Singleton Pattern Unity 创建多个副本

Question

我正在尝试使用单例模式来监控 Unity 项目的统计信息。我正在使用下面的课程。我遇到的问题是，我的代码似乎不是只有一个单例，而是为我调用单例函数的每个实例创建一个单例。例如，每次玩家开枪时，我都会拨打ShootingStats.Instance.incrementTotalShotsFired();。如果我总共有三个玩家，我的代码似乎会生成三个 ShootingStats 单曲 - 每个玩家一个。我想要实现的是只有一个类来监控所有玩家的这些统计数据，而不是每个玩家一个。 我找到了单例代码：http://wiki.unity3d.com/index.php/Singleton。我是 Unity 新手，但在编程方面很有经验。我最初尝试使用一个非常简单的 Singleton 模式版本，就像有人在 C# 中使用的那样，但它没有按预期工作。相反，每次我访问其中一个单例方法时，它都会创建一个新对象。非常感谢您提前提供的帮助。

单例类

using UnityEngine;

/// <summary>
/// Be aware this will not prevent a non singleton constructor
///   such as `T myT = new T();`
/// To prevent that, add `protected T () {}` to your singleton class.
/// 
/// As a note, this is made as MonoBehaviour because we need Coroutines.
/// </summary>
namespace Porject.Statistics
{
    public class Singleton<T> : MonoBehaviour where T : MonoBehaviour
    {
        private static T _instance;

        private static object _lock = new object();

        public static T Instance
        {
            get
            {
                if (applicationIsQuitting)
                {
                    //Debug.LogWarning("[Singleton] Instance '" + typeof(T) +
                    //  "' already destroyed on application quit." +
                    //  " Won't create again - returning null.");
                    return null;
                }

                lock (_lock)
                {
                    if (_instance == null)
                    {
                        _instance = (T)FindObjectOfType(typeof(T));

                        if (FindObjectsOfType(typeof(T)).Length > 1)
                        {
                            //Debug.LogError("[Singleton] Something went really wrong " +
                            //  " - there should never be more than 1 singleton!" +
                            //  " Reopening the scene might fix it.");
                            return _instance;
                        }

                        if (_instance == null)
                        {
                            GameObject singleton = new GameObject();
                            _instance = singleton.AddComponent<T>();
                            singleton.name = "(singleton) " + typeof(T).ToString();

                            DontDestroyOnLoad(singleton);

                            //Debug.Log("[Singleton] An instance of " + typeof(T) +
                            //  " is needed in the scene, so '" + singleton +
                            //  "' was created with DontDestroyOnLoad.");
                        }
                        else
                        {
                            //Debug.Log("[Singleton] Using instance already created: " +
                            //  _instance.gameObject.name);
                        }
                    }

                    return _instance;
                }
            }
        }

        private static bool applicationIsQuitting = false;

        /// <summary>
        /// When Unity quits, it destroys objects in a random order.
        /// In principle, a Singleton is only destroyed when application quits.
        /// If any script calls Instance after it have been destroyed, 
        ///   it will create a buggy ghost object that will stay on the Editor scene
        ///   even after stopping playing the Application. Really bad!
        /// So, this was made to be sure we're not creating that buggy ghost object.
        /// </summary>
        public void OnDestroy()
        {
            applicationIsQuitting = true;
        }
    }
}

ShootingStats 类

using UnityEngine;
using System.Collections;
using Project.Statistics;

namespace Project.Statistics
{
    public class ShootingStats : Singleton<ShootingStats>
    {

        private int _onTarget = 0;
        private int _totalShotsFired = 0;

        protected ShootingStats() { }

        public void incrementOnTarget()
        {
            _onTarget++;
        }

        public void incrementTotalShotsFired()
        {
            _totalShotsFired++;
        }

        public void printStats()
        {
            string lines = "Total shots fired: " + _totalShotsFired + "\n" + "Shots on target: " + _onTarget + "\n.";
            Debug.Log(lines);
        }
    }
}

MethodExtensionForMonoBehaviourTransform 类 - 不确定这是什么

using UnityEngine;

static public class MethodExtensionForMonoBehaviourTransform
{
    /// <summary>
    /// Gets or add a component. Usage example:
    /// BoxCollider boxCollider = transform.GetOrAddComponent<BoxCollider>();
    /// </summary>
    static public T GetOrAddComponent<T>(this Component child) where T : Component
    {
        T result = child.GetComponent<T>();
        if (result == null)
        {
            result = child.gameObject.AddComponent<T>();
        }
        return result;
    }
}

Answer 1

您可以通过更简单的方式为 GameObject 实现单例模式行为：

private static GameControllerBehaviour instance;

void Awake(){

    //SINGLETON PATTERN

    if (GameControllerBehaviour.instance == null){
        DontDestroyOnLoad (this);
        GameControllerBehaviour.instance = this;

    } else {
        Destroy (this.gameObject);
    }
}