📅 最后修改于: 2020-10-14 07:26:10 🧑 作者: Mango
需要时，现代世界的富Internet应用程序必须能够播放和编辑媒体文件。 JavaFX提供了丰富的媒体API，可以根据用户需求播放音频和视频。
JavaFX Media API使用户可以将音频和视频合并到富互联网应用程序(RIA)中。 JavaFX媒体API可以在电视，移动设备，平板电脑等不同设备上分发媒体内容。
在本教程的这一部分中，我们将讨论JavaFX以交互方式处理媒体文件的功能。为此，JavaFX提供了包含所有必需类的包javafx.scene.media。 javafx.scene.media包含以下类。
JavaFX团队已将媒体API设计为事件驱动的。媒体函数附带的回调行为用于处理媒体事件。代替通过EventHandler为按钮键入代码，而是实现了一种代码，该代码响应媒体播放器的OnXXXX事件的触发，其中XXXX是事件名称。
java.lang.Runnable功能接口用作遇到事件时调用的回调。在javafx中播放媒体内容时，我们将创建要在onReady事件上设置的Lambda表达式(java.lang.Runnable接口)。考虑以下示例。
Media media = new Media(url);
MediaPlayer mediaPlayer = new MediaPlayer(media);
Runnable playMusic = () -> mediaPlayer.play();
mediaPlayer.setOnReady(playMusic);
playMusic变量被分配给lambda表达式。这被传递到媒体播放器的setOnReady()方法中。遇到onReady事件时，将调用Lambda表达式。
下表讨论了可能的媒体和媒体播放器事件。
| Class | Set On Method | Description |
|---|---|---|
| Media | setOnError() | This method is invoked when an error occurs. It is the part of the class Media. |
| MediaPlayer | setOnEndOfMedia() | The method is invoked when end of the media play is reached. |
| MediaPlayer | setOnError() | This method is invoked when an error occurs. |
| MediaPlayer | setOnHalted() | This method is invoked when the status of media changes to halted. |
| MediaPlayer | setOnMarker() | This method is invoked when the Marker event is triggered. |
| MediaPlayer | setOnPaused() | This method is invoked when a pause event occurs. |
| MediaPlayer | setOnPlaying() | This method is invoked when the play event occurs. |
| MediaPlayer | setOnReady() | This method is invoked when the media is in ready state. |
| MediaPlayer | setOnRepeat() | This method is invoked when the repeat property is set. |
| MediaPlayer | setOnStalled() | This method is invoked when the media player is stalled. |
| MediaPlayer | setOnStopped() | This method is invoked when the media player has stopped. |
| MediaView | setOnError() | This method is invoked when an error occurs in the media view. |
我们必须注意，MediaPlayer类包含最多触发的事件，而MediaView和Media类各自包含一个事件。
下表描述了该类的属性。除onError外，所有属性均为只读。
| Property | Description |
|---|---|
| duration | The duration of the source media in seconds. This property is of object type of the class Duration. |
| error | This is a property set to media exception value when an error occurs. This property is of the type object of the class MediaException. |
| height | The height of the source media in pixels. This is an integer type property. |
| onError | The event handler which is called when the error occurs. The method setOnError() is used to set this property. |
| width | The width of the source media in pixels. This is an integer type property |
表中只有一个构造函数。
public Media(java.lang.String source)：它使用指定的源文件实例化Media类。
下表描述了该类的属性以及setter方法。
| Property | Property | Setter Methods |
|---|---|---|
| audioSpectrumInterval | This is a double type property. It indicates the interval between the spectrum updates in seconds. | setAudioSpectrumInterval (double value) |
| audioSpectrumListener | This is an object type property of the class AudioSpectrumListener. It indicates the audiospectrumlistener for an audio spectrum. | setAudioSpectrumListener(AudioSpectrumListener listener) |
| audioSpectrumNumBands | This is an integer type property. It indicates the number of bands between the audio spectrum. | setAudioSpectrumNumBands(int value) |
| audioSpectrumThreshold | This is an integer type property. It indicates the sensitivity threshold | setAudioSpectrumThreshold(int value) |
| autoPlay | This is the boolean type property. The true value indicates the playing will be started as soon as possible. | setAutoPlay(Boolean value) |
| balance | This is a double type property. It indicates the balance of the audio output. | setBalance(double value) |
| bufferProgressTime | This is an object type property of the class Duration. It indicates the duration of the media which can be played without stalling the media-player. | Can not be set as it is read only property. |
| currentCount | This is read only integer type property. It indicates the number of completed playback cycles. | Can not be set as it is read only property. |
| currentRate | This is a double type property. It indicates the current rate of the playback. It is read only property. | Can not be set as it is read only property. |
| currentTime | This is an object type property of the class Duration. It indicates the current media playback time. | Can not be set as it is read only property. |
| cycleCount | It is the integer type property. It indicates the number of times, the media will be played. | setCycleCount(int value) |
| cycleDuration | It is the ready only property. It is of the type object of the class Duration. It indicates the amount of time between the start time and stop time of the media. | Can not be set as it is read only property. |
| error | It is a read only property. It is an object type property of the class MediaException. It is set to a Media-Exception if an error occurs. | Can not be set as it is read only property. |
| mute | It is a boolean type property. It indicates whether the audio is muted or not. | SetMute(boolean value) |
| onEndOfMedia | It is an object type property of the interface Runnable. It is set to an Event Handler which will be invoked when the end of the media file is reached. | setOnEndOfMedia(java.lang.Runnable value) |
| onError | It is an object type property of the interface Runnable. It indicates the Event Handler which will be invoked when the status changes to halted. | setOnHalted(java.lang.Runnable value) |
| onMarker | It is an object type property of the class MediaMarkerEvent. It indicates the EventHandler which will be invoked when the current time reaches the media marker. | setOnMarker(EventHandler |
| onPaused | It is an object type property of the interface Runnable. It indicates the EventHandler which will be invoked when the status changed to paused. | setOnPaused(java.lang.Runnable value) |
| onPlaying | It is an object type property of the interface Runnable. It indicates the EventHandler which will be invoked when the status changed to playing. | setOnPlaying(java.lang.Runnable value) |
| onReady | It is an object type property of the interface Runnable. It indicates the EventHandler which will be invoked when the status changed to Ready. | setOnReady(java.lang.Runnable value) |
| onRepeat | It is an object type property of the class MediaMarkerEvent. It indicates the EventHandler which will be invoked when the current time reaches the stop time and will be repeating. | setOnRepeat(java.lang.Runnable value) |
| onStalled | It is an object type property of the interface Runnable. It indicates the Event Handler which will be invoked when the status changed to Stalled. | setOnStalled(java.lang.Runnable value) |
| onStopped | It is an object type property of the interface Runnable. It indicates the EventHandler which will be invoked when the status changed to Stopped. | setOnStopped(java.lang.Runnable value) |
| rate | It is the double type property. It indicates the rate at which the media should be played. | setRate(double value) |
| startTime | This property is of the type object of the class Duration. It indicates the time where media should start playing. | setStartTime(Duration value) |
| status | This is the read only property. It indicates the current state of the Media player. | Can not be set as it is read only property. |
| stopTime | This property is an object type of the class Duration. It indicates the time offset where the media should stop playing. | setStopTime(double value) |
| totalDuration | It is an object type property of the class Duration. It indicates the total time during which the media should be played. | Can not be set as it is read only property. |
| volume | It is a double type property. It indicates the volume at which the media should be playing. | setVolume(double value) |
该类仅包含一个构造函数，如下所示。
public MediaPlayer (Media media)