知道如果用的Soundpool声音的加载已经成功在Android 1.6 / 2.0 / 2.1 [英] Knowing if the loading of a sound with SoundPool has been successful on Android 1.6/2.0/2.1

问题描述

在Android 2.2+有叫什么<一href="http://developer.android.com/reference/android/media/SoundPool.OnLoadCompleteListener.html">SoundPool.OnLoadCompleteListener让知道一个声音是否已经被成功加载与否。

On Android 2.2+ there is something called SoundPool.OnLoadCompleteListener allowing to know whether a sound has been loaded successfully or not.

我针对低版本的API（最好是1.6，但可以去2.1），我需要知道是否声音已正确装入（因为它是由用户选择）。什么是正确的方式做到这一点？

I am targeting lower API version (ideally 1.6 but could go for 2.1) and I need to know whether a sound has been loaded correctly (as it is selected by the user). What's the proper way to do it?

我不希望用一次的MediaPlayer，如果正确使用的Soundpool加载声音？！

I hope not load the sound once with MediaPlayer and if correct with SoundPool?!

推荐答案

我实现了一种-兼容的 OnLoadCompleteListener 类的作品，至少为Android 2.1。

I implemented a kind-of-compatible OnLoadCompleteListener class that works at least for Android 2.1.

构造函数使用的Soundpool 对象，声音为其 SoundPool.load（..）已所谓的必须使用 OnLoadCompleteListener.addSound（soundId）注册。在此之后，听者周期性尝试播放所请求的声音（在零体积）。如果成功的话，它会调用您的实现的onLoadComplete ，像在Android 2.2+版本。

The constructor takes a SoundPool object, and sounds for which the SoundPool.load(..) has been called must be registered with OnLoadCompleteListener.addSound(soundId). After this, the listener periodically attempts to play the requested sounds (at zero volume). If successful, it calls your implementation of onLoadComplete, like in the Android 2.2+ version.

下面是一个使用示例：

    SoundPool mySoundPool = new SoundPool(4, AudioManager.STREAM_MUSIC, 0);
    OnLoadCompleteListener completionListener = new OnLoadCompleteListener(mySoundPool) {
        @Override
        public void onLoadComplete(SoundPool soundPool, int soundId, int status) {
            Log.i("OnLoadCompleteListener","Sound "+soundId+" loaded.");
        }
    }
    int soundId=mySoundPool.load(this, R.raw.funnyvoice,1);
    completionListener.addSound(soundId);  // tell the listener to test for this sound.

和这里的源：

abstract class OnLoadCompleteListener {    
    final int testPeriodMs = 100; // period between tests in ms

     /**
     * OnLoadCompleteListener fallback implementation for Android versions before 2.2. 
     * After using: int soundId=SoundPool.load(..), call OnLoadCompleteListener.listenFor(soundId)
     * to periodically test sound load completion. If a sound is playable, onLoadComplete is called.
     *
     * @param soundPool  The SoundPool in which you loaded the sounds. 
     */
    public OnLoadCompleteListener(SoundPool soundPool) {
        testSoundPool = soundPool;
    }

    /**
     * Method called when determined that a soundpool sound has been loaded. 
     *
     * @param soundPool  The soundpool that was given to the constructor of this OnLoadCompleteListener
     * @param soundId    The soundId of the sound that loaded
     * @param status     Status value for forward compatibility. Always 0.  
     */
    public abstract void onLoadComplete(SoundPool soundPool, int soundId, int status); // implement yourself

     /**
     * Method to add sounds for which a test is required. Assumes that SoundPool.load(soundId,...) has been called.
     *
     * @param soundPool  The SoundPool in which you loaded the sounds. 
     */
    public void addSound(int soundId) {
        boolean isFirstOne;
        synchronized (this) {
            mySoundIds.add(soundId);
            isFirstOne = (mySoundIds.size()==1);
        }
        if (isFirstOne) {
            // first sound, start timer
            testTimer = new Timer();
            TimerTask task = new TimerTask() { // import java.util.TimerTask for this
                @Override
                public void run() {
                    testCompletions();
                }  
            };
            testTimer.scheduleAtFixedRate(task , 0, testPeriodMs);
        }
    }

    private ArrayList<Integer> mySoundIds = new ArrayList<Integer>();
    private Timer testTimer;  // import java.util.Timer for this
    private SoundPool testSoundPool;

    private synchronized void testCompletions() {
        ArrayList<Integer> completedOnes = new ArrayList<Integer>();
        for (Integer soundId: mySoundIds) {
            int streamId = testSoundPool.play(soundId, 0, 0, 0, 0, 1.0f);
            if (streamId>0) {                   // successful
                testSoundPool.stop(streamId);
                onLoadComplete(testSoundPool, soundId, 0); 
                completedOnes.add(soundId);
            }
        }
        mySoundIds.removeAll(completedOnes);
        if (mySoundIds.size()==0) {
            testTimer.cancel();
            testTimer.purge();
        }
    }
}

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