使用NumberFormatter判断TextInput输入内容是否为数字，如果是则格式化数字。

NumberFormatter标签学习.
示例：

代码：

<?xml version="1.0"?>
<!-- Simple example to demonstrate NumberFormatter. -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">

    <mx:Script>
        <![CDATA[

          import mx.events.ValidationResultEvent;
          private var vResult:ValidationResultEvent;

          // Event handler to validate and format input.
          private function Format():void
          {
             vResult = numVal.validate();
             if (vResult.type==ValidationResultEvent.VALID) {

                formattedNumber.text= numberFormatter.format(inputVal.text);
             }

             else {
                formattedNumber.text= "";
             }
          }
      ]]>
    </mx:Script>

    <mx:NumberFormatter id="numberFormatter" precision="4"
        useThousandsSeparator="true" useNegativeSign="true"/>

    <mx:NumberValidator id="numVal" source="{inputVal}" property="text"
        allowNegative="true" domain="real"/>

    <mx:Panel title="NumberFormatter Example" width="75%" height="75%"
            paddingTop="10" paddingLeft="10" paddingRight="10" paddingBottom="10">

        <mx:Form>
            <mx:FormItem label="Enter number:">
                <mx:TextInput id="inputVal" text="" width="50%"/>
            </mx:FormItem>

            <mx:FormItem label="Formatted number (precision=4): ">
                <mx:TextInput id="formattedNumber" editable="false" width="50%"/>
            </mx:FormItem>

            <mx:FormItem>
                <mx:Button label="Validate and Format" click="Format();"/>
            </mx:FormItem>
        </mx:Form>

    </mx:Panel>
</mx:Application>

点击查看源文件

来自：http://www.flex-tutorial.fr/2008/05/18/flex-formatter-exemple-de-numberformatter-en-mxml-et-actionscript/