Android 4.4 - 播放默认音乐播放器

Question

谁能告诉我为什么这不再适用于 Kitkat 以及如何解决它？

    private Intent player;
    player = new Intent(Intent.ACTION_MEDIA_BUTTON);
    synchronized (this) {
        player.putExtra(Intent.EXTRA_KEY_EVENT, new KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_MEDIA_PLAY));
        sendOrderedBroadcast(player, null);

        player.putExtra(Intent.EXTRA_KEY_EVENT, new KeyEvent(KeyEvent.ACTION_UP, KeyEvent.KEYCODE_MEDIA_PLAY));
        sendOrderedBroadcast(player, null);
    }

Answer 1

API 级别 19 中有专门为此目的创建的新方法 AudioManager.dispatchMediaKeyEvent(KeyEvent)。

http://developer.android.com/reference/android/media/AudioManager.html#dispatchMediaKeyEvent(android.view.KeyEvent)

此代码适用于 KitKat：

AudioManager am = (AudioManager)context.getSystemService(Context.AUDIO_SERVICE);

long eventtime = SystemClock.uptimeMillis() - 1;
KeyEvent downEvent = new KeyEvent(eventtime, eventtime, KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE, 0);
am.dispatchMediaKeyEvent(downEvent);

eventtime++;
KeyEvent upEvent = new KeyEvent(eventtime,eventtime,KeyEvent.ACTION_UP,KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE, 0);         
am.dispatchMediaKeyEvent(upEvent);

Answer 2

我不知道你为什么认为代码首先是可靠的。不要求任何应用程序对这些特定的广播进行任何响应。

除此之外，Android 还在继续打击发送此类虚假系统广播的应用，例如 Android 4.4 blocking apps sending ACTION_MEDIA_MOUNTED broadcasts。我会检查 LogCat，看看你是否有任何关于你滥用此广播的警告或任何内容。