C#数据结构-有限状态机
发表于2018-09-20
有限状态机FSM的要点是：
1.拥有一组状态，并且可以在这组状态之间进行切换。
2.状态机同时只能在一个状态。
3.一连串的输入或事件被发送给机器。
4.每个状态都有一系列的转换，转换与输入和另一状态相关。当输入进来，如果它与当前状态的某个转换匹配，机器转为转换所指的状态。
目前而言，游戏编程中状态机的实现方式，有两种可以选择：
1.用枚举配合switch case语句。
2.实现多态（也就是状态模式）。
状态模式的经典定义：允许对象在当内部状态改变时改变其行为，就好像此对象改变了自己的类一样。
状态模式的实现要点，主要有三点：
1.为状态定义一个接口。
2.为每个状态定义一个类。
3.恰当地进行状态委托。
注：下面的代码在unity中用C#实现，不过只是借用了unity的输入操作，对于理解有限状态机，没有阻碍。
初始化是站立状态；
1.按下向上的方向键，可以跳跃；在跳跃的状态，按向下的方向键，可以下斩，按向上的方向键，不做处理；
2.按下向下的方向键，可以下蹲；在下蹲的状态，按向下的方向键，不做处理，按向上的方向键，恢复站立状态；
状态接口实现：
public interface HeroineBaseState
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void HandleInput();
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站立状态实现：
using UnityEngine;
public class StandingState : HeroineBaseState
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private Heroine _heroine;
public StandingState(Heroine heroine)
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_heroine = heroine;
Debug.Log("进入站立状态！");
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public void HandleInput()
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if (Input.GetKeyDown(KeyCode.UpArrow))
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Debug.Log("get KeyCode.UpArrow!");
_heroine.SetHeroineState(new JumpingState(_heroine));
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if (Input.GetKeyDown(KeyCode.DownArrow))
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Debug.Log("get KeyCode.DownArrow!");
_heroine.SetHeroineState(new DuckingState(_heroine));
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跳跃状态实现：
using UnityEngine;
public class JumpingState : HeroineBaseState
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private Heroine _heroine;
public JumpingState(Heroine heroine)
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_heroine = heroine;
Debug.Log("进入跳跃状态！");
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public void HandleInput()
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if (Input.GetKeyDown(KeyCode.UpArrow))
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Debug.Log("已经在跳跃状态中！");
return;
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if (Input.GetKeyDown(KeyCode.DownArrow))
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Debug.Log("get KeyCode.DownArrow!");
_heroine.SetHeroineState(new DrivingState(_heroine));
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下蹲状态实现：
using UnityEngine;
public class DuckingState : HeroineBaseState
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private Heroine _heroine;
public DuckingState(Heroine heroine)
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_heroine = heroine;
Debug.Log("进入下蹲躲避状态！");
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public void HandleInput()
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if (Input.GetKeyDown(KeyCode.DownArrow))
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Debug.Log("已经在下蹲躲避状态中！");
return;
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if (Input.GetKeyUp(KeyCode.UpArrow))
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Debug.Log("get GetKeyUp.UpArrow!");
_heroine.SetHeroineState(new StandingState(_heroine));
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下斩状态实现：
using UnityEngine;
public class DrivingState : HeroineBaseState
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private Heroine _heroine;
public DrivingState(Heroine heroine)
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_heroine = heroine;
Debug.Log("进入下斩状态！");
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public void HandleInput()
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if (Input.GetKeyDown(KeyCode.UpArrow))
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Debug.Log("get KeyCode.UpArrow!");
_heroine.SetHeroineState(new StandingState(_heroine));
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女主角实现：
public class Heroine
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HeroineBaseState _state;
public Heroine()
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_state = new StandingState(this);
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public void SetHeroineState(HeroineBaseState newState)
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_state = newState;
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public void Update()
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_state.HandleInput();
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测试代码，在Unity里要挂在一个GameObject上执行。
using UnityEngine;
public class TestHeroine : MonoBehaviour
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private Heroine _heroine;
// 初始化调用，先执行
void Start()
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_heroine = new Heroine();
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// 每帧调用一次
void Update()
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_heroine.Update();
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上面用的接口，还可以用虚函数或者抽象函数来实现多态。下面模拟了银行存款取款，账户的状态的变化。
C#代码实现：
using System;
namespace StructScript
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public class StateScript
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static void Main(string[] args)
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Account account = new Account();
account.Add(500);
account.Add(3000);
account.Remove(1000);
account.Remove(10000);
Console.ReadLine();
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public class Account
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private State state;
public Account()
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state = new RedState(0.0, this);
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public State State
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get ｛ return state; ｝
set ｛ state = value; ｝
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public void Add(int amount)
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Console.WriteLine("Add " + amount);
state.Add(amount);
Console.WriteLine("Balance: " + state.Balance);
Console.WriteLine("State: " + state.GetType().Name);
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public void Remove(int amount)
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Console.WriteLine("Remove " + amount);
state.Remove(amount);
Console.WriteLine("Balance: " + state.Balance);
Console.WriteLine("State: " + state.GetType().Name);
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/// <summary>
/// 状态基类
/// </summary>
public abstract class State
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protected Account account;
protected double balance;
protected double lowerLimit;
protected double upperLimit;
public Account Account
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get ｛ return account; ｝
set ｛ account = value; ｝
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public double Balance
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get ｛ return balance; ｝
set ｛ balance = value; ｝
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public abstract void Add(int amount);
public abstract void Remove(int amount);
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/// <summary>
/// 红色账户状态
/// </summary>
public class RedState : State
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public RedState(State state) : this(state.Balance, state.Account) ｛ ｝
public RedState(double balance, Account account)
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this.balance = balance;
this.account = account;
lowerLimit = -100.0;
upperLimit = 0.0;
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public override void Add(int amount)
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balance += amount;
StateChangeCheck();
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public override void Remove(int amount)
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Console.WriteLine("余额不足");
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private void StateChangeCheck()
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if (balance > upperLimit)
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account.State = new SilverState(this);
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/// <summary>
/// 银色账户状态
/// </summary>
public class SilverState : State
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public SilverState(State state) : this(state.Balance, state.Account) ｛ ｝
public SilverState(double balance, Account account)
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this.balance = balance;
this.account = account;
lowerLimit = 0.0;
upperLimit = 1000.0;
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public override void Add(int amount)
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balance += amount;
StateChangeCheck();
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public override void Remove(int amount)
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double remain = balance - amount;
if (remain < -100)
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Console.WriteLine("余额不足");
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else
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balance = remain;
StateChangeCheck();
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private void StateChangeCheck()
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if (balance < lowerLimit)
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account.State = new RedState(this);
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else if (balance > upperLimit)
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account.State = new GoldState(this);
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/// <summary>
/// 金色账户状态
/// </summary>
public class GoldState : State
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public GoldState(State state) : this(state.Balance, state.Account) ｛ ｝
public GoldState(double balance, Account account)
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this.balance = balance;
this.account = account;
lowerLimit = 1000.0;
upperLimit = 10000000.0;
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public override void Add(int amount)
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balance += amount;
StateChangeCheck();
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public override void Remove(int amount)
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double remain = balance - amount;
if (remain < -100)
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Console.WriteLine("余额不足");
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else
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balance = remain;
StateChangeCheck();
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private void StateChangeCheck()
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if (balance < 0.0)
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account.State = new RedState(this);
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else if (balance < lowerLimit)
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account.State = new SilverState(this);
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来自：https://blog.csdn.net/qq826364410/article/details/79827022