[其他] 自定义状态机的实现

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王者再临

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发表于 2015-10-13 07:24:57 |只看该作者 |倒序浏览

关于状态机，我想都知道它很常用，就像单例一样，我们基本上每个项目都会用到它。网上也有很多大神写的状态机，比如 PlayMaker 这样重量级的插件，功能很强大，依赖也很多。不过，程序猿的胃口有时候就是很挑剔，吃惯了大鱼大肉的东西，总想吃点清粥小菜。应该有很多朋友跟我一样，希望有一套轻量级的状态机实现，每行代码自己都了如指掌，实现我们一些简单的状态控制的需求。In hand（伸手就来的方便），你也有这种共鸣么？

下面是我的实现，有不足或者 low的地方，希望告诉我，一起进步吧！

状态机类：

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
namespace PLY.StateMachine {
/// <summary>
/// 有限状态机基类.
/// </summary>
[System.Serializable]
public class FiniteStateMachine : MonoBehaviour {
private object Context_;
public string CurrentStateName = "EmptyState";
private FiniteState CurrentState_;
protected FiniteState CurrentState{
get{
return CurrentState_;
}
set{
CurrentState_ = value;
CurrentStateName = CurrentState_.Name;
}
}
protected FiniteState defaultState;
private Dictionary<string, FiniteState> allStates_ = new Dictionary<string, FiniteState>();
private List<FiniteStateTransition> allTransitions_ = new List<FiniteStateTransition>();
protected virtual void Init(){}
protected void AddState(FiniteState state){
allStates_.Add(state.Name, state);
}
protected void RemoveState(FiniteState state){
allStates_.Remove(state.Name);
}
/// <summary>
/// 添加过渡.
/// </summary>
/// <param name="eventName">Event name.</param>
/// <typeparam name="T1">源状态类型.</typeparam>
/// <typeparam name="T2">目标状态类型.</typeparam>
protected void AddTransition<T1,T2>(string eventName){
string lastStateName = typeof(T1).Name;
string nextStateName = typeof(T2).Name;
FiniteStateTransition transition = new FiniteStateTransition(eventName, lastStateName, nextStateName );
allTransitions_.Add(transition);
}
protected void AddTransition(FiniteStateTransition transition){
allTransitions_.Add(transition);
}
protected void RemoveTransation(FiniteStateTransition transition){
allTransitions_.Remove(transition);
}
public void SetContext(object context){
Context_ = context;
}
/// <summary>
/// 发送事件，触发下一状态的切换
/// </summary>
/// <param name="eventName">事件名.</param>
public void SendEvent(string eventName){
for (int i = 0; i < allTransitions_.Count; i++) {
FiniteState nextState;
if (TryGetNextStateByEventName(allTransitions_[i], eventName, out nextState)){
ChangeState(nextState);
break;
}
}
}
private bool TryGetNextStateByEventName(FiniteStateTransition transation, string eventName, out FiniteState state){
state = null;
if (CurrentState == null || !CurrentState.Name.Equals(transation.LastStateName)) return false;
if (!eventName.Equals(transation.EventName)) return false;
return (allStates_.TryGetValue(transation.NextStateName, out state));
}
/// <summary>
/// 切换状态.
/// </summary>
/// <param name="newState">New state.</param>
private void ChangeState(FiniteState newState){
if (CurrentState != null){
CurrentState.OnExit(Context_);
}
else{
Debug.LogError("当前状态为空，退出状态失败！", gameObject);
}
CurrentState = newState;
if(CurrentState != null){
CurrentState.OnEnter(Context_);
}
else{
Debug.LogError("当前状态为空，进入状态失败！", gameObject);
}
}
private void SetDefaultToCurrent(){
CurrentState = defaultState;
}
private void Awake(){
Init();
SetDefaultToCurrent();
}
private void Start () {
if (CurrentState != null){
CurrentState.OnEnter(Context_);
}
}
private void Update () {
if (CurrentState != null){
CurrentState.OnUpdate(Context_);
}
}
private void FixedUpdate(){
if (CurrentState != null){
CurrentState.OnFixedUpdate(Context_);
}
}
private void LateUpdate(){
if (CurrentState != null){
CurrentState.OnLateUpdate(Context_);
}
}
}
}

复制代码

Transition 和状态基类：

using UnityEngine;
using System.Collections;
namespace PLY.StateMachine{
/// <summary>
/// 状态机过渡约束基类.
/// </summary>
public class FiniteStateTransition {
public string EventName;
public string LastStateName;
public string NextStateName;
public FiniteStateTransition(string eventName, string lastStateName, string nextStateName){
EventName = eventName;
LastStateName = lastStateName;
NextStateName = nextStateName;
}
}
/// <summary>
/// 状态基类.
/// </summary>
public class FiniteState {
public string Name {
get {
return GetType().Name;
}
}
public virtual void OnEnter(object context){}
public virtual void OnExit(object context){}
public virtual void OnUpdate(object context){}
public virtual void OnFixedUpdate(object context){}
public virtual void OnLateUpdate(object context){}
}
}