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实例解析Python设计模式编程之桥接模式的运用

2016-03-02 11:50 936 查看

我们先来看一个例子：

#encoding=utf-8
#
#by panda
#桥接模式
def printInfo(info):
print unicode(info, 'utf-8').encode('gbk')
#抽象类：手机品牌
class HandsetBrand():
soft = None
def SetHandsetSoft(self, soft):
self.soft = soft
def Run(self):
pass
#具体抽象类：手机品牌1
class HandsetBrand1(HandsetBrand):
def Run(self):
printInfo('手机品牌1:')
self.soft.Run()
#具体抽象类：手机品牌2
class HandsetBrand2(HandsetBrand):
def Run(self):
printInfo('手机品牌2:')
self.soft.Run()
#功能类：手机软件
class HandsetSoft():
def Run(self):
pass
#具体功能类：游戏
class HandsetGame(HandsetSoft):
def Run(self):
printInfo('运行手机游戏')
#具体功能类：通讯录
class HandsetAddressList(HandsetSoft):
def Run(self):
printInfo('运行手机通信录')
def clientUI():
h1 = HandsetBrand1()
h1.SetHandsetSoft(HandsetAddressList())
h1.Run()
h1.SetHandsetSoft(HandsetGame())
h1.Run()
h2 = HandsetBrand2()
h2.SetHandsetSoft(HandsetAddressList())
h2.Run()
h2.SetHandsetSoft(HandsetGame())
h2.Run()
return
if __name__ == '__main__':
clientUI();

可以总结出类图是这样的：

所以，桥接模式的概念在于将系统抽象部分与它的实现部分分离，使它们可以独立地变化。
由于目标系统存在多个角度的分类，每一种分类都会有多种变化，那么就可以把多角度分离出来，让它们独立变化，减少它们之间的耦合。

下面我们再来看一个实例：

基本原理请参考相关书籍，这里直接给实例

假期旅游从目的地角度可以分为上海和大连，从方式角度可以分为跟团和独体

桥接模式把这两种分类连接起来可以进行选择。

类图：

# -*- coding: utf-8 -*-
#######################################################
#
# tour.py
# Python implementation of the Class DaLian
# Generated by Enterprise Architect
# Created on:   11-十二月-2012 16:53:52
#
#######################################################
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals
from future_builtins import *
class TravelForm(object):
"""This class defines the interface for implementation classes.
"""
def __init__(self, form="stay at home"):
self.form=form
pass
def GetForm(self):
return self.form
pass
pass
class Group(TravelForm):
"""This class implements the Implementor interface and defines its concrete
implementation.
"""
def __init__(self, form="by group"):
super(Group,self).__init__(form)
pass
pass
class Independent(TravelForm):
"""This class implements the Implementor interface and defines its concrete
implementation.
"""
def __init__(self, form="by myself"):
super(Independent,self).__init__(form)
pass
class Destination(object):
"""This class (a) defines the abstraction's interface, and (b) maintains a
reference to an object of type Implementor.
"""
m_TravelForm= TravelForm()
def __init__(self, info):
self.info=info
pass
def GetInfo(self):
# imp->Operation();
return print(self.info + " " +self.form.GetForm())
pass
def SetForm(self, form):
self.form=form
pass
class DaLian(Destination):
"""This class extends the interface defined by Abstraction.
"""
def __init__(self, info="Go to DaLian "):
super(DaLian,self).__init__(info)
pass
class ShangHai(Destination):
"""This class extends the interface defined by Abstraction.
"""
def __init__(self, info="Go to ShangHai"):
super(ShangHai,self).__init__(info)
pass
#客户端
if(__name__=="__main__"):
destination=ShangHai()
destination.SetForm(Group())
destination.GetInfo()
destination=DaLian()
destination.SetForm(Independent())
destination.GetInfo()

运行结果

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