单件模式

using System;
using System.Collections.Generic;

/// <summary>
/// 单件模式(线程安全的单件(双重锁定方法2:线程安全而且性能优越))
/// </summary>
public class Singleton
{
    /// <summary>
    /// 定义自身静态变量实例默认为null
    /// </summary>
    private static Singleton instance=null;
    
    private static readonly object olock=new Object();
    ///私有构造函数
    /// 之所以不为public类型,因为是为了避免发生new Singleton()产生实例
    private Singleton()
    {}
    public static Singleton getInstance()
    {
        if(instance==null)
        {
            lock(olock)
            {
                if(instance==null)
                {
                    instance=new Singleton();
                }
                return instance;
            }
        }
    }
}

 1         public static Singleton GetInstance()
 2         {
 3             if (singleton == null)
 4             {
 5                 lock (syncObject)
 6                 {
 7 
 8                     if (singleton == null)
 9                     {
10                         singleton = new Singleton();
11                     }
12                 }
13             }
14             return singleton;
15         } 

 1 namespace Singleton
 2 {
 3     public sealed class Singleton
 4     {
 5         private static readonly Singleton singleton = new Singleton();
 6 
 7         private Singleton()
 8         {
 9         }
10 
11         public static Singleton GetInstance()
12         {
13             return singleton;
14         }
15     }
16 }