Swing Hacks

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Chapter 10, Audio

#72 Play a Sound with Java Media Framework

HACK

The major change from the CoreJavaSound demo is in the constructor, after

the dialog is readied. You create a

MediaLocator, a sort of generic means of

referring to the source location of media, from a URL of the selected file.

The

MediaLocator allows you to create a Player with a one-line call to

Manager.createRealizedPlayer(MediaLocator). A lot occurs in this call: the

Manager, a sort of central point of access to JMF resources, creates a Player,

wires it up to the

MediaLocator, calls prefetch( ) to process some of the

media data (to reduce startup delay), and calls

realize( ) to allocate system-

dependent media resources. The result is a ready-to-play

Player.

To add event-awareness, add a listener with

addControllerListener( ),

Controller being a superclass of Player. Finally, you can play the media with

start( ).

The

ControllerListener interface defines a single method, controllerUpdate(),

which receives a

ControllerEvent. In JMF, the class of the event is used for

determining behavior; there are more than a dozen you might choose to deal

with. To get the “end of the media” event, you just check to see if the event

is an

EndOfMediaEvent object, which in this case is handled by hiding the dia-

log and quitting the application.

Take JMF for a Spin

Functionally, the application is largely identical to the CoreJavaSound demo:

a

JFileChooser asks you to pick a file. When you do, it starts playing and a

dialog box shows you the filename. When the audio completes, the applica-

tion quits.

player.addControllerListener (this);

player.prefetch( );

player.start( );

playingDialog.setVisible(true);

}

// ControllerListener implementation

public void controllerUpdate (ControllerEvent e) {

System.out.println (e.getClass().getName( ));

if (e instanceof EndOfMediaEvent) {

playingDialog.setVisible(false);

System.exit (0);

}

}

}

Example 10-4. Playing audio with Java Media Framework (continued)