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(1,4,3,45,6,7,77,9);???? 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",{name:"Joe Bar",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>?