Java How to Program Fourth Edition - DCC

Chapter 22 Java Media Framework and Java Sound (on CD) 1281
122 // if replay set, replay forever
123 else
124
125 if ( lineEvent.getType() == LineEvent.Type.STOP &&
126 replay ) {
127
128 System.out.println( "replay" );
129
130 // replay clip forever
131 clip.loop( Clip.LOOP_CONTINUOUSLY );
132 }
133 }
134
135 // set replay of clip
136 public void setReplay( boolean value )
137 {
138 replay = value;
139 }
140
141 // stop and close clip, returning system resources
142 public void close()
143 {
144 if ( clip != null ) {
145 clip.stop();
146 clip.close();
147 }
148 }
149
150 } // end class ClipPlayer
Fig. Fig. 22.5 22.5 ClipPlayer plays an audio file (part 4 of 4).
All Lines generate LineEvents, which can be handled by LineListeners.
LineEvents occur when starting, stopping, playing and closing a Line object. Although
a Line stops playback automatically when it reaches the end of an audio file, class Clip-
Player implements interface LineListener (line 10) and can close the Clip permanently
or replay the Clip (discussed shortly). LineListeners are useful for tasks that
must be synchronized with the LineEvent states of a line.
The Clip reads audio data from an AudioInputStream (a subclass of Input-
Stream), which provides access to the stream’s data content. This example loads clips of
the audio data before attempting to play it, and therefore is able to determine the length of
the clip in frames. Each frame represents data at a specific time interval in the audio file.
To play sampled audio files using Java Sound, a program must obtain an AudioInput-
Stream from an audio file, obtain a formatted Clip line, load the AudioInput-
Stream into the Clip line and start the data flow in the Clip line.
To play back sampled audio, the audio stream must be obtained from an audio file.
ClipPlayer method openFile (lines 31–54) obtains audio from soundFile (initialized
in the ClipPlayer constructor at lines 25–28). Lines 35–36 call AudioSystem
static method getAudioInputStream to obtain an AudioInputStream for
soundFile. Class AudioSystem facilitates access to many of the resources needed to
play and manipulate sound files. Method getAudioInputStream throws an Unsup-