Flex ComBobox录入关键字动态提示

只要调用下面AutoComplete后即可实现录入关键字动态提示
package components.common
{
import flash.events.Event;
import flash.events.FocusEvent;
import flash.events.KeyboardEvent;
import flash.ui.Keyboard;

import mx.collections.ICollectionView;
import mx.controls.Alert;
import mx.controls.ComboBox;
import mx.core.UIComponent;

import view.customer.viewCustomer;


public class AutoComplete extends ComboBox
{
public function AutoComplete()
{
super();
init();
}

private function init():void{
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&&text!="")
{
// Alert.show(textInput.text+","+textInput.text.length);
open();
}
}

/**
     *  Displays the drop-down list.
     */
    override public function open():void{
   
    if(text!=""){
//     Alert.show(textInput.text+","+text+"open()!!!"+isTextBoxStringChange);
    super.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
*/
override protected function textInput_changeHandler(event:Event):void
{
// Alert.show(textInput.text+" text change!");
if(textInput.text == ""){
// Alert.show(textInput.text+",null");
isTextBoxStringChange=false;
}
else{
// Alert.show(textInput.text+","+event.toString());
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&&textInput.text!=""){
prompt=text;
filter(); //进行匹配项的查找
if(isAutoComplete&&!isBackSpaceKeyDown){
var autoCompleteString:String="";
if(dataProvider.length>0)
{
autoCompleteString=itemToLabel(dataProvider[0]);
textInput.setSelection(prompt.length,autoCompleteString.length);
prompt=autoCompleteString;
}
else{
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;
}

}
}

注意：在引用该ComboBox后，如果下拉列表中的数据是从库中查出来的，那么在显示时会闪出一个下拉列表框，很不顺眼。解决办法：首先在往库中查询全部数据后，应当清空ComboBox，接着再给ComboBox中的data和label赋值，就可以避免闪出方框。