Matlab状态模式(State)
状态模式就是将状态的条件判断语句转化成其函数重写形式,利用了面向对象语言的多态性,本文根据https://blog.****.net/lm324114/article/details/78819602的情景将状态模式用Matlab语言实现。
根据上图情景,用传统的方法实现如下:
RoomState.m
classdef RoomState < handle
enumeration
FREE
BOOKED
CHECKIN
end
end
IfRoom.m
classdef IfRoom < handle
properties
state;
end
methods
function obj = IfRoom()
obj.state = RoomState.FREE;
end
function bookRoom(obj)
switch obj.state
case RoomState.FREE
disp('完成预订...');
obj.state = RoomState.BOOKED;
case RoomState.BOOKED
disp('该房间已经被预订了...');
case RoomState.CHECKIN
disp('该房间已经有人入住了...');
end
end
function checkInRoom(obj)
switch obj.state
case RoomState.FREE
disp('空闲房间,入住..');
obj.state = RoomState.CHECKIN;
case RoomState.BOOKED
disp('入住房间....');
obj.state = RoomState.CHECKIN;
case RoomState.CHECKIN
disp('该房间已经有人入住了...');
end
end
function unsubscribeRoom(obj)
switch obj.state
case RoomState.FREE
disp('该房间尚未预订');
case RoomState.BOOKED
disp('已退订房间...');
obj.state = RoomState.FREE;
case RoomState.CHECKIN
disp('该房间已入住,不能退订');
end
end
function checkOutRoom(obj)
switch obj.state
case {RoomState.FREE, RoomState.BOOKED}
disp('该房间尚未入住');
case RoomState.CHECKIN
disp('已退房');
obj.state = RoomState.FREE;
end
end
end
end
测试代码:
ri = IfRoom();
ri.bookRoom();
ri.checkOutRoom();
ri.unsubscribeRoom();
ri.checkInRoom();
ri.checkOutRoom();
用状态模式实现如下:
State.m
classdef State < handle
properties
state;
end
methods(Abstract)
bookRoom(obj);
checkInRoom(obj)
unsubscribeRoom(obj)
checkOutRoom(obj)
end
end
FreeState.m
classdef FreeState < State
properties
room
end
methods
function obj = FreeState(room)
obj.room = room;
end
function bookRoom(obj)
disp('完成预订...');
obj.room.state = obj.room.BOOKED_STATE;
end
function checkInRoom(obj)
disp('空闲房间,入住..');
obj.room.state = obj.room.CHECKIN_STATE;
end
function unsubscribeRoom(~)
disp('该房间尚未预订');
end
function checkOutRoom(~)
disp('该房间尚未入住');
end
end
end
BookedState.m
classdef BookedState < State
properties
room
end
methods
function obj = BookedState(room)
obj.room = room;
end
function bookRoom(~)
disp('该房间已经被预订了...');
end
function checkInRoom(obj)
disp('入住房间....');
obj.room.state = obj.room.CHECKIN_STATE;
end
function unsubscribeRoom(obj)
disp('已退订房间...');
obj.room.state = obj.room.FREE_STATE;
end
function checkOutRoom(~)
disp('该房间尚未入住');
end
end
end
CheckInState.m
classdef CheckInState < State
properties
room
end
methods
function obj = CheckInState(room)
obj.room = room;
end
function bookRoom(~)
disp('该房间已经有人入住了...');
end
function checkInRoom(~)
disp('该房间已经有人入住了...');
end
function unsubscribeRoom(~)
disp('该房间已入住,不能退订');
end
function checkOutRoom(obj)
disp('已退房');
obj.room.state = obj.room.FREE_STATE;
end
end
end
Room.m
classdef Room < handle
properties
FREE_STATE;
BOOKED_STATE;
CHECKIN_STATE;
end
properties
state;
end
methods
function obj = Room()
obj.FREE_STATE = FreeState(obj);
obj.BOOKED_STATE = BookedState(obj);
obj.CHECKIN_STATE = CheckInState(obj);
obj.state = obj.FREE_STATE;
end
function bookRoom(obj)
obj.state.bookRoom();
end
function checkInRoom(obj)
obj.state.checkInRoom();
end
function unsubscribeRoom(obj)
obj.state.unsubscribeRoom();
end
function checkOutRoom(obj)
obj.state.checkOutRoom();
end
end
end
测试代码:
r = Room();
r.bookRoom();
r.checkOutRoom();
r.unsubscribeRoom();
r.checkInRoom();
r.checkOutRoom();
运行结果:
可以看出,两种方式的运行结果是一致的,但是状态模式比传统方法看上去更简洁。