C#设计模式——单例模式



单例模式：单例模式确保某一个类只有一个实例，而且自行实例化并向整个系统提供这个实例。构造函数私有表示子类不能继承

publicclass Singleton

    {

        private static Singleton m_instance =null;

 

        private Singleton()

        {

        }

        public static Singleton getInstance()

        {

             if(m_instance==null)

             {

                  m_instance=new Singleton();

             }

             return m_instance;

        }

    }

多例模式：多例模式，实际上就是单例模式的自然推广，单例类一般情况下只可以有一个实例，但单例类也可以推广到允许有限个实例。多例类分为有上限多例类与无上限多例类。

publicclass Multiton

    {

        private static Multiton instance1=null;

        private static Multiton instance2=null;

 

        private Multiton()

        {

         }

 

        public static Multiton getInstance(int whichOne)

        {

             if(whichOne==1)

             {

                  if(instance1==null)

                  {

                      instance1=new Multiton ();

                  }

                  return instance1;

             }

             else

             {

                  if(instance2==null)

                  {

                      instance2=new Multiton ();

                  }

              return instance2;

 

             }

        }

    }