单例模式(Singleton Pattern)

介绍
保证一个类仅有一个实例,并提供一个访问它的全局访问点。

1.jpg.png
示例
保证一个类仅有一个实例。



Singleton

http://www.cnblogs.com/Images/OutliningIndicators/None.gifusing System;
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
using System.Collections.Generic;
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
using System.Text;
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
namespace Pattern.Singleton
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif{
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif    
/// <summary>
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif    
/// 泛型实现单例模式
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif    
/// </summary>
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif    
/// <typeparam name="T">需要实现单例的类</typeparam>
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif    
public class Singleton<T> where T : new()
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif    {
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif        
/// <summary>
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif        
/// 返回类的实例
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif        
/// </summary>
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif        
public static T Instance
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif        {
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif            
get { return SingletonCreator.instance; }
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif        }
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif        
class SingletonCreator
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif        {
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif            
internal static readonly T instance = new T();
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif        }
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif    }
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif}
http://www.cnblogs.com/Images/OutliningIndicators/None.gif



Test

http://www.cnblogs.com/Images/OutliningIndicators/None.gifusing System;
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
using System.Data;
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
using System.Configuration;
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
using System.Collections;
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
using System.Web;
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
using System.Web.Security;
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
using System.Web.UI;
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
using System.Web.UI.WebControls;
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
using System.Web.UI.WebControls.WebParts;
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
using System.Web.UI.HtmlControls;
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
using Pattern.Singleton;
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
public partial class Singleton : System.Web.UI.Page
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif{
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif    
protected void Page_Load(object sender, EventArgs e)
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif    {
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif        
// 使用单例模式,保证一个类仅有一个实例
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif
        Response.Write(Singleton<Test>.Instance.Time);
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif        Response.Write("<br />");
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif        Response.Write(Singleton<Test>.Instance.Time);
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif        Response.Write("<br />");
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif        
// 不用单例模式
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif
        Test t = new Test();
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif        Response.Write(t.Time);
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif        Response.Write("<br />");
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif        Test t2 = 
new Test();
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif        Response.Write(t2.Time);
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif        Response.Write("<br />");
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif    }
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif}
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
http://www.cnblogs.com/Images/OutliningIndicators/None.gif
public class Test
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif{
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif    
private DateTime _time;
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif    
public Test()
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif    {
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif        System.Threading.Thread.Sleep(3000);
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif        _time = DateTime.Now;    
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif    }
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif
http://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif    
public string Time
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif    {
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif        
get { return _time.ToString(); }
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif    }
http://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif}
http://www.cnblogs.com/Images/OutliningIndicators/None.gif


运行结果
2007-2-10 22:35:11
2007-2-10 22:35:11
2007-2-10 22:35:14
2007-2-10 22:35:17