Mediator作为这套MVC框架的核心部分承载了大部分的功能。Mediator主要分三类：DirectorMediator,SceneMediator,LayerMediator。这三类Mediator都是继承自IMediator，IMediator的实现如下：
/***The game.IMediator
@author ituuz
@date 2014-11-18
IView is the mediator of MVC,create your model to extend this class. In this mediator can get model,current mediator and rootMediator.
*/ game.IMediator = cc.Class.extend({
ctor:function () { },
show:function () {
throw new Error("SubClass not overwrite show function.");
},
getCurrMediator:function () {
var med = game.Facade._directorMediator.currSceneMediator.currLayerMediator;
if (med == null) {
med = game.Facade._directorMediator.currSceneMediator.rootLayerMediator;
}
return med;
},
getRootMediator:function () {
return game.Facade._directorMediator.currSceneMediator.rootLayerMediator;
},
getModel:function (cls) {
return game.Facade._modelMap.get(cls);
},
//Use this function to send notification.
send:function (key,obj) {
game.Notification.send(key,obj);
} });
show函数需要它的子类去实现，show的主要作用就是该Mediator被创建时显示的内容。send函数是用来发送消息的。除此之外还有三个get函数，分别是获取当前Mediator、获取RootMediator和获取Model对象。
下面单独介绍继承自Mediator的这三类Mediator的作用。
首先是DirecotorMediator，它主要是来控制场景的创建和销毁。代码实现如下：
/*
The DirectorMediator
18
Control the scene show or hide.
*/ game.DirectorMediator = game.IMediator.extend({
sceneMediatorStack:null,
currSceneMediator:null,
ctor:function (view) {
this.currView = view;
this.sceneMediatorStack = new game.Stack();
},
show:function (parent) { },38)">//Open the new scene and destroy the prevIoUs.
showScene:function (mediator) {
if (this.currSceneMediator
&& this.currSceneMediator.rootLayerMediator) {
this.currSceneMediator.rootLayerMediator._pDispose();
}
if (this.currSceneMediator) {
var layMedList = this.currSceneMediator.layerMediatorList; while (layMedList.size() > 0) {
var med = layMedList.pop();
med._pDispose();
}
}
this.currSceneMediator = mediator;
this.sceneMediatorStack = new game.Stack();
this.sceneMediatorStack.push(mediator);
cc.director.runScene(mediator.currScene);
},38)">//Open the new scene and push the prevIoUs into the stack
pushScene:function (mediator) {
this.currSceneMediator = mediator;
this.sceneMediatorStack.push(mediator);
cc.director.pushScene(mediator.currScene);
},38)">//Pop the current scene to destroy then go to the prevIoUs scene.
popScene:function () {
var pop = this.sceneMediatorStack.pop();
var curr = this.sceneMediatorStack.top();
this.currSceneMediator = curr;
cc.director.popScene();
} });
DirectorMediator除了继承了Mediator的几个函数外，还有几个控制Scene打开和关闭的函数，分别是showScene,pushScene,popScene，都是控制场景打开和关闭的。
然后介绍的是SceneMediator，它主要是控制LayerMediator的生命周期。控制着LayerMediator的创建和销毁。实现如下：
/*The SceneMediator
18
Control the layer show or hide.
*/ game.SceneMediator = game.IMediator.extend({
currScene:null,
currLayerMediator:null,
rootLayerMediator:null,
layerMediatorList:null,
ctor:function (view) {
this.currScene = view;
this.layerMediatorList = new game.Stack();
},
show:function (obj) {
if (this.currLayerMediator == undefined
|| this.currLayerMediator == null ) {
this.rootLayerMediator.init();
this.rootLayerMediator.show(this.currScene,obj);
} else {
this.currLayerMediator.init();
this.currLayerMediator.isRoot = false;
this.currLayerMediator.show(this.currScene,obj);
}
},38)">//Setting the root layer
rootLayer:function (layerMed) {
this.rootLayerMediator = layerMed;
},
showRoot:function () {
this.show();
},38)">//Open the new layer and destroy prevIoUs layer.
showLayer:function (layerMed,obj) {
this.currLayerMediator = layerMed;
this.layerMediatorList = new game.Stack();
this.layerMediatorList.push(layerMed);
this.show(obj);
},38)">//Open the new layer and push the prevIoUs layer into stack.
pushLayer:function (layerMed,obj) {
this.currLayerMediator = layerMed;
this.layerMediatorList.push(layerMed);
this.show(obj);
},
//Pop the current layer to destroy then go to the prevIoUs layer.
popLayer:function (obj) {
var layer = this.layerMediatorList.pop();
layer && layer._pDispose();
this.currLayerMediator = this.layerMediatorList.top();
if (this.currLayerMediator) {
this.currLayerMediator.freshen(obj);
} else {
this.rootLayerMediator.freshen(obj);
}
} });
它同DirectorMediator一样，控制着LayerMediator，并且拥有几个控制它的函数，包括showLayer、pushLayer、popLayer，除此之外他还有个rootLayer和showRoot函数，这两个函数是用来设置和显示场景上的初始Layer的，cocos2dx中场景内必须有Layer才能显示内容，所以这两个函数设置并显示了root layer。同时SceneMediator还重写了show函数，在重写的show函数中初始化了LayerMediator并且调用了LayerMediator的show函数用来显示Layer。
最后我们介绍一下LayerMediator，这个Mediator我们使用的频率最高，同时包含的功能也比较多。先来看代码：
/************************************************************************** The LayerMediator
@author ituuz
@date 2014-11-18 The layer's logic. *************************************************************************/
game.LayerMediator = game.IMediator.extend({
currView:null,
backBtn:null,
mask:null,
isRoot:true,
ctor:function (view) {
this.currView = view;
},
show:function (parent,obj) {
if (this.isRoot) return;
var size = cc.winSize;
this.mask = new cc.LayerColor(cc.color(0,200),size.width,size.height);
parent.addChild(this.mask);
cc.eventManager.addListener({
event: cc.EventListener.TOUCH_ONE_BY_ONE,
swallowTouches: true,
onTouchBegan: this.onTouchBegan
},this.mask);
},
onTouchBegan:function(touch,event) {
//Could to do sth.
return true;
},
init:function () {
throw new Error("SubClass must be overwrite init function and regist event in this function.");
},
freshen:function (obj) {
cc.log("freshen");
},
//Use this function to send notification.
send:function (key,obj) {
game.Notification.send(key,obj);
},
subscrib:function (type,callback,target) {
game.Notification.subscrib(type,target);
},
unsubscrib:function (type,callback) {
game.Notification.unsubscrib(type,callback);
},136); font-style:italic">//Switch scene
showScene:function (sceneMed) {
game.Facade._directorMediator.showScene(sceneMed);
game.Facade._directorMediator.currSceneMediator.showRoot();
},136); font-style:italic">//Push new scen into the stack
pushScene:function (sceneMed) {
game.Facade._directorMediator.pushScene(sceneMed);
game.Facade._directorMediator.currSceneMediator.showRoot();
},136); font-style:italic">//Pop current scene out of the stack
popScene:function () {
game.Facade._directorMediator.popScene();
},136); font-style:italic">//Switch layer
showLayer:function (layerMed,obj) {
game.Facade._directorMediator.currSceneMediator.showLayer(layerMed,obj);
},136); font-style:italic">//Push new layer into the stack
pushLayer:function (layerMed,obj) {
game.Facade._directorMediator.currSceneMediator.pushLayer(layerMed,
//Pop current scene out of the stack
popLayer:function (obj) {
game.Facade._directorMediator.currSceneMediator.popLayer(obj);
},136); font-style:italic">//private
_pDispose:function () {
var that = this;
that.destroy();
that.currView.removeFromParent(true);
that.mask && this.mask.removeFromParent(true);
},
destroy:function () {
throw new Error("SubClass must be overwrite destroy function and delete event in this function.");
} });
这里面通用的几个pop、show、push函数就不多说了，主要说一下其他特殊的函数。首先是构造函数，它有一个参数view，这个view就是和这个Mediator对应的Layer，这里保存了个引用，方便使用。然后是重写的show函数，在该函数中的两个参数parent是该layer的父级容器，obj是在打开该Layer时传入的参数。在show里还对打开的Layer进行了模态处理。还有init函数，该函数是在该LayerMediator初始化时调用的，可以在该函数中初始化一些数据，或者注册监听等。然后LayerMediator中还提供了几个消息相关的函数，分别是发送消息send、注册消息subscrib、删除消息注册unsubscrib。还有freshen(obj)函数是在上层Layer关闭时调用的，obj是可以传递的值，在该函数中可以做一些UI刷新的功能。最后比较重要的两个函数都是有关销毁的。destroy函数是必须在子类重写的，在LayerMediator被销毁时调用，_pDispose是私有的函数，负责销毁公有的对象，不能显示调用。
Mediator在MVC中比较重要，除了自身的动能外，还承载了其他几个功能。首先Mediator中持有View对象，可以对View进行显示更新，同时也要响应View上的各种事件。然后Mediator可以注册和发送消息。同时Mediator还可以获取Model对象，进行操作。
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