我有以下方法,只需从 URL 请求 .mp3 文件,加载 MediaPlayer 并根据 URL 是否加载来显示或隐藏播放按钮:
public class PlayMusicFragment extends Fragment {
private MediaPlayer mediaPlayer;
private void initializeMusicButton(String url) {
if (Objects.isNull(mediaPlayer)) {
mediaPlayer = GenericUtils.loadMediaPlayer(url, new MediaPlayer.OnPreparedListener() {
@Override
public void onPrepared(MediaPlayer mediaPlayer) {
binding.playMusicButton.setVisibility(VISIBILE);
}
}, new MediaPlayer.OnErrorListener() {
@Override
public boolean onError(MediaPlayer mediaPlayer, int i, int i1) {
binding.playMusicButton.setVisibility(GONE);
return false;
}
});
}
binding.playButton.setOnClickListener(view -> {
if (Objects.nonNull(mediaPlayer)) {
mediaPlayer.start();
}
});
}
}
在此片段中,我还重写了
onStop
方法以释放 MediaPlayer:
@Override
public void onStop() {
super.onStop();
if (Objects.nonNull(mediaPlayer)) {
if (mediaPlayer.isPlaying()) {
mediaPlayer.stop();
}
mediaPlayer.release();
mediaPlayer = null;
}
}
loadMediaPlayer
方法执行以下操作:
public static MediaPlayer loadMediaPlayer(String soundURL, MediaPlayer.OnPreparedListener onPreparedListener, MediaPlayer.OnErrorListener onErrorListener) {
MediaPlayer mediaPlayer = null;
try {
mediaPlayer = new MediaPlayer();
mediaPlayer.setAudioAttributes(new AudioAttributes.Builder()
.setContentType(AudioAttributes.CONTENT_TYPE_MUSIC)
.setUsage(AudioAttributes.USAGE_MEDIA)
.build());
mediaPlayer.setOnPreparedListener(onPreparedListener);
mediaPlayer.setOnErrorListener(onErrorListener);
mediaPlayer.setDataSource(soundURL);
mediaPlayer.setLooping(false);
mediaPlayer.prepareAsync();
} catch (Exception ex) {
if (Objects.nonNull(mediaPlayer)) {
mediaPlayer.release();
}
}
return mediaPlayer;
}
问题是 PlayStore Crashlytics 报告警告我,覆盖的
onStop
方法代码会生成 ANR:
我不明白为什么会发生这种情况,我用自己的手机和模拟器测试过,没有发现任何 ANR。
有什么提示吗?
不应将 null 分配给已释放的对象。把它留给垃圾收集器吧。