设计模式（状态模式，python语言实现）
基本理论请参考相应书籍，这里直接给实例
基本说明：电梯（Context）内部维护着电梯的运行状态，如在几楼等信息。
state是电梯状态的的父类。子类有FloorA（一楼状态），FloorB（二楼状态）FloorC（三楼状态），FloorD（四楼状态）
客户端选择要去的楼层，电梯根据当前的状态决定是需要上行还是需要下行，并判断是否到目的地。
[python]
# -*- coding: utf-8 -*-
#######################################################
#
# state.py
# Python implementation of the Class Context
# Generated by Enterprise Architect
# Created on: 13-十二月-2012 14:23:46
#
#######################################################
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals
from future_builtins import *
class State(object):
"""This class defines an interface for encapsulating the behaviour associated with
a particular state of the Context.
"""
m_obj=None
def __init__(self, state=0):
self.state=state
self.current=None
self.up=None
self.down=None
pass
def Handle(self,state):
if self.state==state:
print('第%d' %self.state+'楼到了，请下电梯' )
State.m_obj=self www.2cto.com
pass
else:
self.SetContext()
if self.state<state:
print('正经过第%d' %self.state+'楼，电梯继续上行')
self.current=self.up
pass
else:
print('正经过第%d' %self.state+'楼，电梯继续下行')
self.current=self.down
pass
self.current.Handle(state)
pass
return State.m_obj
pass
def SetFloor(self, floor):
pass
def SetContext(self):
pass
class FloorA(State):
"""This class defines an interface for encapsulating the behaviour associated with
a particular state of the Context.
"""
def __init__(self, state=1):
super(FloorA,self).__init__(state)
pass
def SetContext(self):
self.up=FloorB()
self.down=None
pass
def SetFloor(self, floor):
pass
class FloorB(State):
"""This class defines an interface for encapsulating the behaviour associated with
a particular state of the Context.
"""
def __init__(self, state=2):
super(FloorB,self).__init__(state)
pass
def SetContext(self):
self.up=FloorC()
self.down=FloorA()
pass
def SetFloor(self, floor):
pass
class FloorC(State):
"""This class defines an interface for encapsulating the behaviour associated with
a particular state of the Context.
"""
def __init__(self, state=3):
super(FloorC,self).__init__(state)
pass
def SetContext(self):
self.up=FloorD()
self.down=FloorB()
pass
def SetFloor(self, floor):
pass
class FloorD(State):
"""This class defines an interface for encapsulating the behaviour associated with
a particular state of the Context.
"""
def __init__(self, state=4):
super(FloorD,self).__init__(state)
pass
def SetContext(self):
self.up=None
self.down=FloorC()
pass
def SetFloor(self, floor):
pass
class Context(object):
"""This class defines the interface of interest to clients and maintains an
instance of a ConcreteState subclass that defines the current state.
"""
m_State= State()
def __init__(self):
Context.m_State=FloorA()
pass
def SetState(self,state):
Context.m_State=state
pass
def Request(self,floor):
# state->Handle()
print('电梯在第%d楼'%Context.m_State.state)
current=Context.m_State.Handle(floor)
if current!=None:
self.SetState(current)
pass
else:
print('电梯运行出错')
pass
print('\n')
pass
pass
if(__name__=="__main__"):
#建立电梯
m_Context= Context()
#到四楼
m_Context.Request(4)
#然后有人到2楼
m_Context.Request(2)
#然后有人到3楼
m_Context.Request(3)
#然后有人到1楼
m_Context.Request(1)
运行结果：
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