‘每一个模式描述了一个在我们周围不断重复发生的问题’，以及该问题的解决方案的核心。这样你就能一次又一次地使用该方案而不必做重复劳动。
每一个设计模式系统地命名、解释和评价了面向对象系统中一个重复的和重复出现的设计。
设计模式四个基本要素：模式名称、问题、解决方案、效果。
设计模式六大原则：
1.开闭原则：一个软件实体如类、模块和函数应该对扩展开放，对修改关闭。即软件实体应尽量在不修改原有代码的情况下进行扩展。
2.里氏替换原则：所有引用基类的地方必须能透明地使用其子类地对象。
3.依赖倒置原则：高层模块不应该依赖底层模块，二者都应该依赖其抽象；抽象不应该依赖细节；细节依赖抽象。换言之，要针对接口编程，而不是针对实现编程。
4.使用多个专门的接口，而不使用单一的总接口，即客户端不应该依赖那些他不需要的接口。
5.迪米特法则：一个软件实体应当尽可能少地与其他实体发生相互作用。
6.单一职责原则：不要存在多于一个导致类变更的原因。通俗的说，即一个类只负责一项职责。
前戏介绍：
# coding : utf-8 # create by ztypl on 2017/5/24 from abc import abstractmethod, ABCMeta class Payment(metaclass=ABCMeta): @abstractmethod def pay(self, money): pass class Alipay(Payment): def pay(self, money): print("支付宝支付%s元" % money) class ApplePay(Payment): def pay(self, money): print("苹果支付%s元" % money) class WechatPay(Payment): def pay(self, money): print("微信支付%s元" % money) payment = Alipay() payment.pay(100)
设计模式分类：
创建型模式：
工厂方法模式
抽象工厂模式
创建者模式
单利模式
原型模式
结构形模式
适配器模式
组合模式
代理模式
桥接模式
装饰模式
外观模式
享元模式
普通工厂模式：
# coding : utf-8 # create by ztypl on 2017/5/24 from abc import abstractmethod, ABCMeta class Payment(metaclass=ABCMeta): @abstractmethod def pay(self, money): raise NotImplementedError class Alipay(Payment): def __init__(self, enable_yuebao=False): self.enable_yuebao = enable_yuebao def pay(self, money): if self.enable_yuebao: print("余额宝支付%s元" % money) else: print("支付宝支付%s元" % money) class ApplePay(Payment): def pay(self, money): print("苹果支付%s元" % money) class PaymentFactory: # 工厂类 封装了对象创建的细节 def create_payment(self, method): if method == "alipay": return Alipay() elif method == "applepay": return ApplePay() elif method == "yuebao": return Alipay(True) else: raise NameError(method) factory = PaymentFactory() payment = factory.create_payment("yuebao") payment.pay(100)
工厂方法模式：
# coding : utf-8 # create by ztypl on 2017/5/25 from abc import abstractmethod, ABCMeta class Payment(metaclass=ABCMeta): @abstractmethod def pay(self, money): raise NotImplementedError class Alipay(Payment): def pay(self, money): print("支付宝支付%s元" % money) class ApplePay(Payment): def pay(self, money): print("苹果支付%s元"%money) class PaymentFactory(metaclass=ABCMeta): @abstractmethod def create_payment(self): pass class AlipayFactory(PaymentFactory): def create_payment(self): return Alipay() class ApplePayFactory(PaymentFactory): def create_payment(self): return ApplePay() # 用户输入 # 支付宝，120 af = AlipayFactory() ali = af.create_payment() ali.pay(120)
抽象工厂模式：
# coding : utf-8 # create by ztypl on 2017/5/25 from abc import abstractmethod, ABCMeta # ------抽象产品------ class PhoneShell(metaclass=ABCMeta): @abstractmethod def show_shell(self): pass class CPU(metaclass=ABCMeta): @abstractmethod def show_cpu(self): pass class OS(metaclass=ABCMeta): @abstractmethod def show_os(self): pass # ------抽象工厂------ class PhoneFactory(metaclass=ABCMeta): @abstractmethod def make_shell(self): pass @abstractmethod def make_cpu(self): pass @abstractmethod def make_os(self): pass # ------具体产品------ class SmallShell(PhoneShell): def show_shell(self): print("普通手机小手机壳") class BigShell(PhoneShell): def show_shell(self): print("普通手机大手机壳") class AppleShell(PhoneShell): def show_shell(self): print("苹果手机壳") class SnapDragonCPU(CPU): def show_cpu(self): print("骁龙CPU") class MediaTekCPU(CPU): def show_cpu(self): print("联发科CPU") class AppleCPU(CPU): def show_cpu(self): print("苹果CPU") class Android(OS): def show_os(self): print("Android系统") class IOS(OS): def show_os(self): print("iOS系统") # ------具体工厂------ class MiFactory(PhoneFactory): def make_cpu(self): return SnapDragonCPU() def make_os(self): return Android() def make_shell(self): return BigShell() class HuaweiFactory(PhoneFactory): def make_cpu(self): return MediaTekCPU() def make_os(self): return Android() def make_shell(self): return SmallShell() class IPhoneFactory(PhoneFactory): def make_cpu(self): return AppleCPU() def make_os(self): return IOS() def make_shell(self): return AppleShell() # ------客户端------ class Phone: def __init__(self, cpu, os, shell): self.cpu = cpu self.os = os self.shell = shell def show_info(self): print("手机信息:") self.cpu.show_cpu() self.os.show_os() self.shell.show_shell() def make_phone(factory): cpu = factory.make_cpu() os = factory.make_os() shell = factory.make_shell() return Phone(cpu, os, shell) p1 = make_phone(IPhoneFactory()) p1.show_info()
创建者模式：
# coding : utf-8 # create by ztypl on 2017/5/25 import random from abc import abstractmethod, ABCMeta #------产品------ class Player: def __init__(self, face=None, body=None, arm=None, leg=None): self.face = face self.arm = arm self.leg = leg self.body = body def __str__(self): return "%s, %s, %s, %s" % (self.face, self.arm, self.body, self.leg) #------建造者------ class PlayerBuilder(metaclass=ABCMeta): @abstractmethod def build_face(self): pass @abstractmethod def build_arm(self): pass @abstractmethod def build_leg(self): pass @abstractmethod def build_body(self): pass @abstractmethod def get_player(self): pass class BeautifulWomanBuilder(PlayerBuilder): def __init__(self): self.player = Player() def build_face(self): self.player.face = "漂亮脸蛋" def build_arm(self): self.player.arm="细胳膊" def build_body(self): self.player.body="细腰" def build_leg(self): self.player.leg="长腿" def get_player(self): return self.player class RandomPlayerBuilder(PlayerBuilder): def __init__(self): self.player = Player() def build_face(self): self.player.face = random.choice(["瓜子脸","西瓜子脸"]) def build_arm(self): self.player.arm=random.choice(["长胳膊","短胳膊"]) def build_body(self): self.player.body=random.choice(["苗条","胖"]) def build_leg(self): self.player.leg=random.choice(["长腿","短腿"]) def get_player(self): return self.player class PlayerDirector: def __init__(self, builder): self.builder = builder # 控制组装顺序 def build_player(self): self.builder.build_body() self.builder.build_face() self.builder.build_arm() self.builder.build_leg() return self.builder.get_player() pd = PlayerDirector(RandomPlayerBuilder()) p = pd.build_player() print(p)
单利模式：
# coding : utf-8 # create by ztypl on 2017/5/25 from abc import abstractmethod, ABCMeta class Singleton(object): def __new__(cls, *args, **kwargs): if not hasattr(cls, "_instance"): cls._instance = super(Singleton, cls).__new__(cls) return cls._instance class MyClass(Singleton): def __init__(self, name=None): if name is not None: self.name = name a = MyClass("a") print(a) print(a.name) # b = MyClass("b") print(b) # print(b.name) # # print(a) # print(a.name)
组合模式：
# coding : utf-8 # create by ztypl on 2017/5/25 from abc import abstractmethod, ABCMeta class Graphic(metaclass=ABCMeta): @abstractmethod def draw(self): pass @abstractmethod def add(self, graphic): pass @abstractmethod def getchildren(self): pass class Point(Graphic): def __init__(self, x, y): self.x = x self.y = y def draw(self): print(self) def add(self, graphic): raise TypeError def getchildren(self): raise TypeError def __str__(self): return "点(%s, %s)" % (self.x, self.y) class Line(Graphic): def __init__(self, p1, p2): self.p1 = p1 self.p2 = p2 def draw(self): print(self) def add(self, graphic): raise TypeError def getchildren(self): raise TypeError def __str__(self): return "线段[%s, %s]" % (self.p1, self.p2) class Picture(Graphic): def __init__(self): self.children = [] def add(self, graphic): self.children.append(graphic) def getchildren(self): return self.children def draw(self): print("------复合图形------") for g in self.children: g.draw() print("------END------") pic1 = Picture() pic1.add(Point(2,3)) pic1.add(Line(Point(1,2), Point(4,5))) pic1.add(Line(Point(0,1), Point(2,1))) pic2 = Picture() pic2.add(Point(-2,-1)) pic2.add(Line(Point(0,0), Point(1,1))) pic = Picture() pic.add(pic1) pic.add(pic2) pic.draw()
适配器模式：
# coding : utf-8 # create by ztypl on 2017/5/25 from abc import abstractmethod, ABCMeta class Payment(metaclass=ABCMeta): @abstractmethod def pay(self, money): raise NotImplementedError class Alipay(Payment): def pay(self, money): print("支付宝支付%s元"%money) class ApplePay(Payment): def pay(self, money): print("苹果支付%s元"%money) #------待适配类------ class WechatPay: def huaqian(self, a, b): print("微信支付%s元"%(a+b)) #------类适配器------ class RealWeChatPay(Payment, WechatPay): def pay(self, money): return self.huaqian(money, 0) #------对象适配器------ class PayAdapter(Payment): def __init__(self, payment): self.payment = payment def pay(self, money): return self.payment.huaqian(money, 0) #RealWeChatPay().pay(100) PayAdapter(WechatPay()).pay(1000)
代理模式：
# coding : utf-8 # create by ztypl on 2017/5/26 from abc import ABCMeta, abstractmethod class Subject(metaclass=ABCMeta): @abstractmethod def get_content(self): pass class RealSubject(Subject): def __init__(self, filename): self.filename = filename print("读取%s文件内容"%filename) f = open(filename) self.content = f.read() f.close() def get_content(self): return self.content def set_content(self, content): f = open(self.filename, 'w') f.write(content) f.close() class ProxyA(Subject): def __init__(self, filename): self.subj = RealSubject(filename) def get_content(self): return self.subj.get_content() class ProxyB(Subject): def __init__(self, filename): self.filename = filename self.subj = None def get_content(self): if not self.subj: self.subj = RealSubject(self.filename) return self.subj.get_content() class ProxyC(Subject): def __init__(self, filename): self.subj = RealSubject(filename) def get_content(self): return self.get_content() def set_content(self): raise PermissionError # 写一个set_content b = ProxyB("abc.txt") #print(b.get_content())
责任链模式：
# coding : utf-8 # create by ztypl on 2017/5/27 from abc import ABCMeta, abstractmethod # # class Handler(metaclass=ABCMeta): # @abstractmethod # def handle_leave(self, day): # pass # # # class GeneralManagerHandler(Handler): # def handle_leave(self, day): # if day < 10: # print("总经理批准%d天假"%day) # else: # print("呵呵") # # # class DepartmentManagerHandler(Handler): # def __init__(self): # self.successor = GeneralManagerHandler() # def handle_leave(self, day): # if day < 7: # print("部门经理批准%d天假"%day) # else: # print("部门经理无权准假") # self.successor.handle_leave(day) # # # class ProjectDirectorHandler(Handler): # def __init__(self): # self.successor = DepartmentManagerHandler() # def handle_leave(self, day): # if day < 3: # print("项目主管批准%d天假") # else: # print("项目主管无权准假") # self.successor.handle_leave(day) # # # day = 4 # h = ProjectDirectorHandler() # h.handle_leave(day) # #--高级例子--模仿js事件处理 class Handler(metaclass=ABCMeta): @abstractmethod def add_event(self, func): pass @abstractmethod def handle(self): pass class BodyHandler(Handler): def __init__(self): self.func = None def add_event(self, func): self.func = func def handle(self): if self.func: return self.func() else: print("已到最后一级，无法处理") class ElementHandler(Handler): def __init__(self, successor): self.func = None self.successor = successor def add_event(self, func): self.func = func def handle(self): if self.func: return self.func() else: return self.successor.handle() # 客户端 # <body><div><a> body = {'type': 'body', 'name': 'body', 'children': [], 'father': None} div = {'type': 'div', 'name': 'div', 'children': [], 'father': body} a = {'type': 'a', 'name': 'a', 'children': [], 'father': div} body['children'].append(div) div['children'].append(a) body['event_handler'] = BodyHandler() div['event_handler'] = ElementHandler(div['father']['event_handler']) a['event_handler'] = ElementHandler(a['father']['event_handler']) def attach_event(element, func): element['event_handler'].add_event(func) #test def func_div(): print("这是给div的函数") def func_a(): print("这是给a的函数") def func_body(): print("这是给body的函数") #attach_event(div, func_div) #attach_event(a, func_a) #attach_event(body, func_body) a['event_handler'].handle()
迭代器模式：
# coding : utf-8 # create by ztypl on 2017/5/27 class LinkList: """链表 头结点保存链表的长度""" class Node: def __init__(self, item=None): self.item = item self.next = None class LinkListIterator: def __init__(self, node): self.node = node def __next__(self): if self.node: cur_node = self.node self.node = cur_node.next return cur_node.item else: raise StopIteration def __iter__(self): return self def __init__(self, iterable=None): self.head = LinkList.Node(0) self.tail = self.head self.extend(iterable) def append(self, obj): s = LinkList.Node(obj) self.tail.next = s self.tail = s def extend(self, iterable): for obj in iterable: self.append(obj) self.head.item += len(iterable) def __iter__(self): return self.LinkListIterator(self.head.next) def __len__(self): return self.head.item def __str__(self): return "<<"+", ".join(map(str, self))+">>" li = [i for i in range(100)] print(li) lk = LinkList(li) # for i in lk: # print(i) print(lk) # print(len(lk))
观察者模式
# coding : utf-8 # create by ztypl on 2017/5/27 from abc import ABCMeta, abstractmethod class Observer(metaclass=ABCMeta): @abstractmethod def update(self, notice): pass class Notice: def __init__(self): self.observers = [] # 记录该主体的观察者（订阅者） def attach(self, obs): self.observers.append(obs) def detach(self, obs): obs.company_info = None self.observers.remove(obs) def notify(self): for obj in self.observers: obj.update(self) class ManagerNotice(Notice): def __init__(self, company_info=None): super().__init__() self.__company_info = company_info @property def company_info(self): return self.__company_info @company_info.setter def company_info(self, info): self.__company_info = info self.notify() class Manager(Observer): def __init__(self): self.company_info = None def update(self, noti): self.company_info = noti.company_info notice = ManagerNotice() alex = Manager() wusir = Manager() # print(alex.company_info) # print(wusir.company_info) notice.attach(alex) notice.attach(wusir) # notice.company_info="公司运行良好" # print(alex.company_info) print(wusir.company_info) # notice.detach(wusir) # notice.company_info="公司要破产了" print(alex.company_info) print(wusir.company_info)
策略模式：
# coding : utf-8 # create by ztypl on 2017/5/27 from abc import ABCMeta, abstractmethod import random class Sort(metaclass=ABCMeta): @abstractmethod def sort(self, data): pass class QuickSort(Sort): def quick_sort(self, data, left, right): if left < right: mid = self.partition(data, left, right) self.quick_sort(data, left, mid - 1) self.quick_sort(data, mid + 1, right) def partition(self, data, left, right): tmp = data[left] while left < right: while left < right and data[right] >= tmp: right -= 1 data[left] = data[right] while left < right and data[left] <= tmp: left += 1 data[right] = data[left] data[left] = tmp return left def sort(self, data): print("快速排序") return self.quick_sort(data, 0, len(data) - 1) class MergeSort(Sort): def merge(self, data, low, mid, high): i = low j = mid + 1 ltmp = [] while i <= mid and j <= high: if data[i] <= data[j]: ltmp.append(data[i]) i += 1 else: ltmp.append(data[j]) j += 1 while i <= mid: ltmp.append(data[i]) i += 1 while j <= high: ltmp.append(data[j]) j += 1 data[low:high + 1] = ltmp def merge_sort(self, data, low, high): if low < high: mid = (low + high) // 2 self.merge_sort(data, low, mid) self.merge_sort(data, mid + 1, high) self.merge(data, low, mid, high) def sort(self, data): print("归并排序") return self.merge_sort(data, 0, len(data) - 1) class Context: def __init__(self, data, strategy=None): self.data = data self.strategy = strategy def set_strategy(self, strategy): self.strategy = strategy def do_strategy(self): if self.strategy: self.strategy.sort(self.data) else: raise TypeError li = list(range(100000)) random.shuffle(li) context = Context(li, MergeSort()) context.do_strategy() #print(context.data) random.shuffle(context.data) context.set_strategy(QuickSort()) context.do_strategy()
模板方法模式
# coding : utf-8 # create by ztypl on 2017/5/27 from abc import ABCMeta, abstractmethod class IOHandler(metaclass=ABCMeta): @abstractmethod def open(self, name): pass @abstractmethod def deal(self, change): pass @abstractmethod def close(self): pass def process(self, name, change): self.open(name) self.deal(change) self.close() class FileHandler(IOHandler):