观察者模式

1.继承AsEventDispatcher类可以发送事件，添加事件侦听

package
{
	import flash.events.Event;
	import flash.utils.Dictionary;

	public class AsEventDispatcher
	{
		//[事件类型]=事件处理函数
		private var receive:Dictionary = new Dictionary();
		
		public function AsEventDispatcher()
		{
		}
		//添加接收者
		public function addEventListener(type:String, listener:Function):void
		{
			receive[type] = listener;
		}
		//清除接收者
		public function removeEventListener(type:String, listener:Function):void
		{
			trace("removeEventListener");
			for(var _type:String in receive)
			{
				if(_type == type &&receive[_type] == listener)
				{
					delete receive[_type];
				}
			}
		}
		//发送事件
		public function dispatchEvent(evt:AsEvent):void
		{
			for(var _type:String in receive)
			{
				if(_type == evt.type)
				{
					receive[evt.type](evt);
				}
			}
		}
	}
}

2. 通过dispatchEvent发出的事件都要是AsEvent，或者AsEvent的子类

package
{
	public class AsEvent
	{
		private var _type:String;
		public function AsEvent(_typeStr:String)
		{
			_type = _typeStr;
		}
		public function get type():String
		{
			return _type;
		}
	}
}

3.运行

package
{
	public class cs extends AsEventDispatcher
	{
		public function cs()
		{
			this.addEventListener("Event", onEvent);
			//this.removeEventListener("Event", onEvent);
			this.dispatchEvent(new AsEvent("Event"));
		}
		private function onEvent(evt:AsEvent):void
		{
			trace("..."); //输出...
		}
	}
}