Flex 事件处理

Flex使用事件概念将数据从一个对象传递到另一个对象，这取决于应用程序中的状态或用户交互。

ActionScript有一个通用的 Event 类，它定义了处理事件所需的大部分功能。 每次在Flex应用程序中发生事件时，都会创建来自Event类层次结构的三种类型的对象。

事件具有以下三个关键属性

事件流阶段

事件经过三个阶段寻找事件处理程序。

考虑以下应用程序代码

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
   xmlns:s="library://ns.adobe.com/flex/spark" 
   xmlns:mx="library://ns.adobe.com/flex/mx"
   width="100%" height="100%"
   minWidth="500" minHeight="500" >
   <s:Panel>
      <s:Button id="clickMeButton" label="Click Me!" click="doAction( );"/>
   </s:Panel>   
</s:Application>

当用户单击按钮时，他或她也单击了面板和应用程序。事件通过三个阶段寻找事件处理程序分配。

让我们按照以下步骤在Flex应用程序中测试事件处理:

以下是修改后的mxml文件 src / com.tutorialspoint / HelloWorld.mxml 的内容。

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
   xmlns:s="library://ns.adobe.com/flex/spark"
   xmlns:mx="library://ns.adobe.com/flex/mx"
   width="100%" height="100%" minWidth="500" minHeight="500"
   >
   <fx:Style source="/com/tutorialspoint/client/Style.css"/>
   <fx:Script>
      <![CDATA[
         protected function reportEvent(event:MouseEvent):void
         {
            var target:String = event.target.id;
            var currentTarget:String = event.target.id;
            var eventPhase: String;

            if(event.target is Button){
               var button:Button = event.target as Button;
               target = button.label + " Button";
            } else if(event.target is HGroup){
               var hGroup:HGroup = event.target as HGroup;
               target = hGroup.id + " HGroup";
            }else if(event.target is Panel){
               var panel:Panel = event.target as Panel;
               target = panel.id + " Panel";
            }

            if(event.currentTarget is Button){
               var button1:Button = event.currentTarget as Button;
               currentTarget = button1.label + " Button";
            }else if(event.currentTarget is HGroup){
               var hGroup1:HGroup = event.currentTarget as HGroup;
               currentTarget = hGroup1.id + " HGroup";
            }else if(event.currentTarget is Panel){
               var panel1:Panel = event.currentTarget as Panel;
               currentTarget = panel1.id + " Panel";
            }

            var eventPhaseInt:uint = event.eventPhase;

            if(eventPhaseInt == EventPhase.AT_TARGET){      
               eventPhase = "Target";
            } else if(eventPhaseInt == EventPhase.BUBBLING_PHASE){
               eventPhase = "Bubbling";
            }else if(eventPhaseInt == EventPhase.CAPTURING_PHASE){
               eventPhase = "Capturing";
            }
            
            reports.text += " Target: " + target + "\n currentTarget: " +
            currentTarget + "\n Phase: " + eventPhase + "\n----------\n";				
         }
      ]]>
   </fx:Script>
   <s:BorderContainer width="630" height="480" id="mainContainer" 
      styleName="container">
      <s:VGroup width="100%" height="100%" gap="10" 
         horizontalAlign="center" verticalAlign="middle">
         <s:Label id="lblHeader" text="Event Handling Demonstration" 
            fontSize="40" color="0x777777" styleName="heading"/>
         <s:Panel id="parentPanel" title="Main Parent" 
            click="reportEvent(event)" width="500" 
            height="100" includeInLayout="true" visible="true">
            <s:layout>
               <s:VerticalLayout  gap="10" 
                  verticalAlign="middle" horizontalAlign="center"/>
            </s:layout>						
            <s:HGroup id="mainHGroup" click="reportEvent(event)">
               <s:Button label="Click Me" 
                  click="reportEvent(event)"/>
            </s:HGroup>						
         </s:Panel>	
         <s:Panel id="reportPanel" 
            title="Events" width="500" height="230">
            <mx:Text id="reports" />				
         </s:Panel>
      </s:VGroup>	 
   </s:BorderContainer>	
</s:Application>

准备好所有更改后，让我们以正常模式编译和运行应用程序，就像在 Flex - 创建应用程序中一样 章节。 如果一切顺利，您的应用程序，这将产生以下结果:[在线试用]