设计模式(一):单例

 1         /// <summary>
 2         /// 饿汉单例模式:类被加载时,将自己类实例化(静态初始化)
 3         /// </summary>
 4         public sealed class Singleton1
 5         {
 6             private static readonly Singleton1 instance = new Singleton1();
 7             private Singleton1()
 8             { }
 9 
10             public static Singleton1 GetInstance()
11             {
12                 return instance;
13             }
14         }
15 
16         /// <summary>
17         /// 懒汉单例模式:类第一次被引用时,将自身类实例化
18         /// </summary>
19         public class Singleton2
20         {
21             private static Singleton2 instance;
22             private static readonly object syncRoot = new object();
23 
24             private Singleton2()
25             { }
26 
27             public static Singleton2 GetInstance()
28             {
29                 if (instance == null)
30                 {
31                     lock (syncRoot)//加锁
32                     {
33                         if (instance == null)
34                         {
35                             instance = new Singleton2();
36                         }
37                     }
38                 }
39 
40                 return instance;
41             }
42         }