示例一：
public class SpiderService { private static SpiderService instance; public static SpiderService Instance { get { if (instance == null) { instance = new SpiderService(); } return instance; } } }
通过SpiderService.Instance访问方法。
示例二：
public sealed class Singleton { private static readonly Lazy<Singleton6> lazy = new Lazy<Singleton>(()=> new Singleton()); public static Singleton Instance { get { return lazy.Value; } } private Singleton() { } }