):
subject.register(self)

def notify(self, subject, *args):
    print(type(self).__name__, ":: Got", args, "From", subject)

if name == "main":
subject = Subject()
observer1 = Observer1(subject)
observer2 = Observer2(subject)

subject.notifyAll('notification')

"""

2、demo2

"""
"""
观察者模式:新闻内容订阅和通知
"""
from abc import ABCMeta, abstractmethod

subject

class NewsPublisher(object):
def init(self):
self.__subscribers = []
self.__latestNews = None

def attach(self, subscriber):
    self.__subscribers.append(subscriber)

def detach(self):
    return self.__subscribers.pop()

def get_subscribers(self):
    return [type(x).__name__ for x in self.__subscribers]

def notifySubscribers(self):
    for sub in self.__subscribers:
        sub.update()

def addNews(self, news):
    self.__latestNews = news

def getNews(self):
    return "Got News: ", self.__latestNews

observer

class Subscriber(metaclass=ABCMeta):
@abstractmethod
def update(self):
pass

class SMSSubscriber(Subscriber):
def init(self, publisher):
self.publisher = publisher
self.publisher.attach(self)

def update(self):
    print(type(self).__name__, self.publisher.getNews())

class EmailSubscriber(Subscriber):
def init(self, publisher):
self.publisher = publisher
self.publisher.attach(self)

def update(self):
    print(type(self).__name__, self.publisher.getNews())

class OtherSubscriber(Subscriber):
def init(self, publisher):
self.publisher = publisher
self.publisher.attach(self)

def update(self):
    print(type(self).__name__, self.publisher.getNews())

client

if name == "main":
news_publisher = NewsPublisher()
for subscriber in [SMSSubscriber, EmailSubscriber, OtherSubscriber]:
subscriber(news_publisher)
print("\n Subscribers: ", news_publisher.get_subscribers())

news_publisher.addNews("Hello world! ")
news_publisher.notifySubscribers()

print("\n Detached: ", type(news_publisher.detach()).__name__)
print("\n Subscribers: ", news_publisher.get_subscribers())

news_publisher.addNews("Second News! ")
news_publisher.notifySubscribers()

"""