有没有从对象中删除未知事件侦听器的方法?

<mx:Button click="doCallback()" .../>

public var onClickFunction:Function = null;
private function doCallback():void
{
    if (onClickFunction != null)
    {
        onClickFunction(); // optionally you can pass some parameters in here if you match the signature of your callback
    }
}

包含按钮的控件的使用者将使用适当的函数设置onclick函数。事实上,你可以随心所欲地设置它。

addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void
dispatchEvent(event:Event):Boolean
hasEventListener(type:String):Boolean
removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void
willTrigger(type:String):Boolean 

如您所见,有两种方法可以告诉您某一类型的事件是注册了侦听器,还是其父级之一注册了侦听器,但这些方法实际上都不会返回已注册侦听器的列表。

现在,请去骚扰Adobe,因为它编写了这样一个无用的API。基本上,它们能让你知道“是否”事件流发生了变化,但是它们不能让你用这些信息做任何事情!

将侦听器存储为道具。添加另一个事件时,请检查侦听器是否存在,如果存在,请调用removeEventListener。

或者,重写按钮的addEventListener方法。调用addEventListener时,在字典对象中将闭包添加到事件之前将其存储。再次调用addEventListener时,请将其删除:

var listeners:Dictionary = new Dictionary();

override public function addEventListener( type : String, listener : Function, useCapture : Boolean = false, priority : int = 0, useWeakReference : Boolean = false) : void {

  if( listeners[ type ] ) {

     if( listeners[ type ] [ useCapture ] {

        //snip... etc: check for existence of the listener

        removeEventListener( type, listeners[ type ] [ useCapture ], useCapture );

        listeners[ type ] [ useCapture ] = null;

        //clean up: if no listeners of this type exist, remove the dictionary key for the type, etc...

     }

  }

  listeners[ type ] [ useCapture ] = listener;

  super.addEventListener( type, listener, useCapture, priority, useWeakReference );

};

为此,我编写了一个名为EventCurb的子类,请参见 blog

package
{
   import flash.events.EventDispatcher;
   import flash.utils.Dictionary;
   /**
    * ...
    * @author Thomas James Thorstensson
    * @version 1.0.1
    */
   public class EventCurb extends EventDispatcher
   {
      private static var instance:EventCurb= new EventCurb();
      private var objDict:Dictionary = new Dictionary(true);
      private var _listener:Function;
      private var objArr:Array;
      private var obj:Object;

      public function EventCurb() {
         if( instance ) throw new Error( "Singleton and can only be accessed through Singleton.getInstance()" );
      }

      public static function getInstance():EventCurb {
         return instance;
      }

      override public function addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void
      {
         super.addEventListener(type, listener, useCapture, priority, useWeakReference);
      }

      override public function removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void
      {
         super.removeEventListener(type, listener, useCapture);
      }

      public function addListener(o:EventDispatcher, type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void {
         // the object as key for an array of its event types
         if (objDict[o] == null)  objArr = objDict[o] = [];
         for (var i:int = 0; i <  objArr.length; i++) {
            if ( objArr[i].type == type)
            trace ("_______object already has this listener not adding!")
            return
         }
         obj = { type:type, listener:listener }
         objArr.push(obj);
         o.addEventListener(type, listener, useCapture, priority, useWeakReference);
      }

      public function removeListener(o:EventDispatcher, type:String, listener:Function, useCapture:Boolean = false):void {
         // if the object has listeners (ie exists in dictionary)
         if (objDict[o] as Array !== null) {
            var tmpArr:Array = [];
            tmpArr = objDict[o] as Array;
            for (var i:int = 0; i < tmpArr.length; i++) {
               if (tmpArr[i].type == type) objArr.splice(i);
            }

            o.removeEventListener(type, listener, useCapture);
            if (tmpArr.length == 0) {
               delete objDict[o]
            }
         }else {
            trace("_______object has no listeners");
         }
      }

      /**
       * If object has listeners, returns an Array which can be accessed
       * as array[index].type,array[index].listeners
       * @param   o
       * @return Array
       */
      public function getListeners(o:EventDispatcher):Array{
         if (objDict[o] as Array !== null) {
            var tmpArr:Array = [];
            tmpArr = objDict[o] as Array;
            // forget trying to trace out the function name we use the function literal...
            for (var i:int = 0; i < tmpArr.length; i++) {
               trace("_______object " + o + " has event types: " + tmpArr[i].type +" with listener: " + tmpArr[i].listener);
            }
            return tmpArr

         }else {
            trace("_______object has no listeners");
            return null
         }

      }

      public function removeAllListeners(o:EventDispatcher, cap:Boolean = false):void {
         if (objDict[o] as Array !== null) {
            var tmpArr:Array = [];
            tmpArr = objDict[o] as Array;
            for (var i:int = 0; i < tmpArr.length; i++) {
               o.removeEventListener(tmpArr[i].type, tmpArr[i].listener, cap);
            }
            for (var p:int = 0; p < tmpArr.length; p++) {
               objArr.splice(p);
            }

            if (tmpArr.length == 0) {
               delete objDict[o]
            }
         }else {
            trace("_______object has no listeners");
         }
      }
   }
}

我喜欢做的事情是使用一个动态全局类,并在内联中添加对侦听器函数的快速引用。这意味着您希望像我一样在addEventListener方法中拥有listener函数。这样,您可以在addEventListener中使用removeEventListener:)

试试这个:

package {

import flash.display.Sprite;
import flash.events.Event;
import flash.text.TextField;

[SWF(width="750", height="400", backgroundColor="0xcdcdcd")]
public class TestProject extends Sprite
{   
    public function TestProject()
    {
        addEventListener(Event.ADDED_TO_STAGE, Global['addStageEvent'] = function():void {
            var i:uint = 0;
            //How about an eventlistener inside an eventListener?
            addEventListener(Event.ENTER_FRAME, Global['someEvent'] = function():void {
                //Let's make some text fields
                var t:TextField = new TextField();
                    t.text = String(i);
                    t.x = stage.stageWidth*Math.random();
                    t.y = stage.stageHeight*Math.random();
                addChild(t);
                i++;
                trace(i);
                //How many text fields to we want?
                if(i >= 50) {
                    //Time to stop making textFields
                    removeEventListener(Event.ENTER_FRAME, Global['someEvent']);
                    //make sure we don't have any event listeners
                    trace("hasEventListener(Event.ENTER_FRAME) = "+hasEventListener(Event.ENTER_FRAME));    
                }
            });

            //Get rid of the listener
            removeEventListener(Event.ADDED_TO_STAGE, Global['addStageEvent']);
            trace('hasEventListener(Event.ADDED_TO_STAGE) = '+hasEventListener(Event.ADDED_TO_STAGE));

        });
    }

}   

动态类全局{}

秘密是动态类全局。使用它,您可以在运行时动态添加属性。

mouseEnabled=在事件目标上为false。

http://www.thoughtprocessinteractive.com/blog/the-power-and-genius-of-mousechildren-and-mouseenabled

K2xL事件管理器类 http://k2xl.com/wordpress/2008/07/02/as3-eventmanager-class-removealllisteners/

private function callFunction(function:Function):void
{
     checkObject();
     obj.addEventListener(MouseEvent.CLICK,function);
}

private function checkObject():void
{
    if(obj.hasEventListener(MouseEvent.CLICK))
   {
      //here remove that objects
   }
}