using System; 
using System.Collections.Generic; 
using System.Text; 
 
namespace Pattern.Singleton 
{ 
         /// <summary> 
         /// 泛型实现单例模式 
         /// </summary> 
         /// <typeparam name="T">需要实现单例的类</typeparam> 
         public  class Singleton<T> where T :  new() 
        { 
                 /// <summary> 
                 /// 返回类的实例 
                 /// </summary> 
                 public  static T Instance 
                { 
                        get {  return SingletonCreator.instance; } 
                } 
 
                 class SingletonCreator 
                { 
                         internal  static  readonly T instance =  new T(); 
                } 
        } 
}

using System; 
using System.Data; 
using System.Configuration; 
using System.Collections; 
using System.Web; 
using System.Web.Security; 
using System.Web.UI; 
using System.Web.UI.WebControls; 
using System.Web.UI.WebControls.WebParts; 
using System.Web.UI.HtmlControls; 
 
using Pattern.Singleton; 
 
public partial  class Singleton : System.Web.UI.Page 
{ 
         protected  void Page_Load( object sender, EventArgs e) 
        { 
                 // 使用单例模式，保证一个类仅有一个实例 
                Response.Write(Singleton<Test>.Instance.Time); 
                Response.Write( "<br />"); 
                Response.Write(Singleton<Test>.Instance.Time); 
                Response.Write( "<br />"); 
 
                 // 不用单例模式 
                Test t =  new Test(); 
                Response.Write(t.Time); 
                Response.Write( "<br />"); 
                Test t2 =  new Test(); 
                Response.Write(t2.Time); 
                Response.Write( "<br />"); 
        } 
} 
 
public  class Test 
{ 
         private DateTime _time; 
 
         public Test() 
        { 
                System.Threading.Thread.Sleep(3000); 
                _time = DateTime.Now;         
        } 
 
         public  string Time 
        { 
                get {  return _time.ToString(); } 
        } 
}

     本文转自webabcd 51CTO博客，原文链接：http://blog.51cto.com/webabcd/344515，如需转载请自行联系原作者