打造.Net Framework3.0 下的Media Player

*基本要求：安装了.NET Framework 3.0 beta版（我用的是beta3)

下载Demo


 

我打算学着做一个MP3 Player玩一下，虽然在.Net Famework 2.0 的System.Media命名空间有一个可以播放声音的类SoundPlayer，然而它只支持播放*.wav波形文件，而我需要的是可以播放*.mp3文件。于是在网搜了一下，结果基本上都是用“Windows Media Player”这一COM组件

于是我又在Microsoft Visual Studio 2005 文档中搜了一下“MediaPlayer”，以期上面有对这一组件的说明，结果意外地发现在.Net Framework 3.0中竟然就有“MediaPlayer”这个类，一看名字就猜测它能够满足我的需求，最后证明的确如此。于是我立即动手写了一个Demo，学习一下这个类的使用。

MediaPlayer处于System.Windows.Media命名空间下，与PresentationCore.dll、PresentationFramework.dll以及WindowsBase.dll三个在.Net Framwork 3.0中新加入的三个动态链接库相关联。好了，那就让我们开始吧！

先新建一个Window应用程序，然后添加对以上3个动态链接库的引用，最后再加一条“using System.Windows.Media;”添加MediaPlayer的命名空间。你就可以在你的应用程序中使用MediaPlayer这个类了。

当然，你也可以直接新建一个WinFx Windows Application，它会自动完成对动态链接库和命名空间的引用，然后删除xaml文件，因为在我的这个Demo里只是想试用一下MediaPlay这个类，不需要用到xaml，再添加一个Windows窗体即可（当然还要手工添加Main函数）。

至此该Demo的应用程序框架已经搭建好了，只剩下在它上面添砖加瓦了，也就是尝试着使用MediaPlayer的各种属性和方法了。

以下是,NET Framwork 3.0 Development   －>   Class Library 中列出的该类的全部属性和方法：

Provides media playback for drawings.

The following tables list the members exposed by the MediaPlayer type.

Public Constructors

	Name	Description
	MediaPlayer	Initializes a new instance of the MediaPlayer class.

Public Properties

	Name	Description
	Balance	Gets or sets the balance between the left and right speaker volumes.
	BufferingProgress	Gets the percentage of buffering completed for streaming content.
	CanFreeze	Gets a value that indicates whether this object can be made unmodifiable. (inherited from Freezable)
	CanPause	Gets a value indicating whether the media can be paused.
	Clock	Gets or sets the MediaClock associated with the MediaTimeline to be played.
	DependencyObjectType	Gets the type that represents the common language runtime (CLR) type of this instance. (inherited from DependencyObject)
	Dispatcher	Gets the Dispatcher this DispatcherObject is associated with. (inherited from DispatcherObject)
	DownloadProgress	Gets the percentage of download progress for content located at a remote server.
	HasAnimatedProperties	Returns true if any properties on this DependencyObject have a persistent animation or the object has one or more clocks associated with any of its properties. (inherited from Animatable)
	HasAudio	Gets a value that indicating whether the media has audio output.
	HasVideo	Gets a value that indicates whether the media has video output.
	IsBuffering	Gets a value that indicates whether the media is buffering.
	IsFrozen	Gets a value that indicates whether the object is currently modifiable. (inherited from Freezable)
	IsMuted	Gets a value that indicates whether the media is muted.
	IsSealed	Gets a value that declares whether this instance is currently read-only.(inherited from DependencyObject)
	NaturalDuration	Gets the natural duration of the media.
	NaturalVideoHeight	Gets the pixel height of the video.
	NaturalVideoWidth	Gets the pixel width of the video.
	Position	Gets or sets the current position of the media.
	ScrubbingEnabled
	Source	Gets the media Uri.
	SpeedRatio	Gets or sets the ratio of speed that media is played at.
	Volume	Gets or sets the media's volume.

Public Methods (see also Protected Methods )

	Name	Description
	ApplyAnimationClock	Overloaded. Animates the specified DependencyProperty using the specified AnimationClock. (inherited from Animatable)
	BeginAnimation	Overloaded. Applies an animation to the specified DependencyProperty. (inherited from Animatable)
	CheckAccess	Determines whether the calling thread has access to this DispatcherObject. (inherited from DispatcherObject)
	ClearValue	Overloaded. Clears the local value of a property. (inherited from DependencyObject)
	Clone	Returns a modifiable copy of this instance. (inherited from Animatable)
	CloneCurrentValue	Creates a modifiable clone of this Freezable, making deep copies of this object's current values. (inherited from Freezable)
	Close
	CoerceValue	Invokes any CoerceValueCallback function that was declared when this dependency property was registered. This same callback will be called internally whenever that property on a DependencyObject changes its value. (inherited from DependencyObject)
	Equals	Overloaded. (inherited from DependencyObject)
	Freeze	Overloaded. Makes a Freezable unmodifiable and sets its IsFrozen property to true, or determines whether the specified Freezable can be made unmodifiable. (inherited from Freezable)
	GetAnimationBaseValue	Returns the non-animated value of the specified DependencyProperty. (inherited from Animatable)
	GetAsFrozen	Creates a frozen copy of this Freezable , using base (non-animated, non-databound) property values. Because the copy is frozen, any frozen sub-objects are copied by reference. (inherited from Freezable)
	GetCurrentValueAsFrozen	Creates a frozen copy of this Freezable , using current property values. Because the copy is frozen, any frozen sub-objects are copied by reference. (inherited from Freezable)
	GetHashCode	(inherited from DependencyObject)
	GetLocalValueEnumerator	Creates a specialized enumerator for determining which dependency properties have locally set values on this DependencyObject. (inherited from DependencyObject)
	GetType	Gets the Type of the current instance. (inherited from Object)
	GetValue	Returns the current effective value of a dependency property on this DependencyObject. (inherited from DependencyObject)
	InvalidateProperty	Invalidates the preexisting value of the specified dependency property. (inherited from DependencyObject)
	Open	Opens the given Uri for media playback.
	Pause	Pauses media playback.
	Play	Plays media from the current Position.
	ReadLocalValue	Returns the local value of a dependency property, if it exists. (inherited from DependencyObject)
	ReferenceEquals	Determines whether the specified Object instances are the same instance. (inherited from Object)
	SetValue	Overloaded. Sets the local value of a dependency property. (inherited from DependencyObject)
	ShouldSerializeStoredWeakReference	(inherited from Animatable)
	Stop	Stops media playback.
	ToString	Returns a String that represents the current Object. (inherited from Object)
	VerifyAccess	Determines whether the calling thread has access to this DispatcherObject. (inherited from DispatcherObject)

Protected Methods

	Name	Description
	CloneCore	Overridden.
	CloneCurrentValueCore	Overridden.
	CreateInstance	Initializes a new instance of the Freezable class. (inherited from Freezable)
	CreateInstanceCore	Overridden.
	Finalize	Allows an Object to attempt to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (inherited from Object)
	Freeze	Overloaded. Makes a Freezable unmodifiable and sets its IsFrozen property to true, or determines whether the specified Freezable can be made unmodifiable. (inherited from Freezable)
	FreezeCore	An Animatable will return false from this method if there are any Clocks animating any of its properties. If the Animatable has persistent animations specified, but all of the Clocks have been removed, it may still return true from this method if the Timelines themselves can be frozen. (inherited from Animatable)
	GetAsFrozenCore	Overridden.
	GetCurrentValueAsFrozenCore	Implements GetCurrentValueAsFrozen behavior in Freezable derived classes. (inherited from Freezable)
	MemberwiseClone	Creates a shallow copy of the current Object. (inherited from Object)
	OnChanged	Called when the current Freezable object is modified. (inherited from Freezable)
	OnFreezablePropertyChanged	Overloaded. (inherited from Freezable)
	OnPropertyChanged	Overrides the DependencyObject implementation of OnPropertyChanged in order to also invoke any Changed handlers in response to a dependency property of type Freezable changing. (inherited from Freezable)
	ReadPreamble
	ShouldSerializeProperty	Returns a value that indicates whether serialization processes should serialize the values for the given dependency property. (inherited from DependencyObject)
	WritePostscript	Invokes the OnChanged method on this Freezable. (inherited from Freezable)
	WritePreamble

Public Events

	Name	Description
	BufferingEnded	Occurs when buffering has finished.
	BufferingStarted	Occurs when buffering has started.
	Changed	Occurs when the current object is modified. (inherited from Freezable)
	MediaEnded	Occurs when the media has finished playback.
	MediaFailed	Occurs when an error is encountered
	MediaOpened	Occurs when the media is opened.
	ScriptCommand	Occurs when a script command has been encountered within the media.

这些相信不用我翻译就应该看得懂吧，从属性可以知道它不仅支持音频文件，还支持视频文件（其实从类名就可以看出来）。在这些属性中，最重要的有：

Source属性：

public Uri Source { get; }

IsMuted属性：可以设置静音

Volume属性：The media's volume represented on a linear scale between 0 and 1. The default is 0.5.

Position属性：

public TimeSpan Position { get; set; }

SpeedRatio属性：The ratio of speed that media is played back represented by a value
between 0 and the largest double value. The default is 1.0.

 

 

最重要的方法当然就是Open、Play、Pause、Stop这四个方法了。

有了这此属性和方法，你不需要WMPlayer组件就可以打造一个属于你自己的MP3 Player了。