ActionScript 3.0 事件机制小结
这次先把ActionScript 3.0 事件机制总结一下先吧，这里只说一下自定义类发送事件的3中方式，因为在设计模式中是比较常用的。例如MVC。
关于自定义事件，主要由于两个类：事件类（Event）,事件发送类（EventDispatcher）。我们讨论的自定义发送事件，就是如何使对象能够发送事件。
方式一：继承EventDispatcher类
package
{
import flash.display.Sprite;
import flash.events.Event;
import flash.events.EventDispatcher;
/**
* ...
* @author 橡树小屋
*/
public class estends extends Sprite
{
function estends() {
//第一种
var dispatcher:extendsDispatcher = new extendsDispatcher();
dispatcher.addEventListener(extendsDispatcher.ACTION, actionH);
dispatcher.doSome();
//第二种
var dispatcher1:EventDispatcher = new EventDispatcher();
dispatcher1.addEventListener("secDispatcher", actionH);
dispatcher1.dispatchEvent(new Event("secDispatcher"));
//或者
dispatcher.addEventListener("thurdDispatcher", actionH);
dispatcher.dispatchEvent(new Event("thurdDispatcher"));
}
private function actionH(e:Event):void {
trace(e);
}
}
}
import flash.events.Event;
import flash.events.EventDispatcher;
class extendsDispatcher extends EventDispatcher {
public static var ACTION:String = "action";
public function doSome():void {
dispatchEvent(new Event(extendsDispatcher.ACTION));
}
}
只要继承EventDispatcher类，就可以直接用EventDispatcher类的方法发送事件，方便简单。
方式二：复合EventDispatcher对象
package
{
/**
* ...
* @author 橡树小屋
*/
import flash.display.Sprite;
import flash.events.Event;
public class compont extends Sprite
{
public function compont() {
var dis:compont1 = new compont1();
dis.getEventDispatch().addEventListener(compont1.ACTION, show);
dis.doSome();
}
private function show(e:Event):void {
trace(e);
}
}
}
import flash.events.Event;
import flash.events.EventDispatcher;
class compont1 {
private var _dispatcher:EventDispatcher;
public static var ACTION:String = "action";
public function compont1() {
_dispatcher = new EventDispatcher();
}
public function getEventDispatch():EventDispatcher {
return _dispatcher;
}
public function doSome():void {
_dispatcher.dispatchEvent(new Event(compont1.ACTION));
}
}
所谓的复合，其实就是用EventDispatcher发送事件而已，因为EventDispatcher本身就是个事件发送类，一般情况下，用EventDispatcher发送事件反而会更简单。
方式三：实现IEventDispatcher接口
package
{
import flash.display.Sprite;
import flash.events.Event;
/**
* ...
* @author 橡树小屋
*/
public class implement extends Sprite
{
public function implement() {
var impObj:implete = new implete();
impObj.addEventListener(implete.ACTION, actionH);
impObj.dispatchEvent(new Event(implete.ACTION));
}
private function actionH(e:Event):void {
trace(e);
}
}
}
import flash.events.Event;
import flash.events.EventDispatcher;
import flash.events.IEventDispatcher;
class implete implements IEventDispatcher {
public var _dispatcher:EventDispatcher;
public static const ACTION:String = "action";
public function implete() {
_dispatcher = new EventDispatcher();
}
//实现5个方法
public function addEventListener(type:String,listener:Function,useCapture:Boolean=false,priority:int=0,useWeakReference:Boolean=true):void {
_dispatcher.addEventListener(type, listener, useCapture, priority, useWeakReference);
}
public function dispatchEvent(evt:Event):Boolean {
return _dispatcher.dispatchEvent(evt);
}
public function hasEventListener(type:String):Boolean {
return _dispatcher.hasEventListener(type);
}
public function removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void {
_dispatcher.removeEventListener(type,listener,useCapture);
}
public function willTrigger(type:String):Boolean {
return _dispatcher.willTrigger(type);
}
}
当类本身要继承其他类，无法继承EventDispatcher类的时候，同时又希望这个类能够成为一个单纯的事件发送类，并且可以自己添加某些方法在里面，这时候用继承IEventDispatcher接口就比较合适了，不过过程比较麻烦写，要实现IEventDispatcher接口的5个方法。
参考资料：
《flash ActionScript 3.0 殿堂之路》