Flex 框架PureMVC 源码解析之--View篇
/* PureMVC - Copyright(c) 2006-08 Futurescale, Inc., Some rights reserved. Your reuse is governed by the Creative Commons Attribution 3.0 United States License*/package org.puremvc.as3.core{import org.puremvc.as3.interfaces.*;import org.puremvc.as3.patterns.observer.Observer;// 中介名称-中介 列表protected var mediatorMap : Array;// 消息名称-观察者列表protected var observerMap: Array;// 单例的viewprotected static var instance: IView;// 出错消息protected const SINGLETON_MSG: String = "View Singleton already constructed!";public class View implements IView{/** * 构造函数，并构造相应的map * * * @throws Error * */public function View( ){if (instance != null) throw Error(SINGLETON_MSG);instance = this;mediatorMap = new Array();observerMap = new Array();initializeView();}/** * 初始化view，由构造函数自动调用， * 在子类中可以通过此函数初始化view而不用覆盖构造函数 * * @return void */protected function initializeView( ) : void {}/** * 单例view的工厂方法 * * @return 返回单例view */public static function getInstance() : IView {if ( instance == null ) instance = new View( );return instance;}/** * 作用：注册观察者 * //对一个消息可能存在多个观察者 * @param notificationName 消息名称 * @param observer 要注册的观察者 */public function registerObserver ( notificationName:String, observer:IObserver ) : void{//得到该消息对应的所有观察者，如果不为空，就把这个观察者加进去，如若为空就初始化var observers:Array = observerMap[ notificationName ];if( observers ) {observers.push( observer );} else {observerMap[ notificationName ] = [ observer ];}}/** * * 作用：通知所有的观察者了 * * * @param notification 要通知观察者的消息 */public function notifyObservers( notification:INotification ) : void{if( observerMap[ notification.getName() ] != null ) {//获取该消息的所有对应观察者var observers_ref:Array = observerMap[ notification.getName() ] as Array;//这有点迷糊完全可以这样写,原因是因为在循环的时候observers可能发生变化/** * *for(var i:Number = 0;i<observers_ref.length;i++) *{ *observer = observers_ref[i] as IObserver; *observer.notifyObserver(notification); *} * * * */ var observers:Array = new Array(); var observer:IObserver;for (var i:Number = 0; i < observers_ref.length; i++) { observer = observers_ref[ i ] as IObserver;observers.push( observer );}// Notify Observers from the working arrayfor (i = 0; i < observers.length; i++) {observer = observers[ i ] as IObserver;observer.notifyObserver( notification );}}}/** * 作用：根据给定的消息名和对消息感兴趣的对象移除观察者 * //上面提到一个消息名称可能对于多个观察者，所以必须使用第二个参数进一步确定 * @param notificationName 消息名称 * @param notifyContext 对消息感兴趣的对象 */public function removeObserver( notificationName:String, notifyContext:Object ):void{// the observer list for the notification under inspectionvar observers:Array = observerMap[ notificationName ] as Array;// find the observer for the notifyContextfor ( var i:int=0; i<observers.length; i++ ) {if ( Observer(observers[i]).compareNotifyContext( notifyContext ) == true ) {observers.splice(i,1);break;}}if ( observers.length == 0 ) {delete observerMap[ notificationName ];}} /** * 作用：注册中介 * @param mediator 要注册的中介实例 */public function registerMediator( mediator:IMediator ) : void{//保证以中介名称为key的对象在mediatorMap中唯一if ( mediatorMap[ mediator.getMediatorName() ] != null ) return;// 根据名称注册该MediatormediatorMap[ mediator.getMediatorName() ] = mediator;// 得到所以该Mediator感兴趣的消息var interests:Array = mediator.listNotificationInterests();// 其实说白了是把Mediator感兴趣的消息都注册成观察者，以便得到通知if ( interests.length > 0 ) {var observer:Observer = new Observer( mediator.handleNotification, mediator );for ( var i:Number=0; i<interests.length; i++ ) {registerObserver( interests[i], observer );}}mediator.onRegister();}/** * 作用：根据中介名称获取中介 * * @param mediatorName 要获取中介名称 * @return */public function retrieveMediator( mediatorName:String ) : IMediator{return mediatorMap[ mediatorName ];}/** * 作用：从view中移除中介 * * @param mediatorName 要移除的中介名称 * @return */public function removeMediator( mediatorName:String ) : IMediator{// 先拿到该中介var mediator:IMediator = mediatorMap[ mediatorName ] as IMediator;if ( mediator ) {// 根据感兴趣的消息移除观察者var interests:Array = mediator.listNotificationInterests();for ( var i:Number=0; i<interests.length; i++ ) {removeObserver( interests[i], mediator );}// 移除中介delete mediatorMap[ mediatorName ];// alert the mediator that it has been removedmediator.onRemove();}return mediator;}/** * 作用：根据名称判断是否存在该中介 * * @param mediatorName 中介名称 * @return */public function hasMediator( mediatorName:String ) : Boolean{return mediatorMap[ mediatorName ] != null;}}}?