使用 CSS 的样式（Style with CSS）

Flex支持使用CSS语法和样式以与CSS到HTML组件相同的方式应用于其UI控件。

方式＃1:使用外部样式表文件

您可以参考应用程序类路径中可用的样式表。 例如，考虑一下Hello com/xnip/client folder World.mxml文件所在的com/xnip/client folder中的Style.css文件。

/* CSS file */
@namespace s "library://ns.adobe.com/flex/spark";
@namespace mx "library://ns.adobe.com/flex/mx";
...
.container {
   cornerRadius :10;
   horizontalCenter :0;	
   borderColor: #777777;
   verticalCenter:0;
   backgroundColor: #efefef;
}

然后可以通过以下代码片段引用css文件

<fx:Style source = "/com/xnip/client/Style.css" />

使用styleName属性为UI组件指定样式

<s:BorderContainer width = "500" height = "500" id = "mainContainer" 
   styleName = "container"> 
   ...
</s:BorderContainer>		  

方式＃2:在Ui容器组件中使用样式

您可以使用标记在UI容器组件中定义样式

class选择器

<fx:Style>
   @namespace s "library://ns.adobe.com/flex/spark";
   @namespace mx "library://ns.adobe.com/flex/mx";
   /* class level selector  */
   .errorLabel {
      color: red;
   }		
</fx:Style>

使用styleName属性为UI组件指定样式。

<s:Label id = "errorMsg" text = "This is an error message" styleName = "errorLabel" />

Id级别选择器

使用id选择器的样式UI组件。

<fx:Style> 
   /* id level selector  */ 
   #msgLabel { 
      color: gray; 
   } 
</fx:Style>
<s:Label id = "msgLabel" text = "This is a normal message" /> 

类型级别选择器

在一个GO中设置一种类型的UI组件。

<fx:Style> 
   /* style applied on all buttons  */ 
   s|Button {  
      fontSize: 15; 
      color: #9933FF; 
   } 
</fx:Style>
<s:Button label = "Click Me!" id = "btnClickMe"
   click = "btnClickMe_clickHandler(event)" />

使用CSS示例的Flex样式

让我们按照步骤通过创建测试应用程序来检查Flex应用程序的CSS样式 -

以下是修改后的CSS文件src/cn.xnip/Style.css 。

/* CSS file */
@namespace s "library://ns.adobe.com/flex/spark";
@namespace mx "library://ns.adobe.com/flex/mx";
.heading
{
   fontFamily: Arial, Helvetica, sans-serif;
   fontSize: 17px;
   color: #9b1204;
   textDecoration:none;
   fontWeight:normal;
}
.button {
   fontWeight: bold;			
}
.container {
   cornerRadius :10;
   horizontalCenter :0;	
   borderColor: #777777;
   verticalCenter:0;
   backgroundColor: #efefef;
}

以下是修改后的mxml文件src/cn.xnip/HelloWorld.mxml 。

<?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"
   initialize = "application_initializeHandler(event)">
   <!--Add reference to style sheet -->
   <fx:Style source = "/com/xnip/client/Style.css" />
   <!--Using styles within mxml file -->
   <fx:Style>
      @namespace s "library://ns.adobe.com/flex/spark";
      @namespace mx "library://ns.adobe.com/flex/mx";
      /* class level selector  */
      .errorLabel {
         color: red;
      }
      /* id level selector  */
      #msgLabel {
         color: gray;
      }
      /* style applied on all buttons  */
      s|Button {
         fontSize: 15;
         color: #9933FF;
      }
   </fx:Style>
   <fx:Script>
      <![CDATA[
         import mx.controls.Alert;
         import mx.events.FlexEvent;
         protected function btnClickMe_clickHandler(event:MouseEvent):void {
            Alert.show("Hello World!");
         }
         protected function application_initializeHandler(event:FlexEvent):void {
            lblHeader.text = "CSS Demonstrating Application";
         }
      ]]>
   </fx:Script>
   <s:BorderContainer width = "560" height = "500" id = "mainContainer"
      styleName = "container">
      <s:VGroup width = "100%" height = "100%" gap = "50"
         horizontalAlign = "center" verticalAlign = "middle">
         <s:Label width = "100%" id = "lblHeader" fontSize = "40"
            color = "0x777777" styleName = "heading" />
         <s:Button label = "Click Me!" id = "btnClickMe"
            click = "btnClickMe_clickHandler(event)"  />
         <s:Label id = "errorMsg"
            text = "This is an error message" styleName = "errorLabel" />
         <s:Label id = "msgLabel" text = "This is a normal message" />
      </s:VGroup>
   </s:BorderContainer>
</s:Application>

一旦准备好完成所有更改，让我们像在Flex - Create Application章节中那样在正常模式下编译和运行应用程序。