参考了as2时代的GEventDispatcher类，改写成SSAS，并且精简了一下只提供3个最基本的功能

1. addEventListener( eventType:String , listener:object , listenerHandler:String )
2. removeEventListener(eventType:String , listener:object , listenerHandler:String )
3. dispatchEvent({type:"type"})

演示代码：
//需要用到的2个类
AAA = function(){}
BBB = function(){}

//首先加载EventDispatcher
load("N2EventDispatcher.asc")

application.onAppStart = function(){
 
  //a1是AAA类的一个实例
  var a1 = new AAA()
  //把a1变成广播者后，a1就可以广播事件了
  N2EventDispatcher.init(a1)
 
 
  //b1是BBB类的一个实例 ,他是一个监听者，监听a1广播的test事件
 var b1 = new BBB() //listener
 
 b1.onTest= function(eo /* :Event */){
   trace("收到"+eo.type +"事件")
  }
 
  a1.addEventListener("test",b1,"onTest") //参数为 (eventType , 监听者，监听者的handler)
  a1.dispatchEvent({type:"test"}) //广播事件，相当于 a1.dispatchEvent(new Event("test"))
 
  a1.removeEventListener("test",b1,"onTest") //删除监听
  a1.dispatchEvent({type:"test"}) //再广播就不会触发了
 
 
}

N2EventDispatcher 源代码：

try { var dummy = N2EventDispatcher; } catch ( e ) { // #ifndef N2VideoPlayback
 
 N2EventDispatcher = function(){}

 N2EventDispatcher.instance = undefined
 N2EventDispatcher.prototype._listeners = undefined
 

 N2EventDispatcher.prototype.init = function(p_obj)
 {
    if (N2EventDispatcher.instance == undefined)
    {
     N2EventDispatcher.instance = new N2EventDispatcher()
    }
    p_obj.dispatchEvent = N2EventDispatcher.instance.dispatchEvent;
    p_obj.addEventListener = N2EventDispatcher.instance.addEventListener;
    p_obj.removeEventListener = N2EventDispatcher.instance.removeEventListener;
   
  }
 
 N2EventDispatcher.prototype.addEventListener = function(p_eventType/* :String */,p_obj /*:Object*/,p_function/*String*/)
 {
    if (this._listeners == undefined)
    {
      this._listeners = {};
    }
    var listeners/* :Array */ = this._listeners[p_eventType];
    if (listeners == undefined)
    {
     this._listeners[p_eventType] = listeners = [];
    }
   
    if (N2EventDispatcher.indexOfListener(listeners,p_obj,p_function) == -1)
    {
      listeners.push({o:p_obj,f:p_function});
    }
  }
 
  N2EventDispatcher.prototype.removeEventListener = function (p_eventType /*:String*/,p_obj /*:Object*/,p_function /*:String*/) /*:Void*/
  {
    var listeners = this._listeners[p_eventType];
    if (listeners == undefined) { return; }
    var index /*:Number*/ = N2EventDispatcher.indexOfListener(listeners,p_obj,p_function);
    if (index != -1) { listeners.splice(index,1); }
  }
 
  N2EventDispatcher.prototype.dispatchEvent = function(p_eventObj)
  {
 if(this._listeners == undefined) return
    if (p_eventObj.target == undefined) { p_eventObj.target = this; }
    var arr = this._listeners[p_eventObj.type]
    if (arr != undefined)
    {
      for( i in arr){
        var scrope = arr[i].o
        var fun = arr[i].f
         scrope[fun](p_eventObj)
        }
    }
   
  }
 
  N2EventDispatcher.indexOfListener = function(p_listeners /*:Array*/ , p_obj/*:Object*/,p_function /*:String*/) /*:Number*/
 {
    var l /*:Number*/ = p_listeners.length;
    var i /*:Number*/ = -1;
    while (++i < l) {
      var obj /*:Object*/ = p_listeners[i];
      if (obj.o == p_obj && obj.f == p_function) { return i; }
    }
    return -1;
  }
 
 N2EventDispatcher.init = N2EventDispatcher.prototype.init

}