Я собираюсь реализовать иерархический конечный автомат в C #, используя шаблон состояний. В качестве руководства я использую этот пример. Этот пример не дает ответа относительно иерархических состояний. К сожалению, я не могу найти хороших примеров в другом месте. Моя первая мысль - создать вложенные классы для иерархических состояний. Но считается ли это лучшей практикой или есть лучшие решения?
Поздравил!
UPDATE:
Я сидел весь день, пытаясь реализовать шаблон состояний, как описано выше. HSM основан на очень простом медиаплеере:
альтернативный текст http://www.freeimagehosting.net/uploads/e8d2d6486a.jpg
Я думал, что сделал это, но одну вещь я не понимаю. Сначала код, который я написал (извините, это довольно много):
public class MediaPlayer
{
public MediaPlayerStates state;
public MediaPlayer(MediaPlayerStates state)
{
this.state = state;
}
public void OnButtonPressed()
{
state.OnButtonPressed(this);
}
public void DeviceBooted()
{
state. ?????
}
//Other Functions
}
//The 3 initial states (Start, On, End) know only 2 events.
public abstract class MediaPlayerStates
{
public abstract void OnButtonPressed(MediaPlayer player);
public abstract void OffButtonPressed(MediaPlayer player);
}
//The very beginpoint of the state machine
public class Start : MediaPlayerStates
{
//When hitting the onbutton, the state changes to the OnState state
public override void OnButtonPressed(MediaPlayer player)
{
player.state = new OnState(player);
}
//No need to implement this one
public override void OffButtonPressed(MediaPlayer player)
{
throw new NotImplementedException();
}
}
//OnState implements the 2 events from the MediaPlayerStates abstract class.
public class OnState : MediaPlayerStates
{
//When entered the OnState state, a new entrypoint is creaeted: the Start state
public OnState(MediaPlayer player)
{
player.state = new OnStartState();
}
//The OnState doesn't have a OnButtonPressed event so it doesn't need to be implemented
public override void OnButtonPressed(MediaPlayer player)
{
throw new NotImplementedException();
}
//When hitting the offbutton in the OnState, the new state is End
public override void OffButtonPressed(MediaPlayer player)
{
player.state = new End();
}
//The OnState itself containts 3 events, therefore these need to be implemented by every state whitin the OnState state
public abstract class SubStates : MediaPlayerStates
{
public abstract void DeviceBooted(MediaPlayer player);
public abstract void PlayButtonPressed(MediaPlayer player);
public abstract void StopButtonPressed(MediaPlayer player);
}
//The OnStartState is the pseudoState where the On state starts
public class OnStartState : SubStates
{
//When booted, the state of the player changes to the ShowMediaFileState state
public override void DeviceBooted(MediaPlayer player)
{
player.state = new ShowMediaFileState();
}
//The events below don't need to be implemented since they don't exist.
public override void PlayButtonPressed(MediaPlayer player)
{
throw new NotImplementedException();
}
public override void StopButtonPressed(MediaPlayer player)
{
throw new NotImplementedException();
}
public override void OnButtonPressed(MediaPlayer player)
{
throw new NotImplementedException();
}
public override void OffButtonPressed(MediaPlayer player)
{
throw new NotImplementedException();
}
}
public class ShowMediaFileState : SubStates
{
//This event doesn't exists for this state
public override void DeviceBooted(MediaPlayer player)
{
throw new NotImplementedException();
}
//When hitting the play button in this state, play the mediafile
public override void PlayButtonPressed(MediaPlayer player)
{
player.state = new PlayMediaFileState();
}
//These events also don't exist for this state
public override void StopButtonPressed(MediaPlayer player)
{
throw new NotImplementedException();
}
public override void OnButtonPressed(MediaPlayer player)
{
throw new NotImplementedException();
}
public override void OffButtonPressed(MediaPlayer player)
{
throw new NotImplementedException();
}
}
public class PlayMediaFileState : SubStates
{
//This event doesn't exist for this state
public override void DeviceBooted(MediaPlayer player)
{
throw new NotImplementedException();
}
//This event doesn't exist for this state
public override void PlayButtonPressed(MediaPlayer player)
{
throw new NotImplementedException();
}
//While playing a file and hitting the stopbutton, the state changes to the ShowMediaFileState state
public override void StopButtonPressed(MediaPlayer player)
{
player.state = new ShowMediaFileState();
}
//This event doesn't exist for this state
public override void OnButtonPressed(MediaPlayer player)
{
throw new NotImplementedException();
}
//This event doesn't exist for this state
public override void OffButtonPressed(MediaPlayer player)
{
throw new NotImplementedException();
}
}
}
//The endstate doesn't need any implementation since there cannot occur a event while being off
public class End : MediaPlayerStates
{
public override void OnButtonPressed(MediaPlayer player)
{
throw new NotImplementedException();
}
public override void OffButtonPressed(MediaPlayer player)
{
throw new NotImplementedException();
}
}
При определении событий в классе MediaPlayer я не могу вызывать какие-либо другие функции, кроме
- OnButtonPressed
- OffButtonPressed
Так что мне интересно, насколько хороша моя реализация? Что случилось? Я также попытался взглянуть на предложение использовать составной шаблон, но я не понимаю, как его следует использовать с шаблоном состояний. Надеюсь, что кто-нибудь может помочь!