Flex - 组合框控件

当用户从组合框控件的下拉列表中选择一个项目时，数据项目会显示在控件的提示区域中。

组合框和下拉列表控件之间的一个区别在于，组合框控件的提示区域是使用文本输入控件实现的，而下拉列表控件的提示区域是标签控件。因此，用户可以编辑控件的提示区域以输入一个不是可用选项之一的值。

类声明

以下是spark.components.ComboBox类的声明：

public class ComboBox 
   extends DropDownListBase 
      implements IIMESupport

公共属性

公共方法

继承的方法

此类继承自以下类：

• spark.components.supportClasses.DropDownListBase
• spark.components.List
• spark.components.supportClasses.ListBase
• spark.components.SkinnableDataContainer
• spark.components.supportClasses.SkinnableContainerBase
• spark.components.supportClasses.SkinnableComponent
• mx.core.UIComponent
• mx.core.FlexSprite
• flash.display.Sprite
• flash.display.DisplayObjectContainer
• flash.display.InteractiveObject
• flash.display.DisplayObject
• flash.events.EventDispatcher
• Object

Flex 组合框控件示例

让我们按照以下步骤，通过创建一个测试应用程序来检查在 Flex 应用程序中组合框控件的使用：

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[
         import mx.collections.ArrayCollection; 

         [Bindable]
         public var data:ArrayCollection = new ArrayCollection (
         [   
            {value:"France", code:"FR"},
            {value:"Japan", code:"JP"},
            {value:"India", code:"IN"},
            {value:"Russia", code:"RS"},
            {value:"United States", code:"US"}		
         ]                
         );

         private function mappingFunction(input:String):Object {
            switch (input){
               case "France":
                  return {value:input, code:"FR"};		
               case "Japan":
                  return {value:input, code:"JP"};		
               case "India":
                  return {value:input, code:"IN"};		
               case "Russia":
                  return {value:input, code:"RS"};		
               case "United States":
                  return {value:input, code:"US"};		
            }			
            return null;
         }

      ]]>
   </fx:Script>
   
   <fx:Declarations>
      <mx:DateFormatter id = "dateFormatter" />
   </fx:Declarations>
   
   <s:BorderContainer width = "550" height = "400" id = "mainContainer"
      styleName = "container">
      <s:VGroup width = "100%" height = "100%" gap = "50" horizontalAlign = "center"
         verticalAlign = "middle">
         <s:Label id = "lblHeader" text = "Form Controls Demonstration" 
            fontSize = "40" color = "0x777777" styleName = "heading" />
         
         <s:Panel id = "comboBoxPanel" title = "Using ComboBox" width = "420" 
            height = "200">
         <s:layout>
            <s:VerticalLayout  gap = "10" verticalAlign = "middle" 
               horizontalAlign = "center" />	
         </s:layout>
         
         <s:HGroup>
            <s:Label text = "Index :" /> <s:Label 
               text = "{comboBox.selectedIndex}" fontWeight = "bold" />
            <s:Label text = "Value :" /> <s:Label 
               text = "{comboBox.selectedItem.value}" fontWeight = "bold" />
            <s:Label text = "Code :" /> <s:Label 
               text = "{comboBox.selectedItem.code}" fontWeight = "bold" />
         </s:HGroup>
         
         <s:ComboBox  id = "comboBox"  dataProvider = "{data}" width = "150" 
            labelToItemFunction = "{mappingFunction}" selectedIndex = "0" 
            labelField = "value" />     
         </s:Panel>
      </s:VGroup>	 
   </s:BorderContainer>	
</s:Application>

完成所有更改后，让我们像在Flex - 创建应用程序章节中那样，以普通模式编译并运行应用程序。如果应用程序一切正常，它将产生以下结果：[ 在线试用 ]