Flex提供了出色的調試Flex代碼的能力，Flash Builder 4具有出色的內置調試器和調試透視圖支持。

• 在調試模式下，Flex應用程式運行在Flash Builder 4中內置的Flash Player調試器版本上，該版本支持調試功能。

• 因此開發人員可以在Flash Builder中獲得一個簡單且內置的調試配置

在本文中，我們將演示如何使用Flash Builder調試Flex客戶機代碼。我們將完成以下任務

• Set break points in the code and see them in Breakpoint Explorer.
• Step through the code line by line during debugging.
• View the values of variable.
• Inspect the values of all the variables.
• Inspect the value of an expression.
• Display the stack frame for suspended threads.

Debugging Example

<?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)">
   
   <fx:Style source = "/com/tutorialspoint/client/Style.css" />
   <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 = "My Hello World Application";
         }
      ]]>
   </fx:Script>

   <s:BorderContainer width = "500" height = "500" id = "mainContainer"
      styleName = "container">
      <s:VGroup width = "100%" height = "100%" gap = "50" horizontalAlign = "center"
         verticalAlign = "middle">
         <s:Label id = "lblHeader" fontSize = "40" color = "0x777777"
            styleName = "heading" />
         <s:Button label = "Click Me!" id = "btnClickMe"
            click = "btnClickMe_clickHandler(event)" styleName = "button" />
      </s:VGroup>
   </s:BorderContainer>
</s:Application>

完成所有更改後，讓我們以正常模式編譯，就像在flex-create application一章中那樣。

Step 1 - Place Breakpoints

在HelloWorld.mxml的應用程式初始化處理程序的第一行放置斷點

Step 2 - Debug Application

現在，單擊「調試應用程式」菜單，然後選擇「HelloWorld」應用程式調試應用程式。

如果一切正常，應用程式將在瀏覽器中啓動，您將在Flash Builder控制台中看到以下調試日誌。

[SWF] \HelloWorld\bin-debug\HelloWorld.swf 
- 181,509 bytes after decompression
[SWF] \HelloWorld\bin-debug\HelloWorld.swf\[[DYNAMIC]]\1 
- 763,122 bytes after decompression
[SWF] \HelloWorld\bin-debug\HelloWorld.swf\[[DYNAMIC]]\2 
- 1,221,837 bytes after decompression
[SWF] \HelloWorld\bin-debug\HelloWorld.swf\[[DYNAMIC]]\3 
- 1,136,788 bytes after decompression
[SWF] \HelloWorld\bin-debug\HelloWorld.swf\[[DYNAMIC]]\4 
- 2,019,570 bytes after decompression
[SWF] \HelloWorld\bin-debug\HelloWorld.swf\[[DYNAMIC]]\5 
- 318,334 bytes after decompression

一旦應用程式啓動，您將看到焦點放在Flash Builder斷點上，因爲我們已經將斷點放在Application_initialize Handler方法的第一行。

您可以看到掛起線程的stacktrace。

可以看到表達式的值。

您可以看到放置的斷點列表。

現在繼續按F6，直到到達最後一行application_initializeHandler（）方法。作爲功能鍵的參考，F6逐行檢查代碼，F5步驟進一步深入，F8將繼續應用。現在您可以看到application_initializeHandler（）方法的所有變量的值列表。

現在您可以看到flex代碼的調試方式與Java應用程式的調試方式相同。將斷點放置到任意行並使用flex的調試功能。