单例模式的线程安全

新建一个object，使用lock关键字对其进行线程安全的保护

public class Singleton
{
    private static readonly object syncLock = new Object();
　　 private static Singleton instance = null;
    public static Singleton Instance
    {
        get
        {
            if (instance == null)
            {
                lock (syncLock)
                {
                    if (instance == null)
                    {
                        instance = new Singleton();
                    }
                }
            }
            return instance;
        }
    }
}