如何手动调用 flex 绑定？答案

【问题标题】：How to invoke flex binding manually?如何手动调用 flex 绑定？
【发布时间】：2014-08-04 08:10:01
【问题描述】：

我有一个用 flex 动作脚本编写的代码，我正在尝试使用 selectedValue 将变量绑定到 RadioButtonGroup

<?xml version="1.0" encoding="utf-8"?>
<s:WindowedApplication xmlns:fx="http://ns.adobe.com/mxml/2009" 
                       xmlns:s="library://ns.adobe.com/flex/spark"  
                       xmlns:mx="library://ns.adobe.com/flex/mx">
    <fx:Script>

        <![CDATA[
            [Bindable]
            public static var appObj:String = "first";

            public function setToThird():void {
                appObj = "third";
            }
            public function setToFirst():void {
                appObj = "first";
            }
        ]]>

    </fx:Script>
    <fx:Declarations>
        <!-- Place non-visual elements (e.g., services, value objects) here -->
        <s:RadioButtonGroup id="travelGroup" selectedValue="{appObj}"/>
    </fx:Declarations>
    <s:RadioButton x="167" y="91" label="first" group="{travelGroup}"/>
    <s:RadioButton x="167" y="119" label="second" group="{travelGroup}"/>
    <s:RadioButton x="167" y="151" label="third" group="{travelGroup}"/>
    <s:Label x="195" y="177" text="appObj value is {appObj}" />
    <s:Button x="149" y="277" label="setToThird" click="setToThird()"/>
    <s:Button x="270" y="277" label="setToFirst" click="setToFirst()"/>
</s:WindowedApplication>

当我点击setToThird button 时，appObj value 将设置为字符串third，而选中的单选按钮将是third。

现在，当我单击 second 单选按钮时，appObj 的值仍然是字符串 third，单击按钮 setToThird 不会将单选按钮选择更改为 third 作为值 @987654331 @ 没有改变，绑定 (Bindable) 不会被调用。

谁能帮助我了解如何使用 BindingManager 或其他工具手动调用绑定。

我不想实现双向数据绑定。

【问题讨论】：

标签： actionscript-3 flash apache-flex air flash-builder

【解决方案1】：

最简单最简单的方法是双向绑定（只需在 {appObj} 之前添加 @ 符号）。但如果你想避免这种情况，你可以采取一些逻辑：

<?xml version="1.0"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark" xmlns:local="*">
<fx:Script>

    <![CDATA[
    [Bindable(event="appObjChanged")]
    public var appObj:String = "first";

    public function setToThird():void {
        appObj = "third";
        dispatchEvent(new Event("appObjChanged"));
    }
    public function setToFirst():void {
        appObj = "first";
        dispatchEvent(new Event("appObjChanged"));
    }
    ]]>

</fx:Script>
<fx:Declarations>
    <!-- Place non-visual elements (e.g., services, value objects) here -->
    <s:RadioButtonGroup id="travelGroup" selectedValue="{appObj}"/>
</fx:Declarations>
<s:RadioButton x="167" y="91" label="first" group="{travelGroup}"/>
<s:RadioButton x="167" y="119" label="second" group="{travelGroup}"/>
<s:RadioButton x="167" y="151" label="third" group="{travelGroup}"/>
<s:Label x="195" y="177" text="appObj value is {appObj}" />
<s:Button x="149" y="277" label="setToThird" click="setToThird()"/>
<s:Button x="270" y="277" label="setToFirst" click="setToFirst()"/>
</s:Application>

附：绑定只是调度和接收事件，没有别的，所以你可以很容易地自定义它。

【讨论】：