Alex教程每一P的教程原代码加上我自己的理解初步理解写的注释，可供学习Alex教程的人参考
此代码仅为较上一P有所改变的代码

【Unity教程】从0编程制作类银河恶魔城游戏_哔哩哔哩_bilibili

Enemy.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Enemy : MonoBehaviour
{
    #region 组件
    public Animator anim { get; private set; }
    public Rigidbody2D rb { get; private set; }
    #endregion
    #region 类
    public EnemyStateMachine stateMachine;
    public EnemyIdleState idleState;
    #endregion

    private void Awake()
    {
        stateMachine = new EnemyStateMachine();
        idleState = new EnemyIdleState(this, stateMachine, "Idle");

        anim = GetComponentInChildren<Animator>();
        rb = GetComponent<Rigidbody2D>();
    }
    void Start()
    {
        stateMachine.Initialize(idleState);
    }

   
    void Update()
    {
        stateMachine.currentState.Update();
    }
}

EnemyState.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class EnemyState
{

    protected Enemy enemy;
    protected EnemyStateMachine stateMachine;

    protected bool triggerCalled;

    private string animBoolName;

    protected float stateTimer;


    public EnemyState(Enemy _enemy, EnemyStateMachine _stateMachine, string _animBoolName)
    {
        this.enemy = _enemy;
        this.stateMachine = _stateMachine;
        this.animBoolName = _animBoolName;
    }
    public virtual void Enter()
    {
        triggerCalled = false;
        Debug.Log("I enter" + animBoolName);

        enemy.anim.SetBool(animBoolName, true);
    }
    public virtual void Update()
    {
        stateTimer -= Time.deltaTime;
        Debug.Log("I'm in " + animBoolName);
    }
    public virtual void Exit()
    {
        enemy.anim.SetBool(animBoolName, false);
    }

    
}

EnemyStateMachine.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class EnemyStateMachine
{
    public EnemyState currentState { get; private set; }//记得加private set，不然很可能会被外部改了
    public void Initialize(EnemyState _startState)
    {
        currentState = _startState;
        currentState.Enter();
    }
    public void ChangeState(EnemyState _newState)
    {
        currentState.Exit();
        currentState = _newState;
        currentState.Enter();
    }
}

EnemyIdleState.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class EnemyIdleState : EnemyState
{
    public EnemyIdleState(Enemy _enemy, EnemyStateMachine _stateMachine, string _animBoolName) : base(_enemy, _stateMachine, _animBoolName)
    {
    }

    public override void Enter()
    {
        base.Enter();
    }

    public override void Exit()
    {
        base.Exit();
    }

    public override void Update()
    {
        base.Update();
    }
}