当您单击后退，应用程序不断在后台运行。 如果要停止音乐任何时候你走出了一定的活动覆盖的onStop或在onPause来停止你的声音。类似的东西

When you click back, the app keeps on running in the background. If you want to stop the music any time you get out of a certain activity override onStop or onPause to stop your sound. Something like that

@Override
protected void onStop(){
    super.onStop();
    //your code for stopping the sound
}