我即将使用状态模式在 C# 中实现分层状态机。作为一个指南，我正在使用这个例子。但是，该示例并未提供有关分层状态的答案。不幸的是，我似乎无法在其他地方找到好的例子。我的第一个想法是为分层状态创建嵌套类。但这被认为是最佳实践还是有更好的解决方案？
问候！
更新：
我整个下午都在尝试实现上述状态模式。HSM 基于一个非常简单的媒体播放器：
替代文字 http://www.freeimagehosting.net/uploads/e8d2d6486a.jpg
我以为我已经做到了，但有一件事我不明白。首先是我写的代码（对不起，很多）：
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();
}
}
在 MediaPlayer 类中定义事件时，我不能调用任何其他函数
- OnButtonPressed
- OffButtonPressed
所以我想知道，我的实施有什么好处吗？怎么了？我还尝试查看使用复合模式的建议，但我不明白它应该如何与状态模式一起使用。希望任何人都可以提供帮助！