AS3单例模式

【方法一】

package
{
  public class Singleton
  {
   private static var _singletonModeMark:Boolean;
   private static var _instence:ScoreController;
   public static function getSingleton():Singleton
   {
     if (!_instence)
        {
          _singletonModeMark = true;
          _instence = new ScoreController;
          _singletonModeMark = false;
         }
    }
   public function Singleton():void
    {
       if (!_singletonModeMark)
         {
           throw new Error("只能通过静态方法getSingleton()来得到Singleton类的单例");
          }
      }
   }        
}

【方法二】

package com.peachpit.aas3wdp.singletonexample {

   public class Singleton {

      static private var _instance:Singleton;

      public function Singleton(singletonEnforcer:SingletonEnforcer) {}

      public static function getInstance():Singleton {
         if(Singleton._instance == null) {
            Singleton._instance = new Singleton(new SingletonEnforcer());
         }
         return Singleton._instance;
      }

      public function doSomething():void {
         trace("SOMETHING!");
      }
   }

}

class SingletonEnforcer {}