Swing Hacks

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Chapter 10, Audio

#71 Play a Sound with JavaSound

HACK

Realistically, you actually need to host the applet (HTML and code) on a

web server and access it via a URL. If you have access to a web server, put

index.html and AppletAudio.class in their own web directory, along with

some known-to-work audio files, then access it remotely with a browser.

Type in a URL to one of those audio files by hand and try to load it. This

time, it should work (finally).

But what formats are supported? Back in Java 1.0 and 1.1,

AudioClips had to

be encoded in mono at 8,000 Hz with µ-law encoding…which was pretty

awful. In Java 1.4.2, a few simple container formats are supported. AIFF and

WAV both work, but Mac OS X doesn’t support the .au format, which used

to be the only option (Windows can play .au, by the way). Also,

AudioClip

can’t play WAVs and AIFFs whose contents are compressed in any way.

And neither Mac nor Windows supports MP3 as

AudioClips.

You can also load audio from sites other than the one hosting your applet,

which seems contrary to the stringent applet security seen earlier.

So, using

java.awt.applet’s AudioClip means your application has to be an

applet, it can only run a handful of audio formats, and your media can’t be

local unless you go through the hassle of overriding the

SecurityManager for

the applet.

As you might imagine, early Java developers demanded a replacement.

H A C K

#71

Play a Sound with JavaSound Hack #71

Get a small clip to play from memory with a lot less hassle.

The JavaSound API was developed to answer complaints about the inade-

quacies of the

AudioClip class in the applet package…not the least of which

was the fact that it couldn’t be used in applications. JavaSound consists of

two packages—

javax.sound.sampled and javax.sound.midi—plus two ser-

vice provider interface (

spi) sub-packages for adding support for new

devices, formats, converters, etc.

JavaSound was introduced as an extension to Java 1.2 (I know, I know,

“Java 2 Standard Edition, version 1.2”), and it became part of Core Java in

1.3. In other words, you’re pretty safe assuming that it’s present on your

user’s machine. That’s one big point in its favor.

Putting JavaSound to Work

To show off JavaSound, the code in Example 10-3 exhibits a short applica-

tion that allows the user to pick a file from the local filesystem and play it. A

Play a Sound with JavaSound #71

Chapter 10, Audio

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365

HACK

dialog shows the selected filename; OK it when the audio completes to exit

the program.

Example 10-3. Playing audio with JavaSound

public class CoreJavaSound extends Object

implements LineListener {

File soundFile;

JDialog playingDialog;

Clip clip;

public static void main (String[] args) {

JFileChooser chooser = new JFileChooser( );

chooser.showOpenDialog(null);

File f = chooser.getSelectedFile( );

try {

CoreJavaSound s = new CoreJavaSound (f);

} catch (Exception e) {

e.printStackTrace( );

}

}

public CoreJavaSound (File f)

throws LineUnavailableException, IOException,

UnsupportedAudioFileException {

soundFile = f;

// prepare a dialog to display while playing

JOptionPane pane = new JOptionPane ("Playing " + f.getName( ),

JOptionPane.PLAIN_MESSAGE);

playingDialog = pane.createDialog (null, "Application Sound");

playingDialog.pack( );

// get and play sound

Line.Info linfo = new Line.Info (Clip.class);

Line line = AudioSystem.getLine (linfo);

clip = (Clip) line;

clip.addLineListener (this);

AudioInputStream ais = AudioSystem.getAudioInputStream(soundFile);

clip.open (ais);

clip.start( );

}

// LineListener

public void update (LineEvent le) {

LineEvent.Type type = le.getType( );

if (type == LineEvent.Type.OPEN) {

System.out.println ("OPEN");

} else if (type == LineEvent.Type.CLOSE) {

System.out.println ("CLOSE");

System.exit (0);