Flex的Array和ArrayCollection总结
1.array作为控件使用?
?? FLEX3写法：?
????? <mx:Array id="barname">?
????????? <mx:String>Flash</mx:String>?
????????? <mx:String>Director</mx:String>?
????????? <mx:String>Dreamweaver</mx:String>?
????????? <mx:String>ColdFusion</mx:String>?
????? </mx:Array>?
?? FLEX4写法：?
????? <fx:Array id="barname">?
????????? <fx:String>Flex</fx:String>?
????????? <fx:String>Flash</fx:String>?
????????? <fx:String>Dreamweaver</fx:String>?
????? </fx:Array>?
?? 举例?
?? <mx:LinkBar? id="navigationBar" dataProvider="{barname}"/>?
?? <mx:LinkBar? id="navigationBar" dataProvider="barname"/>?
?? 注：写{}，则当barname数据的值修改后，linkbar的数据同步更新?
2.array在程序中使用?
?? [Bindable]?
?? public var barname:Array=["Flex","Flash","Dreamweaver"];?
?? <mx:LinkBar? id="navigationBar" dataProvider="{barname}"/>?
?? var barname:Array = new Array();?
?? barname.push("Flex");?
?? barname.push("Flash");?
?? barname.push("Dreamweaver");?
?? navigationBar.dataProvider = barname;?
3.array的排序?
?? private var temp:Array = new Array(1,4,3,45,4,6,7,77,9);??
?? function sortArray(numbers:Array):Array{????????
????? numbers.sort(Array.NUMERIC);??
????? return numbers;??
?? }?
4.ArrayCollection特点?
?? ArrayCollection是flex中的数组集合类，它是很常用的，我们使用它时需要注意几个地方?
(1)事件监听?
??? ArrayCollection可以为它注册一个集合改变的监听事件(CollectionEvent.COLLECTION_CHANGE)，就是一旦 ArrayCollection数组改变就会触发Event，不是所有情况的改变都会触发改变事件，如果集合当中的对象属性没有被绑定，那么你改变它的对象值也是不会触发事件的，在这种情况下你也许可能需要去将对象的属性进行绑定或者通过itemUpdated方法去管理对象值改变,除非集合的长度改变了,事件才会被触发?
(2)对象删除?
??? ArrayCollection的对象删除方法removeAll()，有这样一种情况，当你在过滤集合数据的时候，它并不会删除所有数据，而是删除全部过滤的数据，不符合过滤条件的数据就没被删除，依然还在source中?
(3)过滤函数?
??? ArrayCollection有个filterFunction过滤函数，就是可能集合中你只需要显示其中某几个对象，你将会需要根据对象条件筛选对象，那么你可能会用过滤函数，过滤函数会将不符合条件的对象过滤出来，但是ArrayCollection有个source属性是不会变的，它是个数组，所有源数据全在里面，尽管你去过滤，所有对象都会一直存在其中?
(4)排序?
??? ArrayCollection还有一个sort属性是用来排序的，你可以为其指定排序字段?
5.ArrayCollection在程序中使用?
(1)插入或删除?
?? import mx.collections.ArrayCollection;??
?? private var coll:ArrayCollection;??
??? coll = new ArrayCollection(??
?????????? [{name:"Martin Foo", age:25},??
??????????? {name:"Joe Bar", age:15},??
??????????? {name:"John Baz", age:23}]);??
??? }?
?? 要插入元素，可使用addItemAt和addItem：??
?? coll.addItemAt({name:"James Fez", age:40}, 0);?
?? coll.addItem({name:"James Fez", age:40});?
(2)搜索?
?? Sort 对象提供findItem 方法用于搜索这个ArrayCollection 中的所有元素。?
方法原型如下：?
?? public function findItem(items:Array, values:Object, mode:String,?
returnInsertionIndex:Boolean = false, compareFunction:Function = null):int?
?? Value 参数可以是包含属性和所需值的任何对象。?
?? Mode 字符串可以是Sort.ANY_INDEX_MODE，表示返回任何匹配项索引，Sort.FIRST_INDEX_MODE 表示返回第一个匹配项索引，Sort.LAST_INDEX_MODE 表示返回最后一个匹配项索引。?
?? returnInsertionIndex 参数表示如果该方法找不到由values 参数标识的项目，并且此参数为?
true，则findItem() 方法将返回这些值的插入点，也就是排序顺序中应插入此项目的。?
?? compareFunction 设置用于查找该项目的比较运算符函数.?
举例?
?? private function checkExistence():int {???
????? var sort:Sort = new Sort();??
????? return sort.findItem(coll.source,{name:nameTI.text, age:Number(ageTI.text)},? Sort.ANY_INDEX_MODE);??
?? }?
(3)过滤?
?? filterFunction 属性是由ListCollectionView 类定义，它是ArrayCollection 的父类。?
?? 当过滤器函数被传递给继承自ListCollectionView 的任何子类后，这里为ArrayCollection 对象，应用过滤器后必须调用refresh 方法?
?? 将原型为function(item:Object):Boolean 的函数传递给ArrayCollection 的filter 属性。如果返回true 表示值继续留在ArrayCollection，返回false 表示其值被移除。?
举例：?
? private function init():void {??
????? coll = new ArrayCollection([{name:"Martin Foo", age:25},{name:"Joe Bar", age:15},name:"John Baz", age:23},{name:"Matt Baz", age:21}]);??
????? coll.filterFunction = filterFunc;??
????? coll.refresh();??
????? for(var i:int = 0; i<coll.length; i++) {??
????????? trace(coll.getItemAt(i).name);??
????? }??
?? }??
?? private function filterFunc(value:Object):Object {??
????? if(Number(value.age) > 21) {??
????????? return true;??
????? }??
????? return false;??
?? }?
(4)排序?
?? 首先要创建一个Sort，传递一个SortField 对象数组给fields 属性。这些SortField 对象包含的字符串正是每个ArrayCollection 元素将要用来排序的属性。如要对每个对象的age 属性进行排序，创建Sort 对象，传递SortField。?
??? 设置排序字段为age：?
??? private function getOldest():void {??
?????? var sort:Sort = new Sort();??
?????? sort.fields = [new SortField("age")];??
?????? coll.sort = sort;??
?????? coll.refresh();??
?????? trace(coll.getItemAt(0).age+" "+coll.getItemAt(0).name);??
??? }??
??? 先按name升序排序，再按age降序排序?
??? sort.fields = [new SortField("name"),new SortField("age",true,true)];??
API说明：?
public function SortField(?
????????? name:String = null,??
????????? caseInsensitive:Boolean = false,??
????????? descending:Boolean = false,??
????????? numeric:Object = null)?
参数???
??? name:String (default = null) — 此字段用来进行比较的属性的名称。如果该对象为简单类型，则传递 null。??
??? caseInsensitive:Boolean (default = false) — 在对字符串进行排序时，指示比较运算符是否忽略值的大小写。?
??? descending:Boolean (default = false) — 指示比较运算符是否按降序排列项目。???
??? numeric:Object (default = null) — 指示比较运算符是否按编号而不按字母顺序比较排序项目。??
6.Array和ArrayCollection的比较?
Array的优点：?
?? 1)Array的性能优于ArrayCollection，从测试结果平均看来，ArrayCollection的效率是随着object的数目呈线性下降的，而Array则是体现了优异的效率，在object增加的情况下，基本上没有太大的变化。所以如果在你需要遍历所有元素的情况下(比如说物理引擎，3D引擎等)，Array是不错的选择?
???? 程序见附件1.?
?? 2)后台JavaBean也用的是数组[]?
?? 3)for循环数组似乎比for each? ArrayConllection看起来更“傻瓜化”?
?? 4)给Array数组扩展长度，也可以变通实现，而且代价并不大?
ArrayCollection的优点：?
?? 1)ArrayCollection 实现接口 ICollectionView，在 Flex 的类定义内属于[数据集]，他提供更强大的检索、过滤、排序、分类、更新监控等功能。类似的类还有 XMLListCollection?
?? 2)用 array 在作为 dataProvider 绑定于 control 之上，就无法获得控件的更新(实际上效果是可以得到更新的)，除非控件被重新绘制或者 data provider 被重新指定，而 Collection 则是将 array 的副本存储于 Collection 类的某个对象之中，其特点是 Collection 类本身就具备了确保数据同步的方法，例子如下（取自 adobe 内部工程师 training 示例，稍有改变）?
?? 3)对ArrayCollection中的对象进行增加删除更新操作时ArrayCollection会产生事件，可以通过collectionchange事件监听，所以在图表开发中都用ArrayCollection做数据源，一旦有更新，就会反映在图标上?
附件1：?
?? <?xml version="1.0" encoding="utf-8"?>?
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" frameRate="100" layout="vertical" horizontalAlign="center">?
??? <mx:Script>?
??????? <![CDATA[?
??????????? import mx.collections.ArrayCollection;?
??????????? [Bindable]?
??????????? private var ds:ArrayCollection;?
??????????? private var array:Array;?
??????????? private var ac:ArrayCollection;?
??????????? public function loop(loopCount:uint):Object?
??????????? {?
??????????????? array = null;?
??????????????? ac = null;?
??????????????? var begin:uint;?
??????????????? var end:uint;?
??????????????? var interval1:Number = 0;?
??????????????? var interval2:Number = 0;?
??????????????? var interval3:Number = 0;?
??????????????? var interval4:Number = 0;?
??????????????? var i:uint;?
??????????????? // for array, insert to array?
??????????????? i=0;?
??????????????? array= new Array();?
??????????????? begin = getTimer();?
??????????????? for (i;i<loopCount;i++)?
??????????????? {?
??????????????????? array.push({test:"helllo"});?
??????????????? }?
??????????????? end = getTimer();?
??????????????? interval1 =? end - begin;?
??????????????? t1.text = interval1.toString()+" ms";?
??????????????? //loop the array?
??????????????? i=0;?
??????????????? begin = getTimer();?
??????????????? for (i;i<array.length;i++)?
??????????????? {?
??????????????????? array[i];?
??????????????? }?
??????????????? end = getTimer();?
??????????????? interval3 =? end - begin;?
??????????????? t3.text = interval3.toString()+" ms";?
??????????????? /// for ac, insert to array collection?
??????????????? i=0;?
??????????????? ac=? new ArrayCollection();?
??????????????? begin = getTimer();?
??????????????? for (i;i<loopCount;i++)?
??????????????? {?
??????????????????? ac.addItem({test:"helllo"});?
??????????????? }?
??????????????? end = getTimer();?
??????????????? interval2 =? end - begin;?
??????????????? t2.text = interval2.toString()+ " ms";?
??????????????? //loop the array collection?
??????????????? i=0;?
??????????????? begin = getTimer();?
??????????????? for (i;i<ac.length;i++)?
??????????????? {?
??????????????????? ac.getItemAt(i);?
??????????????? }?
??????????????? end = getTimer();?
??????????????? interval4 =? end - begin;?
??????????????? t4.text = interval4.toString()+ " ms";?
??????????????? return {ct:loopCount,?
??????????????? array_insert:interval1,?
??????????????? ac_insert:interval2,?
??????????????? array_loop:interval3,?
??????????????? ac_loop:interval4?
??????????????? };?
??????????? }?
??????????? private function autoLoop():void?
??????????? {?
??????????????? ds=null;?
??????????????? ds = new ArrayCollection();?
??????????????? var i:uint=0;?
??????????????? for (i;i<parseInt(count.text);i+=parseInt(count.text)>100?parseInt(count.text)/10:1)?
??????????????? {?
??????????????????? ds.addItem(loop(i));?
??????????????? }?
??????????? }?
??????????? public function reset():void?
??????????? {?
??????????????? t1.text ="0";?
??????????????? t2.text ="0";?
??????????????? t3.text = "0";?
??????????????? t4.text = "0";?
??????????????? count.text = "1000";?
??????????????? ds=null;?
??????????????? ds = new ArrayCollection();?
??????????? }?
??????? ]]>?
??? </mx:Script>?
??? <mx:ApplicationControlBar width="503">?
??????? <mx:Label text="插入条数：" fontSize="12" color="#0B333C" fontWeight="bold"/>?
??????? <mx:TextInput width="98" text="1000" id="count"/>?
??????? <mx:Button id="startBtn0" label="Test" click="autoLoop()"/>?
??????? <mx:VRule height="15"/>?
??????? <mx:Button label="reset" click="reset()"/>?
??? </mx:ApplicationControlBar>?
??? <mx:Panel width="500" height="480" layout="horizontal" id="testBed" title="Array 与Array Collection的性能比较" fontSize="11" fontWeight="normal">?
??????? <mx:Canvas width="100%" height="100%" id="main" borderStyle="none" autoLayout="false"? horizontalScrollPolicy="off" fontSize="10">?
??????????? <mx:LineChart id="lc" x="8.5" y="133" width="463" height="306"? showDataTips="true" dataProvider="{ds}" >?
??????????????? <mx:horizontalAxis>?
??????????????????? <mx:CategoryAxis dataProvider="{ds}" categoryField="ct" title="插入Object数目"/>?
??????????????? </mx:horizontalAxis>?
??????????????? <mx:verticalAxis>?
??????????????????? <mx:LinearAxis id="la" minimum="-1" title="响应时间（毫秒）"/>?
??????????????? </mx:verticalAxis>?
??????????????? <mx:series>?
??????????????????? <mx:LineSeries displayName="array 插入耗时" yField="array_insert" />?
??????????????????? <mx:LineSeries displayName="arraycollection 插入耗时" yField="ac_insert"/>?
??????????????????? <mx:LineSeries displayName="array 遍历耗时" yField="array_loop"/>?
??????????????????? <mx:LineSeries displayName="arraycollection 遍历耗时" yField="ac_loop"/>?
??????????????? </mx:series>?
??????????? </mx:LineChart>?
??????????? <mx:HBox x="10" y="0" width="460" height="134" horizontalAlign="left" verticalAlign="middle">?
??????????????? <mx:Grid horizontalGap="1"? borderThickness="1" borderColor="#C6C6C6"? borderStyle="solid">?
??????????????????? <mx:GridRow width="100%" height="100%">?
??????????????????????? <mx:GridItem width="86" height="100%">?
??????????????????????????? <mx:Label text="毫秒(ms)" fontSize="12"/>?
??????????????????????? </mx:GridItem>?
??????????????????????? <mx:GridItem width="100%" height="100%" fontSize="12">?
??????????????????????????? <mx:Label text="Array"/>?
??????????????????????? </mx:GridItem>?
??????????????????????? <mx:GridItem width="100%" height="100%" fontSize="12">?
??????????????????????????? <mx:Label text="ArrayCollection"/>?
??????????????????????? </mx:GridItem>?
??????????????????? </mx:GridRow>?
??????????????????? <mx:GridRow width="100%" height="100%">?
??????????????????????? <mx:GridItem width="66" height="100%">?
??????????????????????????? <mx:Label text="插入耗时" fontSize="12"/>?
??????????????????????? </mx:GridItem>?
??????????????????????? <mx:GridItem width="100%" height="100%">?
??????????????????????????? <mx:Text text="0" width="80" id="t1" fontSize="12"/>?
??????????????????????? </mx:GridItem>?
??????????????????????? <mx:GridItem width="100%" height="100%">?
??????????????????????????? <mx:Text text="0" id="t2" width="80" fontSize="12"/>?
??????????????????????? </mx:GridItem>?
??????????????????? </mx:GridRow>?
??????????????????? <mx:GridRow width="100%" height="100%">?
??????????????????????? <mx:GridItem width="100%" height="100%">?
??????????????????????????? <mx:Label text="遍历耗时" fontSize="12"/>?
??????????????????????? </mx:GridItem>?
??????????????????????? <mx:GridItem width="100%" height="100%" fontSize="12">?
??????????????????????????? <mx:Text text="0" width="80" id="t3"/>?
??????????????????????? </mx:GridItem>?
??????????????????????? <mx:GridItem width="100%" height="100%">?
??????????????????????????? <mx:Text text="0" id="t4" width="80" fontSize="12"/>?
??????????????????????? </mx:GridItem>?
??????????????????? </mx:GridRow>?
??????????????? </mx:Grid>?
??????????????? <mx:VRule height="73" width="3"/>?
??????????????? <mx:Legend dataProvider="{lc}" width="100%" direction="vertical" fontSize="9" verticalGap="2" fontWeight="normal" fontStyle="normal" fontFamily="Verdana"/>?
??????????? </mx:HBox>?
??????? </mx:Canvas>?
??? </mx:Panel>?
??? <mx:LinkButton label="beherca" click="navigateToURL(new URLRequest('http://blog.beherca.com'),'_blank')"/>?
</mx:Application>?
