Flex4之简易MP3播放器

<?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" minWidth="955" minHeight="600" 
			   applicationComplete="init();"> 
	<s:layout>
		<s:VerticalLayout horizontalAlign="center" verticalAlign="middle"/>
	</s:layout>
	<fx:Declarations> 
		<!-- Place non-visual elements (e.g., services, value objects) here --> 			
	</fx:Declarations> 
	<fx:Script> 
		<![CDATA[ 
			import flash.events.Event; 
			import flash.media.Sound; 
			import flash.media.SoundChannel; 
			import flash.media.SoundTransform; 
			import flash.net.URLRequest; 
			import flash.xml.*; 
			
			private var _xmlDoc:String; 
			private var _xmlObj:XML; 
			private var _soundObj:Sound; 
			private var _soundTransform:SoundTransform; 
			private var _soundChannel:SoundChannel; 
			
			private var _currentArrayNum:int; 
			private var _currentSndPosition:Number;
			
			private var _isPlayingSound:Boolean; 
			//helps you keep track of if the song is playing or not. 
			
			
			private function init():void 
			{ 
				_xmlDoc = '<?xml version="1.0" encoding="utf-8"?><mp3><songURL>I Need You Come Back.mp3</songURL>' +
					'<songURL>Boom Boom Pow.mp3</songURL></mp3>'; 
				_xmlObj = new XML(_xmlDoc); 
				trace(_xmlObj..songURL); 
				trace(_xmlObj..songURL[0]); 
				//if there were more "songURL" tags then you could treat this like like an array. the first song being in position 0  				
				_currentArrayNum = 0; 
				//this var helps keep track of where you are in the array when you click next or previous.
				
				
				_soundObj = new Sound(); 
				_soundObj.load(new URLRequest(_xmlObj..songURL[_currentArrayNum])); 
				
				_soundChannel = new SoundChannel(); 
				_soundTransform = new SoundTransform(); 
				
				VSlider.snapInterval =.1; 
				VSlider.addEventListener(Event.CHANGE, ChangeVolume); 				
			} 
			
			private function playSound():void 
			{ 
				_soundChannel = _soundObj.play(); 
				_isPlayingSound = true; 
				_soundTransform.volume = .5; 
				_soundChannel.soundTransform = _soundTransform;                
			} 
			
			private function pauseSound():void 
			{ 
				if(_isPlayingSound == true){ 
					//保存播放的点
					_currentSndPosition = _soundChannel.position; 
					trace("_currentSndPosition = " + _currentSndPosition); 
					_isPlayingSound = false; 
					_soundChannel.stop(); 
				}else{
					//从上次断点开始播放
					_soundChannel = _soundObj.play(_currentSndPosition); 
					_isPlayingSound = true; 
					trace("_currentSndPosition = " + _currentSndPosition); 
				} 
			} 
			
			//if your var's value is not yet the equal fo the highest number in your songURL array. then add 1 and load the next 
			//the opposite is true going backwards 
			private function nextSound():void 
			{ 
				trace(_currentArrayNum+"   "+_xmlObj..songURL.length()) ;
				if(_currentArrayNum != _xmlObj..songURL.length()){ 
					
					_currentArrayNum ++; 
					_soundObj.load(new URLRequest(_xmlObj.songURL[_currentArrayNum])); 
					playSound();
				} 
			} 
			
			private function prevSound():void 
			{ 
				if(_currentArrayNum !=0){ 
					
					_currentArrayNum --; 
					_soundObj.load(new URLRequest(_xmlObj..songURL[_currentArrayNum])); 
					playSound();
				} 
			} 
			
			//the slider has a min value of 0 and a max value of 1 and will snap to each position in between (.1) 
			//what ever that number is in between 0 and 1 is the new volume 
			private function ChangeVolume(evt:Event):void{ 
				_soundTransform.volume = evt.target.value; 
				_soundChannel.soundTransform = _soundTransform; 
				trace(evt.target.value); 
			} 
		]]> 
	</fx:Script> 
	<s:Label text="MP3播放器" />
	<s:HGroup> 			
		<s:Button label="Play" click="playSound();"/> 
		<s:Button label="Pause" click="pauseSound();"/> 
		<s:Button label="Next" click="nextSound();"/> 
		<s:Button label="Previous" click="prevSound()"/> 
		<s:HSlider id="VSlider" minimum="0" maximum="1" /> 
		
	</s:HGroup> 
	
</s:Application>