同事做的。
package com.controls{ import flash.events.Event; import flash.events.FocusEvent; import flash.events.KeyboardEvent; import flash.ui.Keyboard; import mx.collections.ICollectionView; import mx.controls.ComboBox; import mx.core.UIComponent; public class AutoComplete extends ComboBox { public function AutoComplete() { super(); init(); } private function init(){ editable=true; rowCount=5; selectedIndex=-1; isTextBoxStringChange=false; isfocusInDropDown=false; isAutoComplete=false; //伪装成TextBox setStyle("cornerRadius",0); setStyle("arrowButtonWidth",0); setStyle("fontWeight","normal"); setStyle("paddingLeft",0); } //获得焦点时，是否自动弹出下拉框，get set private var isfocusInDropDown:Boolean=false; //是否自动完成,get set private var isAutoComplete:Boolean=false; //类默认过滤函数,get set private var _filterFunction:Function = myFilterFunction; //文本是否发生了变化 private var isTextBoxStringChange:Boolean=false; //按下的键是否是退格键 private var isBackSpaceKeyDown:Boolean=false; /** * 处理退格键按下的情况 */ override protected function keyDownHandler(event:KeyboardEvent):void { if(!event.ctrlKey&&!event.shiftKey) { if(event.keyCode == Keyboard.BACKSPACE) { close(); isBackSpaceKeyDown=true; } else { isBackSpaceKeyDown=false; } //当按UP键向上选择时，到达最顶时，显示用户原来所需文字 if(event.keyCode == Keyboard.UP && selectedIndex==0) { selectedIndex=-1; } } super.keyDownHandler(event); } /** * 数据源发生变化,数据不为0弹出下拉列表 */ override protected function collectionChangeHandler(event:Event):void { super.collectionChangeHandler(event); if(dataProvider.length>0) { open(); } } /** * 获得焦点 */ override protected function focusInHandler(event:FocusEvent):void{ if(isfocusInDropDown) open(); // super.focusInHandler(event); } /** * 文本发生变化时,触发查找匹配项的方法，重写父类的textInput_changeHandler(event:Event)事件。 */ override protected function textInput_changeHandler(event:Event):void { if(textInput.text == ""){ isTextBoxStringChange=false; } else{ isTextBoxStringChange=true; } super.textInput_changeHandler(event); invalidateProperties();//调用该方法，随后会触发调用commitProperties() } override protected function commitProperties():void{ if(isTextBoxStringChange){ prompt=text; filter(); //进行匹配项的查找,假如控件指定了要进行自动补全则进行自动补全操作。 if(isAutoComplete&&!isBackSpaceKeyDown){ var autoCompleteString:String=""; if(dataProvider.length>0) { autoCompleteString=itemToLabel(dataProvider[0]); textInput.setSelection(prompt.length,autoCompleteString.length); prompt=autoCompleteString; } else{ //输入文本框的文字显示不出来，因为系统默认将光标一直放在第一个位置，造成用户输入的文字被取消掉，所以在即使不需要补全是，也要进行 textInput.setSelection(textInput.selectionEndIndex,textInput.selectionEndIndex); } } else{ textInput.setSelection(textInput.selectionEndIndex,textInput.selectionEndIndex); } } super.commitProperties(); } /** * 与TextBox同样的宽度 */ override protected function measure():void { super.measure(); measuredWidth=UIComponent.DEFAULT_MEASURED_WIDTH; } /** * 过滤操作 */ private function filter():void{ var tmpCollection:ICollectionView = dataProvider as ICollectionView; tmpCollection.filterFunction = _filterFunction; tmpCollection.refresh(); } /** * 过滤函数 */ private function myFilterFunction(item:Object):Boolean { var myLabel:String = itemToLabel(item); if(myLabel.substr(0,text.length).toLowerCase() == prompt.toLowerCase()) { return true; } return false; } /************************Get Set 属性**********************************/ public function get FilterFunction():Function{ return _filterFunction; } public function set FilterFunction(filterFunction:Function):void{ _filterFunction=filterFunction; } public function get IsfocusInDropDown():Boolean{ return isfocusInDropDown; } public function set IsfocusInDropDown(value:Boolean):void{ isfocusInDropDown=value; } public function get IsAutoComplete():Boolean{ return isAutoComplete; } public function set IsAutoComplete(value:Boolean):void{ isAutoComplete=value; } }} <?xml version="1.0" encoding="utf-8"?><mx:Application xmlns:mx="https://www.adobe.com/2006/mxml" layout="vertical" xmlns:controls="com.controls.*" > <mx:Script> <![CDATA[ import mx.collections.ArrayCollection; [Bindable] private var values:ArrayCollection = new ArrayCollection(["你好","你们好","Abc","Axx","Ddd cc","xxx yyy","北京", "广东 广州","Bxx Baa","上海","张三","李四","Aadla","Asf sf", "Bxv sfs","Abort XXX","Asp Php"]); ]]> </mx:Script> <mx:Style> .ChineseFont{ fontFamily:”Verdana”,”宋体”; fontSize:12; } Application{ fontSize:12; } </mx:Style> <mx:HBox> <mx:CheckBox label="获取焦点弹出下拉框" id="focusDrop"/> <mx:CheckBox label="自动补全文字" id="auto"/> </mx:HBox> <controls:AutoComplete styleName="ChineseFont" id="autoComplete1" dataProvider="{values}" IsfocusInDropDown="{focusDrop.selected}" IsAutoComplete="{auto.selected}" /></mx:Application>package com.controls{ import flash. 
