as3中创建对象池

创建对象池的代码如下：

	import flash.display.DisplayObject;

	public class SpritePool 
	{
		private var pool:Array;
		private var counter:int;
		public function SpritePool(type:Class,len:int) 
		{
			pool = new Array();
			counter = len;
			
			var i:int = len;
			while (--i > -1)
			{
				pool[i] = new type();
			}
		}
		
		public function getSprite():DisplayObject
		{
			if (counter > 0)
			{
				return pool[--counter];
			}
			else 
			{
				throw new Error("You exhausted the pool!");
			}
		}
		
		public function returnSprite(s:DisplayObject):void
		{
			pool[counter++] = s;
		}
		
	}

如何使用
private var pool:SpritePool;
初始化 pool = new SpritePool(Bullet,10); //Bullet是一个子弹类
取出一个对象
var b:Bullet = pool.getSprite() as Bullet;
移除一个对象时
var b:Bullet = bullets[i];
pool.returnSprite(b);