设计模式

 1     class Program
 2     {
 3         static void Main(string[] args)
 4         {
 5             Console.WriteLine("此时没有输出“构造函数”");
 6             Singleton s1 = Singleton.getInstance();
 7             Console.WriteLine("输出“构造函数”完成了");
 8         }
 9     }
10     public class Singleton
11     {
12         private Singleton()
13         {
14             Console.WriteLine("构造函数");
15         }
16 
17         private static class HolderClass
18         {
19             public readonly static Singleton instance = new Singleton();
20         }
21 
22         public static Singleton getInstance()
23         {
24             return HolderClass.instance;
25         }
26     }