Loading SoundPool with audio from APK Expansion file

问题

In the documentation it says:

If you're using your expansion files to store media files, a ZIP file still allows you to use Android media playback calls that provide offset and length controls (such as MediaPlayer.setDataSource() and SoundPool.load()).

I have 10 small .ogg files and I want to use SoundPool.load (FileDescriptor fd, long offset, long length, int priority) to load these audio files. I've written some code, but when I run it I get error message:

"Unable to load sample: (null)"

, and obviously the audio isn't played. Here is what I attempted:

public class MainActivity extends Activity {

    SoundPool sounds;
    boolean loaded = false;
    int streamID;
    int  theId;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        System.gc();
        setContentView(R.layout.activity_main);
        sounds = new SoundPool(10, AudioManager.STREAM_MUSIC,0);
        sounds.setOnLoadCompleteListener(new SoundPool.OnLoadCompleteListener() {
            @Override
            public void onLoadComplete(SoundPool sp, int sid, int status) {
                loaded = true;
        }});
        loadSounds();
        playSound(theID);
    }

    private void loadSounds() {
        AssetFileDescriptor descriptor = null;
        try {
            descriptor = getFileDescriptor(this, "audio_files/end_credits.ogg");
        } catch (Exception e) {
        } finally {
            if (descriptor != null)
                try{descriptor.close();} catch (IOException e) {}
        }
    theId =   sounds.load(descriptor.getFileDescriptor(), descriptor.getStartOffset(), descriptor.getLength(), 1);
}
    public static AssetFileDescriptor getFileDescriptor(Context ctx, String path) {
        AssetFileDescriptor descriptor = null;
        try {
            ZipResourceFile zip = APKExpansionSupport.getAPKExpansionZipFile(ctx, 4, -1);
            descriptor = zip.getAssetFileDescriptor(path);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return descriptor;
    }
    private void playSound(int soundID){
        if(loaded){
            streamID = sounds.play(soundID, 1, 1, 1, 0, 1);}
    }
}

回答1:

Ok, seems like the reason is audio isn't loading fast enough. I put playSound(theID); right after loadSounds(); whereas it needs couple seconds to load before it can be played. But the code is working up to that point.

来源：https://stackoverflow.com/questions/21299892/loading-soundpool-with-audio-from-apk-expansion-file