用于实时检测FPS（实际上可以算是检测CPU）和内存占用情况。

使用方法，在application的Document Class（或者Application Class）上构建一个检测器实例（MonitorKit）并addChild即可，所含参数比较简单，不再一一赘述：

 var monitor:MonitorKit = new MonitorKit(MonitorKit.MKMODE_T);
addChild(monitor);
package 
{
  import flash.display.Sprite;
  import flash.display.Stage;
  import flash.events.Event;
  import flash.system.System;
  import flash.text.TextField;
  import flash.text.TextFieldAutoSize;
  import flash.text.TextFormat;
  import flash.utils.getTimer;

  public class MonitorKit extends Sprite{
    public static const MKMODE_T:String = "MKMODE_T";
    public static const MKMODE_B:String = "MKMODE_B";
    public static const MKMODE_L:String = "MKMODE_L";
    public static const MKMODE_R:String = "MKMODE_R";
    public static const MKMODE_TL:String = "MKMODE_TL";
    public static const MKMODE_TR:String = "MKMODE_TR";
    public static const MKMODE_BL:String = "MKMODE_BL";
    public static const MKMODE_BR:String = "MKMODE_BR";

    private static var stageInstance:Stage;

    private var lastTime:uint = getTimer();
    private var frames:Number = 0;
    private var monitorKitTextField:TextField;
    private var mode:String;
    private var textColor:uint;
    private var backgroundColor:uint;
    private var transparent:Boolean;
    public static var delay:Number = 0;
    public function MonitorKit(_mode:String = MKMODE_T,
        _transparent:Boolean = true,
        _textColor:uint=0xffffff,
        _backgroundColor:uint=0x000000) {
      mode = _mode;
      transparent = _transparent;
      textColor = _textColor;
      backgroundColor = _backgroundColor;
      // Initialize it when rendered on the stage.
      addEventListener(Event.ADDED_TO_STAGE, initMonitorHandler);
    }

    private function initMonitorHandler(event:Event):void {
      // Unregister the event handler
      removeEventListener(Event.ADDED_TO_STAGE, initMonitorHandler);
      stageInstance = this.stage;
      monitorKitTextField = new TextField();
      monitorKitTextField.selectable = false;
      monitorKitTextField.background = transparent;
      monitorKitTextField.textColor = textColor;
      monitorKitTextField.backgroundColor = backgroundColor;
      monitorKitTextField.autoSize = TextFieldAutoSize.LEFT;
      var format:TextFormat = new TextFormat();
      format.font = "Courier New";
      format.size = 15;
      monitorKitTextField.setTextFormat(format);
      monitorKitTextField.defaultTextFormat = format;
      monitorKitTextField.text = "[ Loading... ]";
      addChild(monitorKitTextField);
      stageInstance.addEventListener(Event.ENTER_FRAME, enterFrameHandler);
    }

    public function enterFrameHandler(evt:Event):void {
      frames++;
      var currentTime:uint = getTimer();
      var deltaTime:uint = currentTime - lastTime;
      var fps:Number = frames / deltaTime * 1000;
      monitorKitTextField.text = "FPS: " + fps.toFixed(1);
      monitorKitTextField.appendText("\nMem: " + Number(System.totalMemory/1024/1024).toFixed(3)+"(M)");
      frames = 0;
      lastTime = currentTime;
      // Replace the monitor object
      switch (mode) {
        case MKMODE_T:
          monitorKitTextField.x = stageInstance.stageWidth / 2 - monitorKitTextField.width / 2;
          monitorKitTextField.y = 0;
          break;
        case MKMODE_B:
          monitorKitTextField.x = stageInstance.stageWidth / 2 - monitorKitTextField.width / 2;
          monitorKitTextField.y = stageInstance.stageHeight - monitorKitTextField.height;
          break;
        case MKMODE_L:
          monitorKitTextField.x = 0;
          monitorKitTextField.y = stageInstance.stageHeight / 2 - monitorKitTextField.height / 2;
          break;
        case MKMODE_R:
          monitorKitTextField.x = stageInstance.stageWidth - monitorKitTextField.width;
          monitorKitTextField.y = stageInstance.stageHeight / 2 - monitorKitTextField.height / 2;
          break;
        case MKMODE_TL:
          monitorKitTextField.x = 0;
          monitorKitTextField.y = 0;
          break;
        case MKMODE_TR:
          monitorKitTextField.x = stageInstance.stageWidth - monitorKitTextField.width;
          monitorKitTextField.y = 0;
          break;
        case MKMODE_BL:
          monitorKitTextField.x = 0;
          monitorKitTextField.y = stageInstance.stageHeight - monitorKitTextField.height;
          break;
        case MKMODE_BR:
          monitorKitTextField.x = stageInstance.stageWidth - monitorKitTextField.width;
          monitorKitTextField.y = stageInstance.stageHeight - monitorKitTextField.height;
          break;
        default:
        break;
      }
    }
  }
}