单例抽象类

Singleton.cs

public abstract class Singleton<T> where T : class, new()
{
    private static readonly object LockObject = new object();
    private static T _instance;

    public static T Instance
    {
        get
        {
            if (_instance != null) return _instance;

            lock (LockObject)
            {
                if (_instance == null)
                    _instance = new T();
            }

            return _instance;
        }
    }

    public void Free()
    {
        _instance = null;
        FreeSingleton();
    }

    protected virtual void FreeSingleton()
    {
    }
}