Design Patterns-Command Patterns

將一個請求封裝為物件，讓你可用不同的請求對客戶進行參數化。對請求排隊或記錄請求日誌，以及支援可取消的操作。

KinectManager:

   1: public class KinectManager

   2: {

   3:     public void KinectWave()

   4:     {

   5:         Console.WriteLine("Doing WaveGesture");

   6:     }

   7:     public void KinectHold()

   8:     {

   9:         Console.WriteLine("Doing HoldGesture");

  10:     }

  11: }

Client:

   1: static void Main(string[] args)

   2: {

   3:     KinectManager kinectManager = new KinectManager()

   4:     kinectManager.KinectWave();

   5:     kinectManager.KinectHold();

   6:     kinectManager.KinectWave();

   7:     kinectManager.KinectWave();

   8:     kinectManager.KinectHold();

   9:     Console.Read();

  10:  

  11: }

當執行命令時，皆要透過kinectManager，當命令變多時則就容易肇成混亂。(有如客人直接向廚師點菜，廚師不只要炒菜還要處理客人點的菜單) 緊耦合的設計。

Command:

   1: public abstract class Command

   2: {

   3:     protected KinectManager receiver;

   4:     pulbic Command(KinectManager receiver)

   5:     {

   6:         this.receiver = receiver;

   7:     }

   8:     abstract public void ExcuteCommand();

   9: }

WaveCommand:

   1: class WaveCommand : Command

   2: {

   3:     public WaveCommand(KinectManager receiver)

   4:         :base(receiver){}

   5:     

   6:     public override void ExcuteCommand()

   7:     {

   8:         receiver.KinectWave();

   9:     }

  10: }

HoldCommand:

   1: class HoldCommand : Command

   2: {

   3:     public HoldCommand(KinectManager receiver)

   4:         :base(receiver){}

   5:     pulibc override void ExcuteCommand()

   6:     {

   7:         receiver.KinectHold();

   8:     }

   9: }

Service:

   1: public class Service

   2: {

   3:     private Command command;

   4:     public void SetOrder(Command command)

   5:     {

   6:         thos.command = command;

   7:     }

   8:     public void NotifyCommand()

   9:     {

  10:         command.ExcuteCommand();

  11:     }

  12: }

KinectManager:Same as above

再來考慮到Service可能需要取消Command且，若Command 是一連續判斷(在Kinect 可能需要把Gesture分解成數個Part)因此，還要再修改Service:

   1: public class Service

   2: {

   3:     private IList<Command> orders = new List<Command>();

   4:  

   5:     public void SetOrder(Command command)

   6:     {

   7:         if(Command can be add)

   8:             orddes.Add(command);

   9:         else

  10:             //some problem so Command can't be excute

  11:     }

  12:     

  13:     public void CancelOrder(Command command)

  14:     {

  15:         orders.Remove(command);

  16:     }

  17:     

  18:     public void NotifyCommand()

  19:     {

  20:         foreach(Command cmd in orders)

  21:             cmd.ExcuteCommand();

  22:     }

  23: }

Client:

   1: static void Main(string[]  args)

   2: {

   3:     KinectManager kinectManager = new KinectManager();

   4:     Command waveCommand1 = new WaveCommand(kinectManager);

   5:     Command waveCommand2 = new WaveCommand(kinectManager);

   6:     Command holdCommand = new HoldCommand(kinectManager);

   7:     

   8:     Service serviceOrder = new Service();

   9:     serviceOrder.SetOrder(waveCommand1);

  10:     serviceOrder.SetOrder(waveCommand2);

  11:     serviceOrder.SetOrder(holdCommand1);

  12:     

  13:     service.NotifyCommand();

  14:     Console.Read();

  15:     

  16: }

在Kinect的姿勢判斷，可以將動作分為數個檢查點，假設一個Wave的Gesture分成兩個Part(兩個Command)，當如果IList 存取的東西為依序的兩個Part 代表這一連串動作辨識是成功，則Excute Wave Gesture 的行為。

 

Command Pattern:

優點:

1.容易設計一個命令的佇列。

2.容易將命令記入到日誌(List)。

3.接收請求的一方決定是否要否決或接受。

4.加入新的具體命令不影響其他命令(Encapsulation)。