基于Python学习《Head First设计模式》第六章 命令模式

哆啦A梦的口袋呀2025-06-08 13:15

遥控器项目


实现思路



实现类图


再次梳理

代码实现

python 复制代码 
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_command
        self.off_commands[slot] = off_command

    def 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)
python 复制代码 
class LightOffCommand(Command):
    light: Light

    def __init__(self, light: Light):
        self.light = light

    def excute(self):
        self.light.off()

    def undo(self):
        pass
       

class StereoOnWithCDCommand(Command):
    stereo: Stereo

    def __init__(self, stereo: Stereo):
        self.stereo = stereo

    def excute(self):
        self.stereo.on()
        self.stereo.set_cd()
        self.stereo.set_volume(11)

    def undo(self):
        pass
python 复制代码 
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。

python 复制代码 
from abc import ABCMeta, abstractmethod, ABC
from typing import List


class Command(ABC):

    @abstractmethod
    def excute(self):
        pass

    @abstractmethod
    def undo(self):
        pass


class NoCommand(Command):

    def excute(self):
        pass

    def undo(self):
        pass


class Light:
    """电灯"""
    name: str

    def __init__(self, name):
        self.name = name

    def off(self):
        print(f'{self.name} is off.')

    def on(self):
        print(f'{self.name} is on.')


class LightOnCommand(Command):
    light: Light

    def __init__(self, light: Light):
        self.light = light

    def excute(self):
        self.light.on()

    def undo(self):
        print('撤销操作，', end='')
        self.light.off()


class LightOffCommand(Command):
    light: Light

    def __init__(self, light: Light):
        self.light = light

    def excute(self):
        self.light.off()

    def undo(self):
        print('撤销操作，', end='')
        self.light.on()


class Stereo:
    """音响"""
    name: str

    def __init__(self, name):
        self.name = name

    def 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: Stereo

    def __init__(self, stereo: Stereo):
        self.stereo = stereo

    def 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: Stereo

    def __init__(self, stereo: Stereo):
        self.stereo = stereo

    def 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: 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)
        self.undo_command = no_command

    def set_command(self, slot: int, on_command: Command, off_command: Command):
        self.on_commands[slot] = on_command
        self.off_commands[slot] = off_command

    def 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	NoCommand

Living 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

python 复制代码 
from abc import ABCMeta, abstractmethod, ABC
from typing import List


class Command(ABC):

    @abstractmethod
    def excute(self):
        pass

    @abstractmethod
    def undo(self):
        pass


class NoCommand(Command):

    def excute(self):
        pass

    def undo(self):
        pass


class Stereo:
    """音响"""
    name: str
    HIGH = 90
    MEDIUM = 40
    LOW = 10
    OFF = 0
    _volume: int

    def __init__(self, name):
        self.name = name
        self._volume = Stereo.OFF

    def 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 = volume
        print(f'{self.name} volume set to {volume}.')

    def get_volume(self):
        return self._volume

    def volume_high(self):
        print(f'音量设置为{Stereo.HIGH}')
        self._volume = Stereo.HIGH

    def volume_medium(self):
        print(f'音量设置为{Stereo.MEDIUM}')
        self._volume = Stereo.MEDIUM

    def volume_low(self):
        print(f'音量设置为{Stereo.LOW}')
        self._volume = Stereo.LOW


class StereoOnWithCDCommand(Command):
    stereo: Stereo
    pre_volume: int

    def __init__(self, stereo: Stereo):
        self.stereo = stereo

    def 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: int

    def __init__(self, stereo: Stereo):
        self.stereo = stereo

    def 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: int

    def __init__(self, stereo: Stereo):
        self.stereo = stereo

    def 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: Stereo

    def __init__(self, stereo: Stereo):
        self.stereo = stereo

    def 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: 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)
        self.undo_command = no_command

    def set_command(self, slot: int, on_command: Command, off_command: Command):
        self.on_commands[slot] = on_command
        self.off_commands[slot] = off_command

    def 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

python 复制代码 
from abc import ABCMeta, abstractmethod, ABC
from typing import List


class Command(ABC):

    @abstractmethod
    def excute(self):
        pass

    @abstractmethod
    def undo(self):
        pass


class NoCommand(Command):

    def excute(self):
        pass

    def undo(self):
        pass


class MacroCommand(Command):
    commands: List[Command]

    def __init__(self, commands: List[Command]):
        self.commands = commands

    def excute(self):
        for command in self.commands:
            command.excute()

    def undo(self):
        for command in self.commands:
            command.undo()


class Light:
    """电灯"""
    name: str

    def __init__(self, name):
        self.name = name

    def off(self):
        print(f'{self.name} is off.')

    def on(self):
        print(f'{self.name} is on.')


class LightOnCommand(Command):
    light: Light

    def __init__(self, light: Light):
        self.light = light

    def excute(self):
        self.light.on()

    def undo(self):
        print('撤销操作，', end='')
        self.light.off()


class LightOffCommand(Command):
    light: Light

    def __init__(self, light: Light):
        self.light = light

    def excute(self):
        self.light.off()

    def undo(self):
        print('撤销操作，', end='')
        self.light.on()


class Stereo:
    """音响"""
    name: str

    def __init__(self, name):
        self.name = name

    def 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: Stereo

    def __init__(self, stereo: Stereo):
        self.stereo = stereo

    def 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: Stereo

    def __init__(self, stereo: Stereo):
        self.stereo = stereo

    def 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: 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)
        self.undo_command = no_command

    def set_command(self, slot: int, on_command: Command, off_command: Command):
        self.on_commands[slot] = on_command
        self.off_commands[slot] = off_command

    def 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

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