我们先来看一个例子:
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#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();
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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:
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# -*- 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()
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运行结果