Air for Android开发中使用Back键弹出是否退出对话框


转载: http://blog.csdn.net/ar156/article/details/6117647


 

Air for Android开发中使用Back键弹出是否退出对话框

分类: Andoid   866人阅读  评论(0)  收藏  举报

用Flash cs5做测试的时候试了很久都没有找到方法,按照官方的说明,“请注意:当按下“返回”键时,可调用事件 preventDefault() 方法以避免出现返回至上一应用程序的“返回”键默认行为。“菜单”和“搜索”键无默认行为。”,试了一遍又一遍,最终发现在使用event.preventDefault()方法时,如果侦听的是KeyUp事件的话,是无法阻止默认行为的,所以想要成功阻止返回,请侦听KeyDown事件

 

 

以下是一个用于测试的文档类:

 

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//code
package
{
	import flash.display.Sprite;
	import flash.events.KeyboardEvent;
	import flash.events.MouseEvent;
	import flash.ui.Keyboard;
	import flash.desktop.NativeApplication;
	import flash.text.TextField;
	import flash.events.Event;
	import flash.text.TextFieldAutoSize;
	import flash.text.TextFormat;
 
	/**
	 * 描述: 测试阻止Air For Android 默认BACK按键事件
	 * 作者: Frozensun
	 * 创建日期: 2010-12-14 21:03
	*/
	public class Main extends Sprite
	{
		private var _menuBar:Sprite;
		private var _txtLogger:TextField;
 
		public function Main()
		{
			fCreateLogger();
			fCreateMenuBar();
 
			output("试试按下menu和返回键吧!");
 
			NativeApplication.nativeApplication.addEventListener(KeyboardEvent.KEY_DOWN, eMenuBarHandler);
		}
 
		//创建logger显示文本
		private function fCreateLogger():void
		{
			_txtLogger = new TextField();
			_txtLogger.width = stage.stageWidth;
			_txtLogger.height = stage.stageHeight;
			_txtLogger.defaultTextFormat = new TextFormat(null, 20, 0xCCCCCC);
			_txtLogger.multiline = true;
			_txtLogger.selectable = false;
			_txtLogger.background = true;
			_txtLogger.backgroundColor = 0x333333;
			addChild(_txtLogger);
		}
 
		//创建菜单
		private function fCreateMenuBar():void
		{
			var __W:Number = stage.stageWidth / 1.5;
			var __H:Number = __W / 2;
			_menuBar = new Sprite();
			_menuBar.graphics.beginFill(0xCCCCCC, 0.75);
			_menuBar.graphics.drawRoundRect(-__W / 2, -__H / 2, __W, __H, __H / 4, __H / 4);
			_menuBar.graphics.beginFill(0x666666, 0.8);
			_menuBar.graphics.drawCircle(0, 0, __H / 2 / 1.5);
			_menuBar.graphics.endFill();
			_menuBar.x = stage.stageWidth / 2;
			_menuBar.y = stage.stageHeight / 2;
 
			var __txtClose:TextField = new TextField();
			__txtClose.autoSize = TextFieldAutoSize.CENTER;
			__txtClose.defaultTextFormat = new TextFormat(null, 60, 0xCCCCCC, true);
			__txtClose.selectable = false;
			__txtClose.text = "X";
			__txtClose.x = -__txtClose.width / 2;
			__txtClose.y = -__txtClose.height / 2;
			_menuBar.addChild(__txtClose);
		}
 
		//键盘事件
		private function eMenuBarHandler(e:KeyboardEvent):void
		{
			switch (e.keyCode)
			{
				case Keyboard.MENU :
					checkMenuBar();
					break;
 
				case Keyboard.BACK :
					e.preventDefault();
					checkMenuBar();
					break;
			}
 
			output("keyCode:", e.keyCode, " isDefaultPrevented:", e.isDefaultPrevented());
		}
 
		//检测menuBar的显隐
		private function checkMenuBar():void
		{
			if (! this.contains(_menuBar))
			{
				this.addChild(_menuBar);
				_menuBar.addEventListener(MouseEvent.CLICK, eExitAppHandler);
			}
			else
			{
				this.removeChild(_menuBar);
				_menuBar.removeEventListener(MouseEvent.CLICK, eExitAppHandler);
			}
		}
 
		//按下_menuBar时退出
		private function eExitAppHandler(e:MouseEvent):void
		{
			NativeApplication.nativeApplication.exit();
		}
 
		//显示调试文本
		private function output(...rest):void
		{
			var __log:String = "";
			for each (var i:* in rest)
			{
				__log +=  String(i) + " ";
			}
			__log +=  "/n";
 
			_txtLogger.appendText(__log);
			_txtLogger.scrollV = _txtLogger.maxScrollV;
		}
 
	}
 
}

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