基于 MonoBehaviour ScriptableObject 的 Singleton 类
大多数 Singleton 示例使用 MonoBehaviour 作为基类。主要缺点是这个 Singleton 类仅在运行时存在。这有一些缺点：
- 除了更改代码之外，无法直接编辑单例字段。
- 无法在 Singleton 上存储对其他资产的引用。
- 无法将单例设置为 Unity UI 事件的目标。我最终使用我称之为代理组件的东西，它唯一的建议是使用一行调用“
GameManager.Instance.SomeGlobalMethod()”的方法。
正如备注中所述，有些实现试图使用 ScriptableObjects 作为基类来解决这个问题，但却失去了 MonoBehavi 的运行时优势。此实现通过在运行时使用 ScriptableObject 作为基类和关联的 MonoBehavior 来解决此问题：
- 它是一种资产，因此可以像编辑任何其他 Unity 资产一样在编辑器上更新其属性。
- 它与 Unity 序列化过程很好地配合。
- 可以将单例的引用分配给编辑器中的其他资源（依赖项通过编辑器注入）。
- Unity 事件可以直接调用 Singleton 上的方法。
- 可以使用“SingletonClassName.Instance”从代码库中的任何位置调用它
- 可以访问运行时 MonoBehaviour 事件和方法，如：Update，Awake，Start，FixedUpdate，StartCoroutine 等。
/************************************************************
* Better Singleton by David Darias
* Use as you like - credit where due would be appreciated :D
* Licence: WTFPL V2, Dec 2014
* Tested on Unity v5.6.0 (should work on earlier versions)
* 03/02/2017 - v1.1
* **********************************************************/
using System;
using UnityEngine;
using SingletonScriptableObjectNamespace;
public class SingletonScriptableObject<T> : SingletonScriptableObjectNamespace.BehaviourScriptableObject where T : SingletonScriptableObjectNamespace.BehaviourScriptableObject
{
//Private reference to the scriptable object
private static T _instance;
private static bool _instantiated;
public static T Instance
{
get
{
if (_instantiated) return _instance;
var singletonName = typeof(T).Name;
//Look for the singleton on the resources folder
var assets = Resources.LoadAll<T>("");
if (assets.Length > 1) Debug.LogError("Found multiple " + singletonName + "s on the resources folder. It is a Singleton ScriptableObject, there should only be one.");
if (assets.Length == 0)
{
_instance = CreateInstance<T>();
Debug.LogError("Could not find a " + singletonName + " on the resources folder. It was created at runtime, therefore it will not be visible on the assets folder and it will not persist.");
}
else _instance = assets[0];
_instantiated = true;
//Create a new game object to use as proxy for all the MonoBehaviour methods
var baseObject = new GameObject(singletonName);
//Deactivate it before adding the proxy component. This avoids the execution of the Awake method when the the proxy component is added.
baseObject.SetActive(false);
//Add the proxy, set the instance as the parent and move to DontDestroyOnLoad scene
SingletonScriptableObjectNamespace.BehaviourProxy proxy = baseObject.AddComponent<SingletonScriptableObjectNamespace.BehaviourProxy>();
proxy.Parent = _instance;
Behaviour = proxy;
DontDestroyOnLoad(Behaviour.gameObject);
//Activate the proxy. This will trigger the MonoBehaviourAwake.
proxy.gameObject.SetActive(true);
return _instance;
}
}
//Use this reference to call MonoBehaviour specific methods (for example StartCoroutine)
protected static MonoBehaviour Behaviour;
public static void BuildSingletonInstance() { SingletonScriptableObjectNamespace.BehaviourScriptableObject i = Instance; }
private void OnDestroy(){ _instantiated = false; }
}
// Helper classes for the SingletonScriptableObject
namespace SingletonScriptableObjectNamespace
{
#if UNITY_EDITOR
//Empty custom editor to have cleaner UI on the editor.
using UnityEditor;
[CustomEditor(typeof(BehaviourProxy))]
public class BehaviourProxyEditor : Editor
{
public override void OnInspectorGUI(){}
}
#endif
public class BehaviourProxy : MonoBehaviour
{
public IBehaviour Parent;
public void Awake() { if (Parent != null) Parent.MonoBehaviourAwake(); }
public void Start() { if (Parent != null) Parent.Start(); }
public void Update() { if (Parent != null) Parent.Update(); }
public void FixedUpdate() { if (Parent != null) Parent.FixedUpdate(); }
}
public interface IBehaviour
{
void MonoBehaviourAwake();
void Start();
void Update();
void FixedUpdate();
}
public class BehaviourScriptableObject : ScriptableObject, IBehaviour
{
public void Awake() { ScriptableObjectAwake(); }
public virtual void ScriptableObjectAwake() { }
public virtual void MonoBehaviourAwake() { }
public virtual void Start() { }
public virtual void Update() { }
public virtual void FixedUpdate() { }
}
}
这里有一个使用 SingletonScriptableObject（有很多注释）的 GameManager 单例类示例：
using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
//this attribute is optional but recommended. It will allow the creation of the singleton via the asset menu.
//the singleton asset should be on the Resources folder.
[CreateAssetMenu(fileName = "GameManager", menuName = "Game Manager", order = 0)]
public class GameManager : SingletonScriptableObject<GameManager> {
//any properties as usual
public int Lives;
public int Points;
//optional (but recommended)
//this method will run before the first scene is loaded. Initializing the singleton here
//will allow it to be ready before any other GameObjects on every scene and will
//will prevent the "initialization on first usage".
[RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.BeforeSceneLoad)]
public static void BeforeSceneLoad() { BuildSingletonInstance(); }
//optional,
//will run when the Singleton Scriptable Object is first created on the assets.
//Usually this happens on edit mode, not runtime. (the override keyword is mandatory for this to work)
public override void ScriptableObjectAwake(){
Debug.Log(GetType().Name + " created." );
}
//optional,
//will run when the associated MonoBehavioir awakes. (the override keyword is mandatory for this to work)
public override void MonoBehaviourAwake(){
Debug.Log(GetType().Name + " behaviour awake." );
//A coroutine example:
//Singleton Objects do not have coroutines.
//if you need to use coroutines use the atached MonoBehaviour
Behaviour.StartCoroutine(SimpleCoroutine());
}
//any methods as usual
private IEnumerator SimpleCoroutine(){
while(true){
Debug.Log(GetType().Name + " coroutine step." );
yield return new WaitForSeconds(3);
}
}
//optional,
//Classic runtime Update method (the override keyword is mandatory for this to work).
public override void Update(){
}
//optional,
//Classic runtime FixedUpdate method (the override keyword is mandatory for this to work).
public override void FixedUpdate(){
}
}
/*
* Notes:
* - Remember that you have to create the singleton asset on edit mode before using it. You have to put it on the Resources folder and of course it should be only one.
* - Like other Unity Singleton this one is accessible anywhere in your code using the "Instance" property i.e: GameManager.Instance
*/