Полезная информация

Java AWT

Previous Chapter 14
And Then There Were Applets
Next
 

14.2 AudioClip Interface

Once an audio file is loaded into memory with getAudioClip(), you use the AudioClip interface to work with it. Methods

Three methods define the AudioClip interface. The class that implements these methods depends on the run-time environment; the class is probably sun.applet.AppletAudioClip or netscape.applet.AppletAudioClip.

If you play an audio clip anywhere within your Applet, you should call the AudioClip stop() method within the stop() method of the applet. This ensures that the audio file will stop playing when the user leaves your web page. Stopping audio clips is a must if you call loop() to play the sound continuously; if you don't stop an audio clip, the user will have to exit the browser to get the sound to stop playing.

Applets can play audio clips simultaneously. Based upon the user's actions, you may want to play a sound file in the background continuously, while playing other files.

void play ()

The play() method plays the audio clip once from the beginning.

void loop ()

The loop() method plays the audio clip continuously. When it gets to the end-of-file marker, it resets itself to the beginning.

void stop ()

The stop() method stops the applet from playing the audio clip.

Using an AudioClip

The applet in Example 14.2 loads three audio files in the init() method. The start() method plays Dino barking in the background as a continuous loop. Whenever the browser calls paint(), Fred yells "Wilma," and when you click the mouse anywhere, the call to mouseDown() plays Fred yelling, "Yabba-Dabba-Doo." If you try real hard, all three can play at once. Before playing any audio clip, the applet makes sure that the clip is not null--that is, that the clip loaded correctly. stop() stops all clips from playing; you should make sure that applets stop all audio clips before the viewer leaves the web page.

Example 14.2: AudioClip Usage

import java.net.*;
import java.awt.*;
import java.applet.*;
public class AudioTestExample extends Applet{
    AudioClip audio1, audio2, audio3;
    public void init () {
        audio1 = getAudioClip (getCodeBase(), "audio/flintstones.au");
        audio2 = getAudioClip (getCodeBase(), "audio/dino.au");
        audio3 = getAudioClip (getCodeBase(), "audio/wilma.au");
    }
    public boolean mouseDown (Event e, int x, int y) {
        if (audio1 != null)
            audio1.play();
        return true;
    }
    public void start () {
        if (audio2 != null)
            audio2.loop();
    }
    public void paint (Graphics g) {
        if (audio3 != null)
            audio3.play();
    }
    public void stop () {
        if (audio1 != null)
            audio1.stop();
        if (audio2 != null)
            audio2.stop();
        if (audio3 != null)
            audio3.stop();
    }
}


Previous Home Next
What's a Java Applet? Book Index AppletContext Interface

Java in a Nutshell Java Language Reference Java AWT Java Fundamental Classes Exploring Java