微软的Microsoft.Xna.Framework.Media组件中自带有MediaPlayer的库，其中库里面存放有三首曲子，我们可以通过引用该组件来调用库中相应的函数进行歌曲播放，通过引用Microsoft.Xna.Framework.dll，引用该命名空间即可使用该 组件。
如上图，有四个控件，一个图片控件，一个文本控件，两个控制按钮。当页面被导航进来时，得到一个Song类型的歌曲，并为文本控件赋值歌曲名称。得到类型后，在页面初始完成时，得到一张歌曲的封面并为图片控件赋值。下面是整个应的代码：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using Microsoft.Phone.Controls;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Media;
using System.Windows.Threading;
using System.IO;
using System.Windows.Resources;
using System.Windows.Media.Imaging;namespace PostCodeManager
{
public partial class MainPage : PhoneApplicationPage
{
#region 成员声明
Song _playSong; //声明一个Song 类型的变量
bool _historyItemLaunch;
const String _playSongKey = "playSong";
#endregion// Constructor
public MainPage()
{
InitializeComponent();
_playSong = null;
_historyItemLaunch = false;//声明一个Timer 使用线程运行 XNA internals 来自于微软XNA框架
DispatcherTimer dt = new DispatcherTimer();
dt.Interval = TimeSpan.FromMilliseconds(33);
//使用委托调用逐帧调用 FrameworkDispatcher.Update();
dt.Tick += delegate
{
try
{
// 这个函数作用是更新各种XNA组件状态，并触发相应的事件,这个是必须的，否则会报异常
FrameworkDispatcher.Update();
}
catch
{
throw;
}
};
dt.Start();+= new EventHandler<EventArgs>(MediaPlayer_MediaStateChanged);
}/// <summary>
/// 当页面进入时调用
/// </summary>
/// <param name="e"></param>
protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
{
MediaLibrary library = new MediaLibrary();
if (NavigationContext.QueryString.ContainsKey(_playSongKey))
{
String songToPlay = NavigationContext.QueryString[_playSongKey];
foreach (Song song in library.Songs)
{
if (0==String.Compare(songToPlay,song.Name))
{
_playSong = song;
}
}
_historyItemLaunch = true;
}
else if (MediaPlayer.State==MediaState.Playing)
{
_playSong = MediaPlayer.Queue.ActiveSong;
}
else
{
Random rd = new Random();
if (library.Songs.Count>0)
{
_playSong = library.Songs[rd.Next(library.Songs.Count)];
}
else
{
SongName.Text = "no songs in library";
btn_play_music.IsEnabled = false;
}
}base.OnNavigatedTo(e);
}void MediaPlayer_MediaStateChanged(object sender, EventArgs e)
{
switch (MediaPlayer.State)
{
case MediaState.Playing:
btn_play_music.IsEnabled = false;
btn_stop.IsEnabled = true;
break;
case MediaState.Paused:
case MediaState.Stopped:
btn_play_music.IsEnabled = true;
btn_stop.IsEnabled = false;
break;
}
}/// <summary>
/// 为主窗体添加UI加载完成后的事件
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void PhoneApplicationPage_Loaded(object sender, RoutedEventArgs e)
{
PopulateSongMetaData();
setInitialButtonState();
if (_historyItemLaunch)
{
playSong();
}
}
/// <summary>
/// 开始播放音乐
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void btn_play_music_Click(object sender, RoutedEventArgs e)
{
playSong();
}/// <summary>
/// 停止播放音乐
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void btn_stop_Click(object sender, RoutedEventArgs e)
{
stopSong();
}/// <summary>
/// 播放
/// </summary>
private void playSong()
{
if (_playSong!=null)
{
MediaPlayer.Play(_playSong);
}
}
/// <summary>
/// 停止
/// </summary>
private void stopSong()
{
if (MediaState.Playing==MediaPlayer.State)
{
MediaPlayer.Stop();
}
}/// <summary>
/// 使用图片读取图片封面
/// </summary>
private void PopulateSongMetaData()
{
if (_playSong!=null)
{
SongName.Text = _playSong.Name;
Stream albumArtStream = _playSong.Album.GetAlbumArt();
if (albumArtStream==null)
{
StreamResourceInfo albumArtPlaceholder = Application.GetResourceStream(new Uri("ApplicationIcon.png", UriKind.Relative));
albumArtStream = albumArtPlaceholder.Stream;
}
BitmapImage albumArtImage = new BitmapImage();
albumArtImage.SetSource(albumArtStream);
cover.Source = albumArtImage;
}
}/// <summary>
/// 初始化按钮
/// </summary>
private void setInitialButtonState()
{
switch (MediaPlayer.State)
{case MediaState.Playing:
btn_play_music.IsEnabled = false;
btn_stop.IsEnabled = true;
break;
case MediaState.Paused:
case MediaState.Stopped:
btn_play_music.IsEnabled = true;
btn_stop.IsEnabled = false;
break;
}
}
MediaPlayer.MediaStateChanged ;
}
}
TIP：OnNavigatedTo方法是一个重写系统事件的方法，此方法以检查导航请求并且准备供显示的页面，为一些必要的组件和处理逻辑提供处理任务，上一篇提到过工程里面包含有一张图片为SplashScreenImage.jpg，这张图片就是就是为处理方法提供的临时页面。这个做法好处在于，用户会认为程序启动时和启动后都是一致的，当我们真正程序启动完成
后，要做一些页面其他的加载，就可以在pageLoad 里面处理。下面为了证实我所说的，来调试一下吧，首先我们在OnNavigatedTo
的入口处加一个断点，按F5进入调试模式，我们来看看程序是怎么跑的。