Android：NotificationCompat.MediaStyle 操作按钮不执行任何操作

Question

我有一个简单的 Android 应用程序，其中包含一个Activity和一个Service源自MediaBrowserServiceCompat. 我已成功将其设置为通过使用MediaBrowserCompat和播放我的主要活动中的音频MediaControllerCompat。它甚至可以播放和暂停蓝牙耳机的音频。都好。

我的挑战涉及NotificationCompat.MediaStyle锁定屏幕和通知托盘中显示的通知。通知正确显示。但是，当我使用addAction()和添加按钮时MediaButtonReceiver.buildMediaButtonPendingIntent，它们不会执行任何操作。如果我添加一个虚拟的 PendingIntent 来启动我的主要活动，那就可以了。

这是我生成通知的代码（抱歉，这是在 Xamarin 中运行的 C#，因此大小写和名称将与您预期的略有不同）。这是我的服务级别内的。

var builder = new NotificationCompat.Builder(this, CHANNEL_ID)
    .SetVisibility(NotificationCompat.VisibilityPublic)
    .SetSmallIcon(Resource.Drawable.ic_launcher)
    .SetContentTitle("Title")
    .SetContentText("Content")
    .SetSubText("Subtext")
    .SetLargeIcon(icon)
    .SetColor(Android.Graphics.Color.DarkOrange)

    .SetContentIntent(intent)
    .SetDeleteIntent(MediaButtonReceiver.BuildMediaButtonPendingIntent(this, PlaybackStateCompat.ActionStop))

    .AddAction(new NotificationCompat.Action(
        Resource.Drawable.ic_pause, "Pause",
        MediaButtonReceiver.BuildMediaButtonPendingIntent(this, PlaybackStateCompat.ActionPause)))

    .SetStyle(new Android.Support.V4.Media.App.NotificationCompat.MediaStyle()
        .SetShowActionsInCompactView(0)
        .SetMediaSession(this.mediaSession.SessionToken)
        .SetShowCancelButton(true)
        .SetCancelButtonIntent(MediaButtonReceiver.BuildMediaButtonPendingIntent(this, PlaybackStateCompat.ActionStop))
    );

this.StartForeground(NOTIFICATION_ID, builder.Build());

到目前为止，我已经看到了以下内容来尝试解决此问题：

• 当我开始播放时，我使用MediaSession.setActive(true)
• 每次我开始和停止播放时，我都会在PlaybackStateCompat
• 我已正确设置会话令牌。
• 我的清单中没有设置任何内容，也没有设置任何内容来处理，因为我的目标是 Android 5.0 及更高版本并使用这些类，我的理解是，这不再是必要的。MediaButtonReceiverandroid.intent.action.MEDIA_BUTTON*Compat

我知道媒体按钮事件已正确路由到我的应用程序，因为我的蓝牙耳机按钮可以工作。我在我的车上尝试过，它也在那里工作。只是通知中的按钮不起作用。我期望他们生成对MediaSessionCompat.Callback. 这是不正确的吗？我在这里做错了什么？

如果有任何指点，我将不胜感激。

---

更新： 我成功了。<application>我需要在清单节点内添加以下内容：

<receiver android:name="android.support.v4.media.session.MediaButtonReceiver">
    <intent-filter>
        <action android:name="android.intent.action.MEDIA_BUTTON" />
    </intent-filter>
</receiver>

...以及实现的服务节点内的以下内容MediaBrowserServiceCompat：

<intent-filter>
    <action android:name="android.media.browse.MediaBrowserService"/>
</intent-filter>

我仍然有点困惑为什么这是必要的，因为我的蓝牙耳机和汽车信息娱乐系统的按钮按下都很好地路由到了应用程序。更重要的是，谷歌表示：

如果您的应用程序中已经有MediaBrowserServiceCompat， 则默认情况MediaButtonReceiver下会将收到的按键事件传递给 MediaBrowserServiceCompat。您可以在您的 MediaSessionCompat.Callback.

他们将此作为选项“服务处理 ACTION_MEDIA_BUTTON”的替代方案，因此我认为这意味着我不需要对清单执行任何操作。如果有人能在这里启发我，我将不胜感激。

但是，就其价值而言，这对我有用。

Answer 1

可能您还没有设置操作。看下面的代码，它展示了如何用意图绑定按钮。请针对需要通道的 android O 设备进行修改。

import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.support.v4.media.MediaDescriptionCompat;
import android.support.v4.media.MediaMetadataCompat;
import android.support.v4.media.session.MediaSessionCompat;
import android.support.v4.media.session.PlaybackStateCompat;
import android.support.v7.app.NotificationCompat;

/**
 * Keeps track of a notification and updates it automatically for a given MediaSession. This is
 * required so that the music service don't get killed during playback.
 */
public class MediaNotificationManager extends BroadcastReceiver {
    private static final int NOTIFICATION_ID = 412;
    private static final int REQUEST_CODE = 100;

    private static final String ACTION_PAUSE = "com.example.android.musicplayercodelab.pause";
    private static final String ACTION_PLAY = "com.example.android.musicplayercodelab.play";
    private static final String ACTION_NEXT = "com.example.android.musicplayercodelab.next";
    private static final String ACTION_PREV = "com.example.android.musicplayercodelab.prev";

    private final MusicService mService;

    private final NotificationManager mNotificationManager;

    private final NotificationCompat.Action mPlayAction;
    private final NotificationCompat.Action mPauseAction;
    private final NotificationCompat.Action mNextAction;
    private final NotificationCompat.Action mPrevAction;

    private boolean mStarted;

    public MediaNotificationManager(MusicService service) {
        mService = service;

        String pkg = mService.getPackageName();
        PendingIntent playIntent =
                PendingIntent.getBroadcast(
                        mService,
                        REQUEST_CODE,
                        new Intent(ACTION_PLAY).setPackage(pkg),
                        PendingIntent.FLAG_CANCEL_CURRENT);
        PendingIntent pauseIntent =
                PendingIntent.getBroadcast(
                        mService,
                        REQUEST_CODE,
                        new Intent(ACTION_PAUSE).setPackage(pkg),
                        PendingIntent.FLAG_CANCEL_CURRENT);
        PendingIntent nextIntent =
                PendingIntent.getBroadcast(
                        mService,
                        REQUEST_CODE,
                        new Intent(ACTION_NEXT).setPackage(pkg),
                        PendingIntent.FLAG_CANCEL_CURRENT);
        PendingIntent prevIntent =
                PendingIntent.getBroadcast(
                        mService,
                        REQUEST_CODE,
                        new Intent(ACTION_PREV).setPackage(pkg),
                        PendingIntent.FLAG_CANCEL_CURRENT);

        mPlayAction =
                new NotificationCompat.Action(
                        R.drawable.ic_play_arrow_white_24dp,
                        mService.getString(R.string.label_play),
                        playIntent);
        mPauseAction =
                new NotificationCompat.Action(
                        R.drawable.ic_pause_white_24dp,
                        mService.getString(R.string.label_pause),
                        pauseIntent);
        mNextAction =
                new NotificationCompat.Action(
                        R.drawable.ic_skip_next_white_24dp,
                        mService.getString(R.string.label_next),
                        nextIntent);
        mPrevAction =
                new NotificationCompat.Action(
                        R.drawable.ic_skip_previous_white_24dp,
                        mService.getString(R.string.label_previous),
                        prevIntent);

        IntentFilter filter = new IntentFilter();
        filter.addAction(ACTION_NEXT);
        filter.addAction(ACTION_PAUSE);
        filter.addAction(ACTION_PLAY);
        filter.addAction(ACTION_PREV);

        mService.registerReceiver(this, filter);

        mNotificationManager =
                (NotificationManager) mService.getSystemService(Context.NOTIFICATION_SERVICE);

        // Cancel all notifications to handle the case where the Service was killed and
        // restarted by the system.
        mNotificationManager.cancelAll();
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        final String action = intent.getAction();
        switch (action) {
            case ACTION_PAUSE:
                mService.mCallback.onPause();
                break;
            case ACTION_PLAY:
                mService.mCallback.onPlay();
                break;
            case ACTION_NEXT:
                mService.mCallback.onSkipToNext();
                break;
            case ACTION_PREV:
                mService.mCallback.onSkipToPrevious();
                break;
        }
    }

    public void update(
            MediaMetadataCompat metadata,
            PlaybackStateCompat state,
            MediaSessionCompat.Token token) {
        if (state == null
                || state.getState() == PlaybackStateCompat.STATE_STOPPED
                || state.getState() == PlaybackStateCompat.STATE_NONE) {
            mService.stopForeground(true);
            try {
                mService.unregisterReceiver(this);
            } catch (IllegalArgumentException ex) {
                // ignore receiver not registered
            }
            mService.stopSelf();
            return;
        }
        if (metadata == null) {
            return;
        }
        boolean isPlaying = state.getState() == PlaybackStateCompat.STATE_PLAYING;
        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(mService);
        MediaDescriptionCompat description = metadata.getDescription();

        notificationBuilder
                .setStyle(
                        new NotificationCompat.MediaStyle()
                                .setMediaSession(token)
                                .setShowActionsInCompactView(0, 1, 2))
                .setColor(
                        mService.getApplication().getResources().getColor(R.color.notification_bg))
                .setSmallIcon(R.drawable.ic_notification)
                .setVisibility(Notification.VISIBILITY_PUBLIC)
                .setContentIntent(createContentIntent())
                .setContentTitle(description.getTitle())
                .setContentText(description.getSubtitle())
                .setLargeIcon(MusicLibrary.getAlbumBitmap(mService, description.getMediaId()))
                .setOngoing(isPlaying)
                .setWhen(isPlaying ? System.currentTimeMillis() - state.getPosition() : 0)
                .setShowWhen(isPlaying)
                .setUsesChronometer(isPlaying);

        // If skip to next action is enabled
        if ((state.getActions() & PlaybackStateCompat.ACTION_SKIP_TO_PREVIOUS) != 0) {
            notificationBuilder.addAction(mPrevAction);
        }

        notificationBuilder.addAction(isPlaying ? mPauseAction : mPlayAction);

        // If skip to prev action is enabled
        if ((state.getActions() & PlaybackStateCompat.ACTION_SKIP_TO_NEXT) != 0) {
            notificationBuilder.addAction(mNextAction);
        }

        Notification notification = notificationBuilder.build();

        if (isPlaying && !mStarted) {
            mService.startService(new Intent(mService.getApplicationContext(), MusicService.class));
            mService.startForeground(NOTIFICATION_ID, notification);
            mStarted = true;
        } else {
            if (!isPlaying) {
                mService.stopForeground(false);
                mStarted = false;
            }
            mNotificationManager.notify(NOTIFICATION_ID, notification);
        }
    }

    private PendingIntent createContentIntent() {
        Intent openUI = new Intent(mService, MusicPlayerActivity.class);
        openUI.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
        return PendingIntent.getActivity(
                mService, REQUEST_CODE, openUI, PendingIntent.FLAG_CANCEL_CURRENT);
    }
}