基于Python学习《Head First设计模式》第六章 命令模式

遥控器项目

实现思路

实现类图

再次梳理

代码实现

class RemoteControl:"""遥控器"""on_commands: List[Command]off_commands: List[Command]def __init__(self):self.on_commands = []self.off_commands = []no_command = NoCommand()for _ in range(7):self.on_commands.append(no_command)self.off_commands.append(no_command)def set_command(self, slot: int, on_command: Command, off_command: Command):self.on_commands[slot] = on_commandself.off_commands[slot] = off_commanddef on_button_was_pushed(self, slot: int):self.on_commands[slot].excute()def off_button_was_pushed(self, slot: int):self.off_commands[slot].excute()def __str__(self):buffer_str = []for i in range(len(self.on_commands)):buffer_str.append(f'[卡槽{i + 1}]{self.on_commands[i].__class__.__qualname__}\t{self.off_commands[i].__class__.__qualname__}')return "\n".join(buffer_str)

class LightOffCommand(Command):light: Lightdef __init__(self, light: Light):self.light = lightdef excute(self):self.light.off()def undo(self):passclass StereoOnWithCDCommand(Command):stereo: Stereodef __init__(self, stereo: Stereo):self.stereo = stereodef excute(self):self.stereo.on()self.stereo.set_cd()self.stereo.set_volume(11)def undo(self):pass

if __name__ == '__main__':remote_control = RemoteControl()living_room_light = Light("Living Room light")kitchen_light = Light("Kitchen light")stereo = Stereo("Living Room Stereo")living_room_light_on = LightOnCommand(living_room_light)living_room_light_off = LightOffCommand(living_room_light)kitchen_light_on = LightOnCommand(kitchen_light)kitchen_light_off = LightOffCommand(kitchen_light)stereo_on = StereoOnWithCDCommand(stereo)stereo_off = StereoOffWithCDCommand(stereo)remote_control.set_command(0, living_room_light_on, living_room_light_off)remote_control.set_command(1, kitchen_light_on, kitchen_light_off)remote_control.set_command(2, stereo_on, stereo_off)print(remote_control)print()remote_control.on_button_was_pushed(0)remote_control.off_button_was_pushed(0)remote_control.on_button_was_pushed(1)remote_control.off_button_was_pushed(1)remote_control.on_button_was_pushed(2)remote_control.off_button_was_pushed(2)

设计全貌

完整代码

与书上的代码略有不同，整体结构是一样的。书上是吊扇，我这里是音响。

from abc import ABCMeta, abstractmethod, ABC
from typing import Listclass Command(ABC):@abstractmethoddef excute(self):pass@abstractmethoddef undo(self):passclass NoCommand(Command):def excute(self):passdef undo(self):passclass Light:"""电灯"""name: strdef __init__(self, name):self.name = namedef off(self):print(f'{self.name} is off.')def on(self):print(f'{self.name} is on.')class LightOnCommand(Command):light: Lightdef __init__(self, light: Light):self.light = lightdef excute(self):self.light.on()def undo(self):print('撤销操作，', end='')self.light.off()class LightOffCommand(Command):light: Lightdef __init__(self, light: Light):self.light = lightdef excute(self):self.light.off()def undo(self):print('撤销操作，', end='')self.light.on()class Stereo:"""音响"""name: strdef __init__(self, name):self.name = namedef off(self):print(f'{self.name} is off.')def on(self):print(f'{self.name} is on.')def set_cd(self):print(f'{self.name} is set for CD input.')def set_volume(self, volume: int):print(f'{self.name} volume set to {volume}.')class StereoOnWithCDCommand(Command):stereo: Stereodef __init__(self, stereo: Stereo):self.stereo = stereodef excute(self):self.stereo.on()self.stereo.set_cd()self.stereo.set_volume(11)def undo(self):print('撤销操作，', end='')self.stereo.off()class StereoOffWithCDCommand(Command):stereo: Stereodef __init__(self, stereo: Stereo):self.stereo = stereodef excute(self):self.stereo.off()def undo(self):print('撤销操作，', end='')self.stereo.on()class RemoteControl:"""遥控器"""on_commands: List[Command]off_commands: List[Command]undo_command: Commanddef __init__(self):self.on_commands = []self.off_commands = []no_command = NoCommand()for _ in range(7):self.on_commands.append(no_command)self.off_commands.append(no_command)self.undo_command = no_commanddef set_command(self, slot: int, on_command: Command, off_command: Command):self.on_commands[slot] = on_commandself.off_commands[slot] = off_commanddef on_button_was_pushed(self, slot: int):self.on_commands[slot].excute()self.undo_command = self.on_commands[slot]def off_button_was_pushed(self, slot: int):self.off_commands[slot].excute()self.undo_command = self.off_commands[slot]def undo_button_was_pushed(self):self.undo_command.undo()def __str__(self):buffer_str = []for i in range(len(self.on_commands)):buffer_str.append(f'[卡槽{i + 1}]{self.on_commands[i].__class__.__qualname__}\t{self.off_commands[i].__class__.__qualname__}')return "\n".join(buffer_str)if __name__ == '__main__':remote_control = RemoteControl()living_room_light = Light("Living Room light")kitchen_light = Light("Kitchen light")stereo = Stereo("Living Room Stereo")living_room_light_on = LightOnCommand(living_room_light)living_room_light_off = LightOffCommand(living_room_light)kitchen_light_on = LightOnCommand(kitchen_light)kitchen_light_off = LightOffCommand(kitchen_light)stereo_on = StereoOnWithCDCommand(stereo)stereo_off = StereoOffWithCDCommand(stereo)remote_control.set_command(0, living_room_light_on, living_room_light_off)remote_control.set_command(1, kitchen_light_on, kitchen_light_off)remote_control.set_command(2, stereo_on, stereo_off)print(remote_control)print()remote_control.on_button_was_pushed(0)remote_control.off_button_was_pushed(0)remote_control.undo_button_was_pushed()remote_control.on_button_was_pushed(1)remote_control.undo_button_was_pushed()remote_control.off_button_was_pushed(1)remote_control.off_button_was_pushed(2)remote_control.on_button_was_pushed(2)remote_control.undo_button_was_pushed()"""运行结果：
[卡槽1]LightOnCommand	LightOffCommand
[卡槽2]LightOnCommand	LightOffCommand
[卡槽3]StereoOnWithCDCommand	StereoOffWithCDCommand
[卡槽4]NoCommand	NoCommand
[卡槽5]NoCommand	NoCommand
[卡槽6]NoCommand	NoCommand
[卡槽7]NoCommand	NoCommandLiving Room light is on.
Living Room light is off.
撤销操作，Living Room light is on.
Kitchen light is on.
撤销操作，Kitchen light is off.
Kitchen light is off.
Living Room Stereo is off.
Living Room Stereo is on.
Living Room Stereo is set for CD input.
Living Room Stereo volume set to 11.
撤销操作，Living Room Stereo is off.
"""

添加撤销操作

from abc import ABCMeta, abstractmethod, ABC
from typing import Listclass Command(ABC):@abstractmethoddef excute(self):pass@abstractmethoddef undo(self):passclass NoCommand(Command):def excute(self):passdef undo(self):passclass Stereo:"""音响"""name: strHIGH = 90MEDIUM = 40LOW = 10OFF = 0_volume: intdef __init__(self, name):self.name = nameself._volume = Stereo.OFFdef off(self):print(f'{self.name} is off.')def on(self):print(f'{self.name} is on.')def set_cd(self):print(f'{self.name} is set for CD input.')def set_volume(self, volume: int):self._volume = volumeprint(f'{self.name} volume set to {volume}.')def get_volume(self):return self._volumedef volume_high(self):print(f'音量设置为{Stereo.HIGH}')self._volume = Stereo.HIGHdef volume_medium(self):print(f'音量设置为{Stereo.MEDIUM}')self._volume = Stereo.MEDIUMdef volume_low(self):print(f'音量设置为{Stereo.LOW}')self._volume = Stereo.LOWclass StereoOnWithCDCommand(Command):stereo: Stereopre_volume: intdef __init__(self, stereo: Stereo):self.stereo = stereodef excute(self):self.pre_volume = self.stereo.get_volume()self.stereo.on()self.stereo.set_cd()self.stereo.set_volume(Stereo.MEDIUM)def undo(self):print('撤销操作，', end='')class StereoHighVolumeWithCDCommand(Command):pre_volume: intdef __init__(self, stereo: Stereo):self.stereo = stereodef excute(self):self.pre_volume = self.stereo.get_volume()self.stereo.volume_high()def undo(self):print('撤销操作，', end='')if self.pre_volume == Stereo.HIGH:self.stereo.volume_high()elif self.pre_volume == Stereo.MEDIUM:self.stereo.volume_medium()elif self.pre_volume == Stereo.LOW:self.stereo.volume_low()else:self.stereo.off()class StereoLowVolumeWithCDCommand(Command):pre_volume: intdef __init__(self, stereo: Stereo):self.stereo = stereodef excute(self):self.pre_volume = self.stereo.get_volume()self.stereo.volume_low()def undo(self):print('撤销操作，', end='')if self.pre_volume == Stereo.HIGH:self.stereo.volume_high()elif self.pre_volume == Stereo.MEDIUM:self.stereo.volume_medium()elif self.pre_volume == Stereo.LOW:self.stereo.volume_low()else:self.stereo.off()class StereoOffWithCDCommand(Command):stereo: Stereodef __init__(self, stereo: Stereo):self.stereo = stereodef excute(self):self.stereo.off()def undo(self):print('撤销操作，', end='')self.stereo.on()class RemoteControlWithUndo:"""遥控器"""on_commands: List[Command]off_commands: List[Command]undo_command: Commanddef __init__(self):self.on_commands = []self.off_commands = []no_command = NoCommand()for _ in range(7):self.on_commands.append(no_command)self.off_commands.append(no_command)self.undo_command = no_commanddef set_command(self, slot: int, on_command: Command, off_command: Command):self.on_commands[slot] = on_commandself.off_commands[slot] = off_commanddef on_button_was_pushed(self, slot: int):self.on_commands[slot].excute()self.undo_command = self.on_commands[slot]def off_button_was_pushed(self, slot: int):self.off_commands[slot].excute()self.undo_command = self.off_commands[slot]def undo_button_was_pushed(self):self.undo_command.undo()def __str__(self):buffer_str = []for i in range(len(self.on_commands)):buffer_str.append(f'[卡槽{i + 1}]{self.on_commands[i].__class__.__qualname__}\t{self.off_commands[i].__class__.__qualname__}')return "\n".join(buffer_str)if __name__ == '__main__':remote_control = RemoteControlWithUndo()stereo = Stereo('音响')stereo_off = StereoOffWithCDCommand(stereo)stereo_high_volume = StereoHighVolumeWithCDCommand(stereo)stereo_low_volume = StereoLowVolumeWithCDCommand(stereo)remote_control.set_command(0, stereo_high_volume, stereo_off)remote_control.set_command(1, stereo_low_volume, stereo_off)print(remote_control)remote_control.on_button_was_pushed(0)remote_control.off_button_was_pushed(0)remote_control.undo_button_was_pushed()remote_control.on_button_was_pushed(1)remote_control.undo_button_was_pushed()"""运行结果：
[卡槽1]StereoHighVolumeWithCDCommand	StereoOffWithCDCommand
[卡槽2]StereoLowVolumeWithCDCommand	StereoOffWithCDCommand
[卡槽3]NoCommand	NoCommand
[卡槽4]NoCommand	NoCommand
[卡槽5]NoCommand	NoCommand
[卡槽6]NoCommand	NoCommand
[卡槽7]NoCommand	NoCommand
音量设置为90
音响 is off.
撤销操作，音响 is on.
音量设置为10
撤销操作，音量设置为90
"""

批量操作

使用宏命令

from abc import ABCMeta, abstractmethod, ABC
from typing import Listclass Command(ABC):@abstractmethoddef excute(self):pass@abstractmethoddef undo(self):passclass NoCommand(Command):def excute(self):passdef undo(self):passclass MacroCommand(Command):commands: List[Command]def __init__(self, commands: List[Command]):self.commands = commandsdef excute(self):for command in self.commands:command.excute()def undo(self):for command in self.commands:command.undo()class Light:"""电灯"""name: strdef __init__(self, name):self.name = namedef off(self):print(f'{self.name} is off.')def on(self):print(f'{self.name} is on.')class LightOnCommand(Command):light: Lightdef __init__(self, light: Light):self.light = lightdef excute(self):self.light.on()def undo(self):print('撤销操作，', end='')self.light.off()class LightOffCommand(Command):light: Lightdef __init__(self, light: Light):self.light = lightdef excute(self):self.light.off()def undo(self):print('撤销操作，', end='')self.light.on()class Stereo:"""音响"""name: strdef __init__(self, name):self.name = namedef off(self):print(f'{self.name} is off.')def on(self):print(f'{self.name} is on.')def set_cd(self):print(f'{self.name} is set for CD input.')def set_volume(self, volume: int):print(f'{self.name} volume set to {volume}.')class StereoOnWithCDCommand(Command):stereo: Stereodef __init__(self, stereo: Stereo):self.stereo = stereodef excute(self):self.stereo.on()self.stereo.set_cd()self.stereo.set_volume(11)def undo(self):print('撤销操作，', end='')self.stereo.off()class StereoOffWithCDCommand(Command):stereo: Stereodef __init__(self, stereo: Stereo):self.stereo = stereodef excute(self):self.stereo.off()def undo(self):print('撤销操作，', end='')self.stereo.on()class RemoteControl:"""遥控器"""on_commands: List[Command]off_commands: List[Command]undo_command: Commanddef __init__(self):self.on_commands = []self.off_commands = []no_command = NoCommand()for _ in range(7):self.on_commands.append(no_command)self.off_commands.append(no_command)self.undo_command = no_commanddef set_command(self, slot: int, on_command: Command, off_command: Command):self.on_commands[slot] = on_commandself.off_commands[slot] = off_commanddef on_button_was_pushed(self, slot: int):self.on_commands[slot].excute()self.undo_command = self.on_commands[slot]def off_button_was_pushed(self, slot: int):self.off_commands[slot].excute()self.undo_command = self.off_commands[slot]def undo_button_was_pushed(self):self.undo_command.undo()def __str__(self):buffer_str = []for i in range(len(self.on_commands)):buffer_str.append(f'[卡槽{i + 1}]{self.on_commands[i].__class__.__qualname__}\t{self.off_commands[i].__class__.__qualname__}')return "\n".join(buffer_str)if __name__ == '__main__':remote_control = RemoteControl()living_room_light = Light("Living Room light")kitchen_light = Light("Kitchen light")stereo = Stereo("Living Room Stereo")living_room_light_on = LightOnCommand(living_room_light)living_room_light_off = LightOffCommand(living_room_light)kitchen_light_on = LightOnCommand(kitchen_light)kitchen_light_off = LightOffCommand(kitchen_light)stereo_on = StereoOnWithCDCommand(stereo)stereo_off = StereoOffWithCDCommand(stereo)remote_control.set_command(0, living_room_light_on, living_room_light_off)remote_control.set_command(1, kitchen_light_on, kitchen_light_off)remote_control.set_command(2, stereo_on, stereo_off)party_on_macro = [living_room_light_on, kitchen_light_on, stereo_on]party_on = MacroCommand(party_on_macro)party_off = MacroCommand([living_room_light_off, kitchen_light_off, stereo_off])remote_control.set_command(3, party_on, party_off)print(remote_control)print()print('---Pushing Macro On---')remote_control.on_button_was_pushed(3)print()print('---Pushing Macro Off---')remote_control.off_button_was_pushed(3)print()print('---Pushing Macro Undo---')remote_control.undo_button_was_pushed()"""运行结果：
[卡槽1]LightOnCommand	LightOffCommand
[卡槽2]LightOnCommand	LightOffCommand
[卡槽3]StereoOnWithCDCommand	StereoOffWithCDCommand
[卡槽4]MacroCommand	MacroCommand
[卡槽5]NoCommand	NoCommand
[卡槽6]NoCommand	NoCommand
[卡槽7]NoCommand	NoCommand---Pushing Macro On---
Living Room light is on.
Kitchen light is on.
Living Room Stereo is on.
Living Room Stereo is set for CD input.
Living Room Stereo volume set to 11.---Pushing Macro Off---
Living Room light is off.
Kitchen light is off.
Living Room Stereo is off.---Pushing Macro Undo---
撤销操作，Living Room light is on.
撤销操作，Kitchen light is on.
撤销操作，Living Room Stereo is on.
"""

命令模式的用途

请求队列、日志请求

总结