using System;
using UnityEngine;

public class MonoSingletonDontDestory<T> : MonoBehaviour where T : MonoBehaviour
{
    protected static T _insatnce;
    protected static object _lock = new object();

    public static T Instance
    {
        get
        {
            lock (_lock)
            {
                if (_insatnce == null)
                {
                    var instances = FindObjectsOfType<T>();
                    if (instances.Length > 1)
                    {
                        throw new Exception(string.Format("场景中存在多个类型为:{0}的脚本", typeof(T).ToString()));
                    }
                    else if (instances.Length == 0)
                    {
                        var go = new GameObject(typeof(T).ToString() + "(MonoSingleton)");
                        _insatnce = go.AddComponent<T>();
                        DontDestroyOnLoad(go);
                    }
                    else
                    {
                        _insatnce = instances[0];
                    }
                }
                return _insatnce;
            }
        }
    }

    protected virtual void OnApplicationQuit()
    {
        _insatnce = null;
    }

    protected virtual void OnDestory()
    {
        _insatnce = null;
    }
}