设计模式十四（享元模式flyweight，python语言实现）
基本理论请参考相关书籍，这里直接给实例
基本解释：享元模式 ，flyweight, 通过对象单元共享技术实现轻量级。
公司信息CompanyInfo 分为 生成信息ProductionInfo和销售信息SalesInfo。
公司老板要求秘书Secretary(享元工厂，这里是信息享元工厂)，准备相应信息报表。
如果对应信息报表在秘书处没有存档，则秘书要生成新报表，并在秘书处存档。
如果对应信息报表存在，则秘书直接使用存档信息报表提交给老板。
如果老板感觉信息太旧，可以要求秘书生成当前信息的报表。
# -*- coding: utf-8 -*-######################################################## # Flyweight.py# Python implementation of the Class Client# Generated by Enterprise Architect# Created on: 12-十二月-2012 12:42:43# #######################################################from __future__ import divisionfrom __future__ import print_functionfrom __future__ import unicode_literalsfrom future_builtins import * import timeclass CompanyInfo(object): """This class declares an interface through which flyweights can receive and act on extrinsic state. """ def __init__(self, name="None"): self.name=name +"\n -- 建立时间:" + time.strftime('%Y-%m-%d %H:%M:%S', time.localtime()) pass def Info(self): print(self.name +"\n -- 使用时间:" + time.strftime('%Y-%m-%d %H:%M:%S', time.localtime()) ) passclass ProductionInfo(CompanyInfo): """This class declares an interface through which flyweights can receive and act on extrinsic state. """ def __init__(self, name="this is product's information"): super(ProductionInfo,self).__init__(name) passclass SalesInfo(CompanyInfo): """This class declares an interface through which flyweights can receive and act on extrinsic state. """ def __init__(self, name="this is sales' information"): super(SalesInfo,self).__init__(name) passclass Secretary(object): """This class (a) creates and manages flyweight objects, and (b) ensures that flyweights are shared properly. """ m_CompanyInfo= CompanyInfo() def __init__(self): self.dict=dict() pass def GetCurrentInfo(self,key): if self.dict.has_key(key): self.dict.pop(key) pass return self.GetInfo(key) pass def GetInfo(self, key): info=CompanyInfo() if self.dict.has_key(key): info=self.dict[key] pass else: if key=='P': info=ProductionInfo() pass elif key=='S': info=SalesInfo() pass else: info=None pass if info!=None: self.dict[key]=info pass pass return info pass#客户端class Client: """This class (a) maintains a reference to a flyweight, and (b) computes or stores the extrinsic state of flyweight(s). """ m_SalesInfo= SalesInfo() m_ProductionInfo= ProductionInfo() m_Secretary= Secretary() #老板要求秘书准备公司生产信息报表 info=m_Secretary.GetInfo('P') info.Info() time.sleep(2) #老板要求秘书准备公司销售信息报表 info=m_Secretary.GetInfo('S') info.Info() time.sleep(2) #老板要求秘书准备公司生产信息报表 #此时该报表已经在秘书处备案了，秘书直接取得备案信息 info=m_Secretary.GetInfo('P') info.Info() time.sleep(2) #因为备案的生产信息比较旧，老板要求秘书准备公司现在的生产信息报表 #此时，该报表需要重新生成 info=m_Secretary.GetCurrentInfo('P') info.Info()
运行结果：
