如何在Android onMediaButtonEvent中收听“ ACTION_DOWN”（按键）事件，以测量时间？

Question

我尝试获取时间System.currentTimeMillis()，而不是用户按下媒体按钮。但是，回调在媒体按钮再次上升时执行action == KeyEvent.ACTION_UP。

我不想在我的解决方案中使用BroadcastReceiver。

这是我的代码：

    MediaSession audioSession = new MediaSession(getApplicationContext(), "TAG");
    audioSession.setCallback(new MediaSession.Callback() {

        @Override
        html" target="_blank">public boolean onMediaButtonEvent(final Intent mediaButtonIntent) {
            String intentAction = mediaButtonIntent.getAction();

            if (Intent.ACTION_MEDIA_BUTTON.equals(intentAction))
            {
                KeyEvent event = (KeyEvent)mediaButtonIntent.getParcelableExtra(Intent.EXTRA_KEY_EVENT);
                if (event != null)
                {
                    int action = event.getAction();
                    if (action == KeyEvent.ACTION_DOWN) {
                        long stopTimeOfGame_millis = System.currentTimeMillis();
                        UtilsRG.info("time stopped: " +stopTimeOfGame_millis);

                    }
                    if (action == KeyEvent.ACTION_UP) {
                         long test = System.currentTimeMillis();
                         UtilsRG.info("time stopped up: " +test);

                    }
                }

            }
            return super.onMediaButtonEvent(mediaButtonIntent);
        }



    });

    PlaybackState state = new PlaybackState.Builder()
            .setActions(PlaybackState.ACTION_PLAY_PAUSE)
            .setState(PlaybackState.STATE_PLAYING, 0, 0, 0)
            .build();
    audioSession.setPlaybackState(state);

    audioSession.setFlags(MediaSession.FLAG_HANDLES_MEDIA_BUTTONS | MediaSession.FLAG_HANDLES_TRANSPORT_CONTROLS);

    audioSession.setActive(true);

日志输出：

时间停止下来：1473420286380
时间停止下来：1473420286383

我认为这些值之间的差异太小。

Answer 1

我自己解决了这个问题。诀窍是使用 event.getDownTime() 以下示例对其进行解释：

    audioSession = new MediaSession(getApplicationContext(), "TAG");
    audioSession.setCallback(new MediaSession.Callback() {

    @Override
    public boolean onMediaButtonEvent(final Intent mediaButtonIntent) {
        String intentAction = mediaButtonIntent.getAction();
        if (Intent.ACTION_MEDIA_BUTTON.equals(intentAction)) {
            KeyEvent event = mediaButtonIntent.getParcelableExtra(Intent.EXTRA_KEY_EVENT);

            if (event != null) {

                stopTimeOfGame_millis = event.getDownTime();
                double usersReactionTime = (event.getDownTime() - startTimeOfGame_millis) / 1000.0;
                UtilsRG.info("event.getDownTime(): " + usersReactionTime);


                double getEventTime = (event.getEventTime() - startTimeOfGame_millis) / 1000.0;
                UtilsRG.info("event.getEventTime(): " + getEventTime);

                int action = event.getAction();
                if (action == KeyEvent.ACTION_DOWN) {
                    long action_down = android.os.SystemClock.uptimeMillis();
                    double actionDown = (action_down - startTimeOfGame_millis) / 1000.0;
                    UtilsRG.info("ACTION_DOWN: " + actionDown);
                }

                if (action == KeyEvent.ACTION_UP) {
                    long action_up = android.os.SystemClock.uptimeMillis();
                    double actionUp = (action_up - startTimeOfGame_millis) / 1000.0;
                    UtilsRG.info("ACTION_UP: " + actionUp);
                }
            }
        }
        return true;
    }


    });

    PlaybackState state = new PlaybackState.Builder()
            .setActions(PlaybackState.ACTION_PLAY_PAUSE)
            .setState(PlaybackState.STATE_PLAYING, 0, 0, 0)
            .build();
    audioSession.setPlaybackState(state);

    audioSession.setFlags(MediaSession.FLAG_HANDLES_MEDIA_BUTTONS | MediaSession.FLAG_HANDLES_TRANSPORT_CONTROLS);

    audioSession.setActive(true);

我得到以下日志：

event.getDownTime（）：0.281

event.getEventTime（）：0.421

ACTION_DOWN：0.47

ACTION_UP：0.471

因此，现在我得到了用户按下按键的瞬间。

特别感谢Balkrishna Rawool