分享一个单例模型类 Singleton

每个对象都写单例，单调又无聊。因此我写了个基类，只要集成，就实现了单例。

而且支持多单例（不同id对应不同的单例）

using  System;
using  System.Collections.Generic;
using  System.Text;

namespace  Pixysoft.DesignPattern
{
     public   class  Singleton < T >
    {
         private  Dictionary < string , T >  dict  =   new  Dictionary < string , T > ();

         private   string  _id  =   null ;

         private   static   volatile   object  instance;

         private   static   object  syncRoot  =   new  Object();

         public   static  T Instance
        {
             get
            {
                 if  (instance  ==   null )
                {
                     lock  (syncRoot)
                    {
                        instance  =  Activator.CreateInstance( typeof (T));
                    }
                }

                 return  (T)instance;

            }
        }

         public  T  this [ string  id]
        {
             get
            {
                 // 如果是null，表示自己，则直接返回Instance

                 if  ( string .IsNullOrEmpty(id))
                     return  Instance;

                id  =  id.Trim().ToUpper();

                 lock  (syncRoot)
                {
                     if  (dict.ContainsKey(id))
                         return  dict[id];

                     object  i  =  Activator.CreateInstance( typeof (T));

                    ((Singleton < T > )i)._id  =  id;

                    T it  =  (T)i;

                    dict.Add(id, it);

                     return  it;
                }
            }
        }

         public  T  this [ int  index]
        {
             get
            {
                 if  (index  <   0   ||  index  >  dict.Keys.Count  -   1 )
                     return  Instance;

                 int  coutner  =   0 ;

                 foreach  ( string  key  in  dict.Keys)
                {
                     if  (coutner  >=  index)
                         return  dict[key];

                    coutner ++ ;
                }

                 return  Instance;

            }
        }

         public   string  SingletonId
        {
             get  {  return  _id; }
        }
    }
}

使用方法：

     class  testclass
    {
         private   void  test()
        {
            Hello.Instance.Test();

            Hello.Instance[ " id " ].Test();
        }
    }

     public   class  Hello : Singleton < Hello >
    {

         public   void  Test()
        {
            Console.Write( " hello " );
        }
    }

看看有什么错误等，希望能够指出。谢谢！

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