Validator 類是所有 Flex 驗證程序的基類。此類實現使驗證程序生成必填字段的功能，必填字段是指用戶必須在該字段中輸入值，否則驗證會失敗。

MXML 語法

<mx:Validator
enabled="true|false"
listener=" Value of the source property "
property=" No default "
required="true|false"
requiredFieldError="This field is required."
source=" No default "
trigger=" Value of the source property "
triggerEvent="valueCommit"
/>（可以查看action script3.0的api http://livedocs.adobe.com/flex/3_cn/mx/validators/Validator.html ）

1、Validator.mxml

<!--<br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--> <? xmlversion="1.0"encoding="utf-8" ?>

<!--
各種驗證控件的基類Validator的Demo，其可用于必填驗證
-->

< mx:Panel xmlns:mx ="http://www.adobe.com/2006/mxml" layout ="absolute" width ="400" height ="300"
title ="Validator-Validator(其他驗證器的基類，可用于必填驗證)" >

< mx:Validator id ="validator"
source ="{txtInput}" property ="text"
required ="true" requiredFieldError ="請輸入必填字段"
trigger ="{btnSubmit}" triggerEvent ="click"
/>

< mx:Form >
< mx:FormItem label ="必填字段:" >
< mx:TextInput id ="txtInput" />
</ mx:FormItem >
< mx:FormItem >
< mx:Button id ="btnSubmit" label ="驗證" />
</ mx:FormItem >
</ mx:Form >

</ mx:Panel >

2、DateValidator.mxml

<!--<br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--> <? xmlversion="1.0"encoding="utf-8" ?>

<!--
應用日期驗證控件的Demo
-->

< mx:Panel xmlns:mx ="http://www.adobe.com/2006/mxml" layout ="absolute" width ="400" height ="300"
title ="Validator-DateValidator(日期驗證)" >

< mx:DateValidator source ="{txtDate}" property ="text"
required ="true" requiredFieldError ="請輸入日期"
allowedFormatChars ="-" inputFormat ="YYYY-MM-DD"
trigger ="{btnSubmit}" triggerEvent ="click"
valid ="mx.controls.Alert.show('驗證成功');"
invalid ="mx.controls.Alert.show('驗證失敗');"
wrongDayError ="日輸入錯誤"
wrongMonthError ="月輸入錯誤"
wrongYearError ="年輸入錯誤"
wrongLengthError ="日期長度錯誤"
invalidCharError ="日期分隔符錯誤"
formatError ="inputFormat配置錯誤"
/>

< mx:Form >
< mx:FormItem label ="日期(格式yyyy-MM-dd):" >
< mx:TextInput id ="txtDate" />
</ mx:FormItem >
< mx:FormItem >
< mx:Button id ="btnSubmit" label ="驗證" />
</ mx:FormItem >
</ mx:Form >

</ mx:Panel >

3、EmailValidator.mxml

<!--<br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--> <? xmlversion="1.0"encoding="utf-8" ?>

<!--
應用Email驗證控件的Demo

-->
< mx:Panel xmlns:mx ="http://www.adobe.com/2006/mxml" layout ="absolute" width ="400" height ="300"
title ="Validator-EmailValidator(Email驗證)" >

< mx:EmailValidator id ="emailValidator" source ="{txtEmail}" property ="text"
missingAtSignError ="缺少@"
valid ="mx.controls.Alert.show('驗證成功');"
/>

< mx:Form >
< mx:FormItem label ="Email:" >
< mx:TextInput id ="txtEmail" />
</ mx:FormItem >
< mx:FormItem >
< mx:Button id ="btnSubmit" label ="驗證" click ="emailValidator.validate();" />
</ mx:FormItem >
</ mx:Form >

</ mx:Panel >

4、RegExpValidator.mxml

<!--<br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--> <? xmlversion="1.0"encoding="utf-8" ?>

<!--
應用正則表達式驗證控件的Demo
-->

< mx:Panel xmlns:mx ="http://www.adobe.com/2006/mxml" layout ="absolute" width ="400" height ="300"
title ="Validator-RegExpValidator(正則表達式驗證)" >

< mx:Script >
<![CDATA[

importmx.events.ValidationResultEvent;
importmx.validators.*;
importmx.controls.Alert;

privatefunctionhandleResult(e:ValidationResultEvent):void
{
if(e.type==ValidationResultEvent.VALID)
{
Alert.show("驗證成功");
}
}

]]>
</ mx:Script >

< mx:RegExpValidator id ="regExpValidator"
source ="{txtInput}" property ="text"
flags ="g,i" expression ="^[a-z]+$"
valid ="handleResult(event)" invalid ="handleResult(event)"
trigger ="{btnSubmit}" triggerEvent ="click"
noMatchError ="請輸入正確的英文字母"
required ="false"
/>

< mx:Form >
< mx:FormItem label ="請輸入英文字母:" >
< mx:TextInput id ="txtInput" />
</ mx:FormItem >
< mx:FormItem >
< mx:Button id ="btnSubmit" label ="驗證" />
</ mx:FormItem >
</ mx:Form >

</ mx:Panel >

flex驗證控件