为什么mediaplayer.prepareAsync()抛出IllegalStateException?

时间:2019-07-13 18:18:54

标签: android android-mediaplayer alarm illegalstateexception

这是我的活动:

public class AlarmPlayerActivity extends AppCompatActivity implements MediaPlayer.OnPreparedListener {
    private MediaPlayer player;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_alarm_player);
        int alarm_number = getIntent().getIntExtra(Config.KEY_ALARM_NO, 0);
        ((TextView) findViewById(R.id.alarm_message)).setText(getString(R.string.alarms_was_set).concat(": " + alarm_number));
    }

    public void stopPlayingAlarm(View view) {
        if (player != null && player.isPlaying()) {
            player.reset();
            player.stop();
            player.release();
        }
    }

    @Override
    protected void onStart() {
        super.onStart();
        Uri uri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_ALARM);
        player = MediaPlayer.create(this, uri);
        player.setAudioStreamType(AudioManager.STREAM_ALARM);
        player.setLooping(true);
        player.setOnPreparedListener(this);
        player.prepareAsync();
    }

    @Override
    public void onPrepared(MediaPlayer mp) {
        mp.start();
    }
}

但是它会在IllegalStateException通话中抛出player.prepareAsync()

尽管我已经尝试过在此站点中找到其他答案,但我无法修复它。

请注意,此活动是从RTC_WAKEUP警报触发的广播接收器启动的。

这是我的AndroidManifest的一部分:

    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
    <uses-permission android:name="android.permission.EXPAND_STATUS_BAR" />
    <uses-permission android:name="com.android.alarm.permission.SET_ALARM" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" />
    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
    <uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS"/>

2 个答案:

答案 0 :(得分:2)

您好,回答晚了,但我认为您需要更多支持@Miller回答的解释。

您正在使用static MediaPlayer create (Context context, Uri uri)方法创建 MediaPlayer 实例。此方法将通过自己调用prepare()为您分配audioSessionId。

Note that since prepare() is called automatically in this method, you cannot change the audio session ID 

很显然,您不能编辑其audioSessionID。而当您致电player.prepareAsync();时,它会请求新的sessionId。结果为illegalStateExceptionsee docx

答案 1 :(得分:1)

MediaPlayer已在其中包含prepare()。因此,如果您调用第二个prepare(),它将抛出异常。

Link official doc