調用系統的媒體音量控制顯示

調大聲：

1 AudioManager audioMa=(AudioManager)this.getSystemService(Context.AUDIO_SERVICE);
2 audioMa.adjustStreamVolume(AudioManager.STREAM_MUSIC,AudioManager.ADJUST_RAISE,
AudioManager.FX_FOCUS_NAVIGATION_UP);

調小聲：

1 AudioManager audioMa=(AudioManager)this.getSystemService(Context.AUDIO_SERVICE);
2 audioMa.adjustStreamVolume(AudioManager.STREAM_MUSIC,AudioManager.ADJUST_LOWER,
AudioManager.FX_FOCUS_NAVIGATION_UP);