Unity实现设计模式——状态模式

状态模式最核心的设计思路就是将对象的状态抽象出一个接口，然后根据它的不同状态封装其行为，这样就可以实现状态和行为的绑定，最终实现对象和状态的有效解耦。

在实际开发中一般用到FSM有限状态机的实现，GF框架中的FSM和流程控制就是基于这个原理实现的。

1.State（状态的抽象基类）

    public abstract class State{protected Context m_Context = null;public State(Context theContext){m_Context = theContext;}public abstract void Handle(int Value);}

2.ConcreteStateA，ConcreteStateB，ConcreteStateC

状态State的子类

    /// <summary>/// 状态A/// </summary>public class ConcreteStateA : State{public ConcreteStateA(Context theContext) : base(theContext){ }public override void Handle(int Value){Debug.Log("ConcreteStateA.Handle");if (Value > 10)m_Context.SetState(new ConcreteStateB(m_Context));}}/// <summary>/// 状态B/// </summary>public class ConcreteStateB : State{public ConcreteStateB(Context theContext) : base(theContext){ }public override void Handle(int Value){Debug.Log("ConcreteStateB.Handle");if (Value > 20)m_Context.SetState(new ConcreteStateC(m_Context));}}/// <summary>/// 状态C/// </summary>public class ConcreteStateC : State{public ConcreteStateC(Context theContext) : base(theContext){ }public override void Handle(int Value){Debug.Log("ConcreteStateC.Handle");if (Value > 30)m_Context.SetState(new ConcreteStateA(m_Context));}}

3.Context

Context类-持有目前的状态,并将相关信息传给状态

    public class Context{State m_State = null;public void Request(int Value){m_State.Handle(Value);}public void SetState(State theState){Debug.Log("Context.SetState:" + theState);m_State = theState;}}

4.测试代码

    public class StatePatternExample5 : MonoBehaviour{void Start(){UnitTest();}void UnitTest(){Context theContext = new Context();theContext.SetState(new ConcreteStateA(theContext));theContext.Request(5);theContext.Request(15);theContext.Request(25);theContext.Request(35);}}