Solving Common Sound Problems - Java Tutorial 5.0 英文版

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Trail: Sound

Solving Common Sound Problems

Problem: How can I have a WAV or MP3 file play when an image on my Web page is clicked?

To have a sound play when an image is clicked, your picture must be contained in a component that registers mouse events. The following sample adds a GIF to an ImageIcon and adds the ImageIcon to a JButton. When you press the button, a WAV file is played. The SoundApplet code was modified to only contain this button. The resulting applet is called PictButton. Here are the files you will need:

PictButton.java

AppletSoundList.java

AppletSoundLoader.java (to load the sound)

Sample image and sample sound: rocketship.gif and bottle-open.wav.

Sample HTML page: PictButton.html

Problem: Does the Java Platform support audio recording?

Java 2 (JDK 1.2) does not include support for audio recording. This functionality will be provided through the Java Sound API and the Java Media Framework (JMF) 2.0 API. The Java Sound API and a preliminary implementation will be available soon. The JMF 2.0 API is currently available for public review. For more information, see the Java Media web pages.
Java Sound: http://java.sun.com/products/java-media/sound/
Java Media Framework: http://java.sun.com/products/java-media/jmf/

Problem: Is there a way to play a WAV file that does not have an URL?
If you have a file on your system, you can use the code in the tutorial to generate the URL. All that you need to do is:
Make sure that your WAV file and code are in the same directory.
If you are running an applet, add the name of your sound to SoundApplet.java like this (otherwise, add it to SoundApplication.java):
   
        String wavFile = "bottle-open.wav";   
If you look at SoundApplet.java or SoundApplication.java, you will see the names of our sound files listed in this way near the top of the code.
Make sure that you have SoundApplet.java, AppletSoundList.java and AppletSoundLoader.java and be sure that you compile them together like this:
   
     	javac *java
If you are running an application, make sure that you have SoundApplication.java, SoundList.java, and SoundLoader.java
The URL is generated by the code with the filename that you give it. If you are running the applet code, the base URL is retrieved with getCodeBase(). The base URL is basically the path indicating where your file is located. For example, if your file is located at /mymachine/java/samples/sound then this would be your base URL.
If you are running the application code, the base URL is retrieved with System.getProperty("user.dir"). In both cases, the filename is attached to the base URL while using the startLoading method. You can see an example of this in SoundApplet.java and SoundApplication.java in the method startLoadingSounds().
Problem: I want to play several sound files in succession from an applet. However, when I use play two times after each other they just get mixed up.

Unfortunately, the Java 2 SDK does not provide notification of when playback has completed. The Java Sound API provides this feature. It is available as an early access release. If you must use the SDK, you could try to determine the length of each clip and sleep for the same about of time before playing the next clip.

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