假设想让遥控器控制电灯的开关、电视机的开关和切换，该如何做？
所有的开、关、切换都是遥控器发出的指令，把这些指令统一抽象成一个接口。
public interface IControl{void Execute();}
把电灯、电视机抽象成类。
public class Tv{public void TurnOn(){Console.WriteLine("电视机打开了");}public void TurnOff(){Console.WriteLine("电视机关闭了");}public void SwitchChannel(){Console.WriteLine("电视机切换频道");}}public class Light{public void TunrOn(){Console.WriteLine("电灯打开了");}public void TurnOff(){Console.WriteLine("电灯关闭了");}}
Tv类的TurnOn(),TurnOff(),SwitchChannel(),Light类的TurnOn(),TurnOff()，这些方法都会通过执行IController的Execute方法被触发。把每一种动作抽象成类，并实现IControl接口。
public class LighOn : IControl{private Light _light;public LighOn(Light light){_light = light;}public void Execute(){_light.TunrOn();}}public class LightOff : IControl{private Light _light;public LightOff(Light light){_light = light;}public void Execute(){_light.TurnOff();}}public class TvOn : IControl{private Tv _tv;public TvOn(Tv tv){_tv = tv;}public void Execute(){_tv.TurnOn();}}public class TvOff : IControl{private Tv _tv;public TvOff(Tv tv){_tv = tv;}public void Execute(){_tv.TurnOff();}}public class TvSwitch : IControl{private Tv _tv;public TvSwitch(Tv tv){_tv = tv;}public void Execute(){_tv.SwitchChannel();}}
现在，电视机和电灯有了，触发各种动作的类有了，遥控器该装下这些指令(提供装下指令的方法)并提供方法供客户端调用。
public class RemoteControl{private IList<IControl> onCommands = new List<IControl>();private IList<IControl> offCommands = new List<IControl>();private IList<IControl> switchCommands = new List<IControl>();public void AddOnCommand(IControl control){onCommands.Add(control);}public void AddOffCommand(IControl control){offCommands.Add(control);}public void AddSwitchCommand(IControl control){switchCommands.Add(control);}public void PressOnButton(int number){onCommands[number].Execute();}public void PressOffButton(int number){offCommands[number].Execute();}public void PressSwitchButton(int number){switchCommands[number].Execute();}}
客户端的执行逻辑大致是：把电视机、电灯准备好，把各种指令准备好，拿出遥控器把各种指令收纳其中，最后调用遥控器的方法执行各种指令。
class Program{static void Main(string[] args){//命令的接收方Light light = new Light();Tv tv = new Tv();//各种命令LighOn turnLightOn = new LighOn(light);LightOff turnLightOff = new LightOff(light);TvOn turnTvOn = new TvOn(tv);TvOff turnTvOff = new TvOff(tv);TvSwitch switchTv = new TvSwitch(tv);//RemoteConroller组装命令RemoteControl control = new RemoteControl();control.AddOnCommand(turnLightOn);control.AddOnCommand(turnTvOn);control.AddOffCommand(turnLightOff);control.AddOffCommand(turnTvOff);control.AddSwitchCommand(switchTv);control.PressOnButton(0);Console.ReadKey();}}
总结：命令模式的需求源自想通过一个指令(比如这里IControl的Execute方法)来控制多个类的多个方法，包含了几个要素：
1、命令：让类的各种方法抽象成类实现一个接口
2、装配命令：把各种命令放到一个集合中
3、触发命令：提供方法调用命令集合中的某条命令，让其执行指令
时间： 2024-11-08 23:32:10