Android SoundPool循环播放

SoundPool适用于同时播放多个短促的音乐，如游戏的音效，支持单次播放、多次播放和无限循环播放

源码

以下源码的注释对loop参数说得很明白，总结如下：

• 0表示不循环
• -1表示无限循环（注意该情况需主动调用stop()方法停止播放）
• 大于0的值具体表示重复播放的次数，总的播放次数=loop+1（第一次播放加上重复播放的次数）

SondPool源码开头中loop的相关说明

 * <p>Sounds can be looped by setting a non-zero loop value. A value of -1
 * causes the sound to loop forever. In this case, the application must 
 * explicitly call the stop() function to stop the sound. Any other non-zero
 * value will cause the sound to repeat the specified number of times, e.g.
 * a value of 3 causes the sound to play a total of 4 times.</p>

 play()方法的源码，其中包含对loop参数的说明

/**
 * Play a sound from a sound ID.
 *
 * Play the sound specified by the soundID. This is the value 
 * returned by the load() function. Returns a non-zero streamID
 * if successful, zero if it fails. The streamID can be used to
 * further control playback. Note that calling play() may cause
 * another sound to stop playing if the maximum number of active
 * streams is exceeded. A loop value of -1 means loop forever,
 * a value of 0 means don't loop, other values indicate the
 * number of repeats, e.g. a value of 1 plays the audio twice.
 * The playback rate allows the application to vary the playback
 * rate (pitch) of the sound. A value of 1.0 means play back at
 * the original frequency. A value of 2.0 means play back twice
 * as fast, and a value of 0.5 means playback at half speed.
 *
 * @param soundID a soundID returned by the load() function
 * @param leftVolume left volume value (range = 0.0 to 1.0)
 * @param rightVolume right volume value (range = 0.0 to 1.0)
 * @param priority stream priority (0 = lowest priority)
 * @param loop loop mode (0 = no loop, -1 = loop forever)
 * @param rate playback rate (1.0 = normal playback, range 0.5 to 2.0)
 * @return non-zero streamID if successful, zero if failed
 */
public final int play(int soundID, float leftVolume, float rightVolume,
                      int priority, int loop, float rate) {
    baseStart();
    return _play(soundID, leftVolume, rightVolume, priority, loop, rate);
}

单次播放

soudPool.play(soundID, leftVolume, rightVolume, priority, 0, rate);

多次播放

// 重复播放1次，也就是总共播放2次
soudPool.play(soundID, leftVolume, rightVolume, priority, 1, rate);
// 重复播放2次，也就是总共播放3次
soudPool.play(soundID, leftVolume, rightVolume, priority, 2, rate);
// 重复播放3次，也就是总共播放4次
soudPool.play(soundID, leftVolume, rightVolume, priority, 3, rate);

循环播放

soudPool.play(soundID, leftVolume, rightVolume, priority, -1, rate);